# HOW TO CHANGE A THERMOSTAT ON A 225TT



## John-H

*HOW TO CHANGE A THERMOSTAT ON A 225TT*

If you are suffering from a low temperature reading, having to wait ages for some warm air, or suffering excess fuel consumption, you may need your thermostat changing - espescially if your TT is an older model. Worn thermostats can stick partly open, behave sluggishly and not regulate the temperature properly, causing your ECU to run a rich mixture. Here's a graph of my engine temperature on the way to work:










You can see the poor regulation with readings as low as 77° C. on over-run, to 100° C. stuck in traffic. Other people have reported running 75° C. and suffering a rich mixture and low mpg. I think mine was verging to that condition.

*Diagnosis:*

Do the 49C trick to confirm the real live reading of the engine temperature via the climate control:

* Press re-circulating air and then de-mist up arrow simultaneously.
* Turn temperature control knob until 49C is displayed.
* Press re-circulating air to display reading.
* Press re-circulating air and up arrow again to cancel.

Your needle dash gauge shows a software weighted figure that sits at a re-assuring 90° C. normally and only departs when the 49C figure is significantly different (>10° C.).

If the two readings (dashpod temperature needle, and 49C) agree, then it rules out the possibility that your dashpod is at fault which can happen! Bear in mind the software weighting. Here are some examples:

.... 49C = 82° C. then the dashpod should read 90° C. (weighted to appear running normal 90° C.)
.... 49C = 105° C. then the dashpod should read 105° C. (should tell raw truth)
.... 49C = 90° C. and the dashpod = 100° C. then you have a faulty dashpod
.... 49C = 93° C. and the dashpod = 80° C then you have a faulty dashpod
.... 49C = 75° C. then the dashpod should read 75° C. (should tell raw truth) ... but ...
.... 49C = 75° C. and the dashpod = 75° C. then you have either a faulty sensor or thermostat (should run 90° C).

If your temperature is low, e.g. 75° C. then this generally indicates you need a new thermostat and it's sticking open. You can often see the temperature fall on a long overrun when no petrol is being burnt but the radiator is still cooling the engine. BUT check the water temperature with a thermometer to confirm the water temperature is real and not a faulty sensor!

If 49C is fine, a high or low needle reading is going to be caused by a faulty dashpod.

If 49C shows too hot as well as the needle gauge it's more likely to be a stuck thermostat or failed waterpump, collapsed hose, non functioning fan etc.

Bear in mind that when stuck in traffic and with no airflow the engine temperature will normally climb until the radiator fans both cut in at ~96°C and ~100° C. on their own two stage thermostatic switch and bring the temperature down with a low and high speed response. The temperature will cycle up and down like this with the fans turning on and off, unless alternative airflow is resumed by the car moving, or, if you have the air conditioning turned on, which creates airflow by continuous use of the low speed fan response _if_ cooling the cabin. Both fans are electrically connected in parallel so should both respond together. They each have an internal resistor for low speed running but these resistors can sometimes fail leaving only the ~100°C operation on one or both fans and air conditioning that performs poorly when the vehicle is stationary.

Another thing to bear in mind is that there are two temperature sensors in the same screw in sensor unit on the engine. One sensor (G2) feeds the needle gauge and one (G62) feeds the ECU. G2 is also read by the climate control as 49C. There has been some confusion and misinformation about this: 49C does NOT read the ECU sensor and 51C does NOT represent the equivalent of the dashpod software weighted 49C reading. Ignore 51C.

*Presuming you need to change the thermostat:*
(Click to enlarge pictures)

These are the parts you'll need:

Some *G12+ Audi Antifreeze* sold in 1.5L containers. You don't need to replace all the coolant but you may spill some. Total coolant capacity varies but is in the order of 5L (40% mix). It's clear pink/purple in colour. If your current antifreeze is dirty brown you've got a mixture of G11 and G12 and should get the system flushed and replaced with G12+ immediately before you get engine damage. It is unlikely for there to be a mix however.










*Thermostat P/No: 050 121 113 C @ £12.41 + VAT from Audi (87C - 102 C)
(Note BAM varient may be P/N: 050121 113 B (Marked Yellow) 80C - 102 C)
Sealing ring: P/No: 038 121 119 B @ £1.49 + VAT from Audi*










*N.B You may want to get a spare dipstick tube. They are quite cheap from Audi and can become brittle with age and have a habit of breaking during this job unless you are careful.*

*Procedure:*

You need to drain the system, so, first get the car up on ramps. The standard ramps don't work too well with modern spoilers. A piece of wooden joist on each ramp, with a couple of bent nails to act as hooks onto one of the ramp rungs, give enough initial lift to ensure the spoiler easily clears the ramps. Still not painted  .










Next job is to remove the cover from under the engine. There are quite a few Torx screws to remove. Don't forget these screws that join the cover to the wheel arch liner! Then the cover will pull towards the rear, disengaging the locating tabs at the front of the cover and fall away.

















Next, take off the cover in front of the inlet manifold. The screws turn through 90 degrees to disengage (some later TTs have Posidrive screws which can be seized tight - make sure your screwdriver is a good fit!). Prise off the hose clip at the end and undo the two socket screws with a 5mm Allen key. Then tuck to one side without disconnecting the pipes and wiring.
























Be very careful not to break the dipstick tube as they get brittle with age so it might be advisable to get a spare as they are cheap. The metal plate has a tang at the back which engages in the dipstick - be careful to pull the plate up but keep it back in contact with the inlet manifold as you raise it, otherwise if you pull it forward before the tang is disengaged the tube will likely snap. If you replace it, try to pull it out straight. If pieces break off and get stuck inside the metal tube to the sump, insert a small bolt, head first, to go past the pieces without touching and then drag them out.

















You can now catch a glimpse of the thermostat housing behind the alternator. Don't undo it yet until you've drained the system. There's a tap at the nearside bottom corner of the radiator. *The tap turns anticlockwise 1/4 turn and then pulls out a 1/2 inch to release.* Drain into at least a 5Litre (clean!!!) container - it's a slow trickle.
























Now, the design of the cooling system is a little odd I think. The pipe from the thermostat goes down to the bottom of the radiator by the tap. Most cars feed the top of the radiator. Consequently on the TT, the tap does not drain the full system as it can't fully drain the cylinder block. To complete the task you need to loosen off this hose on the oil cooler. If you don't do this, pulling out the thermostat will spill about 1Litre of coolant over the floor! As I found out  .










So, now compress the hose clip with some pliars - I used a small Mole wrench and pull the clip back over the hose. Then twist and manipulate until it comes off. Pull the small connector off the alternator for better access. The top bolt can easily be removed with a 1/4" drive universal joint and extensions. It's a 10mm A/F head. The bolts also have a 5mm Allen key socket, so you have options. You can twiddle the last few turns with your fingers - seen through the inlet manifold.































The bottom bolt, however, is more difficult. I fould a ring spanner and a 1/4" drive socket and ratchet was useful here. Wak told me later that removing the main alternator connector and taping it to one side helps but I managed without trying this. Access is difficult and you can hardly see what you are doing with your hands in the way. Finally it's off and you can prize out the O ring around the thermostat and remove it.






































Next, presuming you don't have to spend half an hour mopping up, scrape any rust or gunk from the flange face and clean away any debris. The thermostat doesn't seal on this face so you just need it flat. Now lubricate the new O ring with antifreeze and insert the thermostat, spring first, into its recess. Insert the O ring around it, which stops it falling out. Make sure you've got the thermostat's metal bridge (where the actuator bar presses) vertical by rotating the thermostat. Also lubricate the housing elbow face before assembly. The manual says to tighten the bolts to 15 Nm (11 ft/Lb).






































Now replace the hose and hose clip and make sure the small tube is in front of the dip stick before swinging the solenoid valve mounting plate back into place, engaging in the dipstick guide tube, and tightening the bolts to 10 Nm. Re-attach the hose clip and replace the cover. I took the opportunity to remove some rust off this plate and paint with black Hammerite before putting the cover back on.
























Now, ensuring your drain tap is closed, replace the coolant. I'd taken my covers off to retreive a dropped bolt, but it helps to top up and see what you're doing and achieve an arty lighting shot to see the level :wink: :































*Recommended protection coolant mixture ratios are:

-25° C. = 40% Antifreeze 60% water 
-35° C. = 50% Antifreeze 50% water*

Use distilled water to mix and avoid problems. Keep between these ratios. Too little antifreeze may freeze obviously but too much won't cool as well.

Top up to the full mark and run the engine with the filler cap off. You will probably find the level drops so top it up. As the engine warms up it may drop further. It's best to achieve full working temperature and check for leaks under pressure, so when youre satisfied the level has stopped dropping and the engine has warmed up (thermostat open, coolant circulating), cap it off and get it up to full temperature at a fast idle. You can squeeze the hoses to tell if there's pressure. Don't forget to put the engine undershield back on when you're happy.

Keep some coolant with you on you first run. You may need to top up again. I needed almost 1/2 a litre.

*Results:*

As you can see, the temperature is now much more stable and the average temperature now sits at 94° C. Well away from the point where the mixture richens and your mpg suffers.


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## Wak

Nice write up,

only thing I'd add is on the first run up, ensure the cap is off it helps get rid of air locks, let the car idle up to 5-10 minutes and keep an eye on the level.

Then cap it off and runit it a bit more, check for leaks before you go on your test run.


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## KenTT

Another really nice write up from you John, well done.

Just a thought.

:idea: With the MKI TT getting older and the likely increase in DIY jobs taking place, these write up's would make a good reference section in AbsoluTTe, plus you would be able to look at them while doing the job at hand. Thats if all parties agreed to it of course.


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## John-H

Thanks for the comments Wak and Ken. You describe exactly what I did Wak. I've edited it a little to improve that last section.

Ken, you make a good point about TTs getting older etc. I've no objection to my stuff being used - it's to help anyone doing it and provide a record. There have been quite a few excellent "how to" posts people have done which could be included. Jay has added some to the FAQ section and of course Wak's got loads of stuff on his site. It would be useful to have practical stuff in a magazine. I miss magazines like CCC and Popular Motoring. Paper is quite a good medium for long term storage. Web hosts of photographs may not be and it's a bit of a risk that they may go out of business :? .


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## JayGemson

My TT recently developed a thermostat fault at 68,000miles. The coolant temperature would drop significantly whenever I coasted for a short while, especially down hill.

I followed John's guide, cross referencing this one from the AudiWorld forum in the states (http://forums.audiworld.com/tt/msgs/1304805.phtml) and managed to complete the job in less than two hours in total. I chose not to drain the coolant system, therefore alleviating the need to jack up the car and remove the undertray. I lost less than 2L of coolant when I removed the thermostat hose which dropped down the block to the floor.

One thing I would say here though is the most difficult part of the job is space, it's a very confined area. Having the right tools is an absolute must, small hands would also come in very handy :wink:


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## John-H

Thanks for the feedback Jay  .

I read through the AudiWorld forum How To. There are some good pictures there. I'm not sure about removing the dipstick tube - espescially if it's likely to break. I found I didn't need to remove it. Also the universal joint used on the bottom bolt is through a tight angle - you'll need a good universal joint for that to work.

Interesting that you managed to get away without draining the system. I think I'll add a note to the How To to say that that's a possibility. It certainly makes the job easier. I've got away doing that on other engines but I wasn't confident that would work on the TT as it's low down on the block and the Bentley manual says to drain it. Swapping the thermostat over to plug the hole quick is a must, as is keeping the cap on to stop air going in and water coming out. It's not good for paint finishes to have antifreeze slopping around on the undertray but it is dilute and you could dilute it away completely with more water.


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## gt russell

fantastic and well detailed John, I will be doing mine soon, its good reading how other people learn from mistakes ie the hose on the oil cooler, thats one ill remember. Cheers John :wink:


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## JayGemson

You're welcome John  Your comments are all accurate in response.

My universal joint wouldn't operate perfectly on the bottom bolt either, but it was enough to un-bind it such that I could then loosen and remove it by hand.

Also, I found it wasn't really feasible to swap in the new thermostat without getting flustered and losing a lot of coolant anyway so I let it drain to that level, then I could take my time and ensure the mating surfaces were free from gunk.


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## jono-williams

Another useful "How To" Thanks John-H

Here's a couple of tips following my experience, I must say it wasn't a pleasant one, very fiddley and awkward just for a couple of screws and expect a few cuts and bruises on your hands. It was worth it as I now have a constant temperature. The stores guy at Audi Harrogate was trying to tell me that these hardly fail and was trying to talk me out of it and say it was a sensor....he was wrong!!!

1. A useful item to have in a mini maglite, you can then see the bottom screw a lot better and it wedges just between the inlet manifold and the plastic engine cover so you can be hands-free. You can also hold onto it but its a bit tricky when trying to get the socket on.

2. I removed the alternator connection...just remember to dis-connect the battery!!! I didn't and had a few sparks. It would be better to have removed the cable clamp to give you better access but just removing the connection and pushing the cable down a little certainly helped.

Hope this helps you DIYers out there....


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## droopsnoot

jono-williams said:


> The stores guy at Audi Harrogate was trying to tell me that these hardly fail and was trying to talk me out of it and say it was a sensor....he was wrong!!!


Interesting - mine does the same thing, sits at a quarter on the gauge, and I've been told the same thing during it's services at the main dealer.

As it's not causing any long-term damage, I think I'll leave it until the better weather comes back. My MPG is reasonable at the moment (~31mpg on average) so hopefully this might make it even better. Thanks for the great write-up though, really useful.


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## Marcr

Hi there - very interesting.. my temp keeps dropping from 90 to 50 even when the engine is really hot. the test I have done that you mentioned shows the same dropping in the dash-pod as well as the same dropping in the display... would this mean that my sensor/thermostat is faulty? please advise...


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## John-H

Marcr said:


> Hi there - very interesting.. my temp keeps dropping from 90 to 50 even when the engine is really hot. the test I have done that you mentioned shows the same dropping in the dash-pod as well as the same dropping in the display... would this mean that my sensor/thermostat is faulty? please advise...


Could be. The only way to really tell is to meaure the coolant temperature with a thermometer and see if it matches or measure the sensor resistance at a known temperature. The sensor is not too dificult to change at least.


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## Marcr

I have been told the sensor needs replacing.... hmmmm Thanks !!


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## Daz8n

Do you definitely need ramps to drain the system?? I don't have any!! Or a jack.. or axle stands!!  lol


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## jjones

did mine on jacks/stands no problem (would investigate the not draining method though as that pipe is a f%$^^$%$)


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## Daz8n

jjones said:


> did mine on jacks/stands no problem (would investigate the not draining method though as that pipe is a f%$^^$%$)


I meant I don't have ramps... OR jacks... OR axle stands!!!! lol


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## stevebeechTA

Excellent read, Thank you. A job i need to do, i have the parts and the correct fluid, just need to get some water. does the alternator have to be moved

thanks steve


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## Thundercat

Don't think it needs to be moved. Read a couple of "how to's" an didn't mention it 8)


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## John-H

It's awkwardly in the way but you can work round it with difficulty. It helps to have a good few tools.


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## markypoo

I need to get round to doing mine, did I read somewhere there are 2 different thermostats with different temperature ratings ????


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## John-H

There's only one listed in my Etka: P/N: 050 121 113 - coolant thermostat 87C-102C AJQ,APX,APP,AUQ,ARY,BAM,AUM


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## markypoo

Ah ok and good to have the part No to as my local dealers are useless without them, last time I had to go into the parts office and point out on the screen the parts I needed :roll:


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## Daz8n

Just went out to do this and couldn't get the screws off for the inlet manifold cover!! They are shafted!!!!! Any suggestions? Might have to bring my drill home from work and drill them out next weekend!! Could do the Wakbox then too!!! lol

Daz


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## John-H

Do you mean the vertical 90 degree twist and release screws holding the decorative cover on, or the horizontal socket head screws holding in place the base plate bracket?


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## Daz8n

^^^^ These ones but they weren't the 90deg twist ones, they had proper philips heads... tight as ****!!!


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## ViperOneZero

just to advise everybody, do not buy cheap thermos..i did and am having to replace it after 6 months use... as its not opening properly leading to high engine temps.


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## John-H

Daz8n said:


> ^^^^ These ones but they weren't the 90deg twist ones, they had proper philips heads... tight as ****!!!


I recognise that screwdriver! 

That's odd. The normal ones slot into weak spring clips. I would have thought a few taps downwards would loosen any rust and allow them to twist. I wonder if someone has used the threaded ones, jammed them in or added captive nuts (or self tappers - shudder!) and they've rusted up?


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## Daz8n

Yeah I think someone has used threaded ones!! :x I might try an impact driver and if no good will have to drill them out!!


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## Thundercat

Well, I joined the thermostat club today and I never want to do another one again! That bottom bolt is a total nightmare :? Anyway, got there in the end and the needle now sits nicely at 90c 8)


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## Daz8n

Should I be seeing around 90 degC after about 10mins sat running with the cap off or once I get out on the road???

Daz


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## John-H

Daz8n said:


> Should I be seeing around 90 degC after about 10mins sat running with the cap off or once I get out on the road???
> 
> Daz


Hi Daz,

In this cold weather it may take a good while to get to 90 deg C. at idle. Keeping the engine at about 2,000 rpm will speed up the process but as soon as the thermostat starts to open watch you don''t cause the coolant to well up and over the expansion tank, so shut off the revs to idle when the needle gets to 90 deg C. and keep watching the expansion tank. Make the first drive a short one and top up.

By the way, I found out that later TTs had different screws holding the trim cover over the plate by the dipstick. Early ones like mine had the 90 deg twist to undo spring clip type and later ones used the same design as for the battery and expansion tank cover Posidrive screws. Make sure your screwdriver is a good fit (i.e. not similar but different Phillips but correct size Pozidrive) if the screws are tight.

Cheers,
John


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## Daz8n

I ended up having to drill the screws out!! They were solid!!!

I got to 93 degC after running for a bit but if you read HERE you'll find I wasn't happy for long!!

Cheers


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## Thundercat

Mine took ages to get to 90 as well but it was cold when I changed the thermostat. Also checked mine with the climate control code to confirm but got there in the end. 8)


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## physiojlb

On my way to doing this atm. so far i've taken all the stuff off and drained the coolant, it was brown so chucked it away.

Instead of pulling off countless hoses I just ran about 10litres of water through the system and i'll let the rest come out when I pull the thermostat out tomo as its getting dark should just be water or 99.99% diluted so shouldnt cause anyharm anywhere.

One prob, I think i'm missing the undertray cover bit from the bay.. as i just put my hand in and can get to the tap for the coolant and everything else. Which worries me a bit as anyone could jus walk past and turn the tap on my coolant! Anyone know how much from audi?

cheers


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## physiojlb

done this now, just getting the coolant level right now. If you use the right tools this would only take an hour max. For the lower bolt you need the smallest possible universal joint and extension bars etc and its fine, when refitting it I put the bolt in the housing and then located it and tightened the top 1/4 of the way then got the lower started and it worked fine. I tied a piece of string around the nut to make sure i didnt loose it, tied the other end to the plate that you remove to gain access.

Took it for a quick spin, went up to 90 pretty quick and then got a beep about coolant level so topped it up and its fine. Gonna keep a bottle of dilute in the car for the next couple of drives just incase.


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## John-H

Sounds good


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## Daz8n

Definitely the smallest UV you can find!! lol

I've not got dilute in the car but got a bottle of G12, a bottle of distilled water and a measuring jug in the boot. :lol: Taking the car on its first long run today since doing it!! Hope its ok!!  

Daz


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## droopsnoot

physiojlb said:


> If you use the right tools this would only take an hour max.


You must have very flexible arms. I consider myself reasonably dexterous but it took me ages to get the bottom cover bolt back in. Then I dropped the UJ and socket down into the engine bay, but was chuffed to find they'd dropped right through onto the cover and slid to the back. All OK afterwards though.


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## physiojlb

I'm 6foot 6 lol. And my arms are pretty big. I found if u hold the bottom bolt in the housing and then put the housing in, then Tighten the top one it's easy. The piece of string ment I could jus leave the bolt in and not worry about it dropping.


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## stevebeechTA

Just been out to do mine, striped it all out but i just have not got the correct gear or the confidance to do it plus i did not have much light left :x It is bloody tight down there though. I will get it done on wednesday at bigbyson's as he will give me the dutch courage to do it. He knows his way round the tt like the back of his had. I will let you all know on Wednesday night how i go on.

cheers steve


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## ross5675cn5a

I am happy man thanks to John H guide to testing and changing the thermostat  I have just changed mine and now it works fine. I have a 2001 180 TT and since I bought the car it always ran at 70c and never seemed to hit 90c - which I now know it should have. I was told they run cool and air con fans help - wrong advice I thing! Read the forum advice and completed the check mentioned on John H guide - so not the gauge. A trip to parts dealer (not audi) and picked up a thermostat and o ring for £7.00 and a few extension for the 3/8 ratchet and anti freeze and I was off. I followed the guide and another I read on the site and took all the *easy* options. I did not remove the under guard or the dip stick or drain the system. I only lost about 1 1/2 litre of coolant disconnecting the hose from the thermostat housing and only a small amount when I swapped the old thermostat for the new one. I used by daughters old sand pit top to catch the antifreeze under the car and a quick wash down should have got rid of any excess. You really do need a long ratchet extension, patients and blue tack to fix the bottom screw back to the housing at the end.

So far so good. The car now reaches 90c and when hot the fan kicks in about 100 and then drops back in good time. I must say it ran like a proper sports car when I took it for a run and had a kick about it. But, I have now discovered that the one of the black plug covers over the spark plugs is lifting................so guess what I am about to look at next!

Thanks for all the info - you guys made it really simple to do at home :lol:


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## pepsicola

Just got back from garage having had her serviced, Was advised that I will need to replace Thermostat as the engine is running cool! I have been quoted £180 plus vat doe's this soundabout right? they said it would take a couple of hours as the have to remove the alternator etc.


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## Thundercat

Did mine a few weeks ago and didn't need to remove it. I think it does improve access though. 
It is a DIY job if u fancy having a go?There is an excellent write up by John H, just need to be patient. 
Think of all the money you could save for future mods!


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## pepsicola

Yes I just read the how to but i rarely get the time to tinker under the bonnet myself I just thought The cost seemed a bit steep?


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## Daz8n

pepsicola said:


> Yes I just read the how to but i rarely get the time to tinker under the bonnet myself I just thought The cost seemed a bit steep?


Seems a bit steep to me... thermostat is about £20 and O ring about £2.50!! Two hours labour can't be more than £80 surely???


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## alzibub

Just Booked my 225 BAM into midland VW to have my stat changed, as i have the low temperature reading problem. I have been told it will cost me £65 and take around 3/4Hr. At that money why do it myself


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## John-H

It depends how much you like working on cars, knowing you've done it properly as well as saving the money :wink:


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## TestTT

Was planning on doing this today visited audi dealer for parts got the coolant, o ring, and dipstick guide just incase.
They did not have the thermostat in stock, parts bloke said it was a different one in my tt compared to others and he would have to order it as it has different temp range, can anyone confirm this? he sais it was £20 plus! So went to eurocarparts and and bought one for £8. Just thought i'd ask before fitting,

Car is 2003 225 BAM,

Thanx


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## John-H

From ETKA:
Thermostat P/No: 050 121 113 C Coolant thermostat (87C - 102C) AJQ, APX, APP, AUQ, ARY, BAM, AUM

It's all the same as far as I know. I'd be wary of using non Audi with this one as if it needs replacing again it's a pain.


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## ViperOneZero

Do not fit an after market thermostat.. i fit a QH one and it runs at 95-100c.. Im replacing with a neuspeed... the thermo change procedure is pretty easy to be honest.... .. go OEM or Neuspeed low temp!


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## UK225

Hi,

The dealer was correct, there are both B & C revision thermostats for BAM.

2003 225 will likely have the B part fitted.

B part 80-102deg
C part 87-102deg

Regards
Morgan


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## John-H

Ah yes found that variant now - not seen it before. Seems a BAM can have either specified - I'll add it to the How To.
P/N: 050121 113 B (Marked Yellow) 80C - 102 C

I wonder whether GSF have that information?


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## TestTT

He did check it against my chassis number, a closer look at the euro carparts themostat has 87c engraved into the lip on it, which would be the the c type then and the wrong one for my BAM,

Thanx guys for saving myself alot of aggro, will be going back to dealers for the b type,


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## claven

changed my temp regulator today was a easy job when i found it and it only lost a small amount of anti freeze. Tomorrow going to change thermostat as temp reading at around 60c so i think therm must be stuck open. And then front and back pads as only had car for 2 weeks. Then the big job cam belt pump pressure wheel hope this is ok to do. I have basic engine skill is there any advice on cam belt ;eg Know a good fitter in South near southampton/Bournemouth area . [smiley=book2.gif]


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## zakkiaz

I'm having the same problem, temp is up and down at odd time while running.
son said without a warning light can't do a check to see what is wrong, I'm useing more petrol too.


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## TT DWN UNDER

I have a 2001 and installed the "C" type ..no problems ,sits bang on 90 degrees always...heres an explanation John H gave me on a pm as I had the same question about the "B" and "C' types......cheers

Until model year 2002, 050 121 113 C was the only thermostat installed (AJQ, APX, APP, AUQ, ARY, BAM and AUM) - this is an "87 deg C" part. From 2003 version 050 121 113 B (APX, BAM and BFV) marked with a yellow paint dot, became available - this is an "80 deg C" part. The B part starts to opens a little sooner than the original C part and may be better to keep temperatures down for big turbos etc. On average the C part will keep the engine 90 deg C to 95 deg C as opposed to the B part 87 to 92. Audi will tell you the B part is for 2003 onwards i.e. BAM. Audi may also have introduced it to reduce the on time of the fans as the thermostatic switch on the radiator has a first operation point of around 96 deg C. for half speed and second point of about 104 deg C for full speed. Both will work but the C part will likely last longer as they usually fail by opening too soon.


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## stoffi

Thanks for this guide! I just finished it!

However, it took a LOT longer than anticipated, because the lower radiator hose clamp had been fitted with the clasp up toward the hood, so getting a grip on it was a hellish nightmare and I can recommend what I did to finally solve that issue, should you have it.

I used a jubilee clip which I bent to shape, so as to be able to grab the stupid Audi clamp. I then carefully tightened it until the Audi clamp got loose, which meant that I could twist it around toward me, and in that way work on it like intended.

Another big problem was fitting the lower thermostat housing bolt. I can only say that one should have a lot of fine tools, small flashlights, bits, wrenches n' stuff while doing this job. The dipstick didn't break while doing the job and I didn't need to remove it at all. However, as I had bought one just in case, I thought I might as well just swap the old one for the new one. Pulling upward just shattered the whole thing. It was like as if it had been dipped in liquid nitrogen, as all I had was like 50 shards of plastic in my hand and all over the engine bay.

When I first started the engine, there was a worrying puff of smoke coming from the generator, which smelt like burnt plasic or rubber. Obviously, I shut motor off, but once I started it again it was fine. I'm not sure how it worked, all of this, but 49C is showing correct results, although I'm wagging between 89-94°C. I guess it's fine, but the analogue hand is synced from 0°C up to 80°C, but then it races up to 90 before the 49C-dials and stays there. It doesn't show 94°C when the 49C trick is showing that. I've changed the sensor as well. I'll have to see how it'll turn out.

By the way, I could hear the bubbles filling up throughout the engine bay in the beginning, as I had completely drained the system and flushed it with water several times, until only clear fluids where being drained.

In addition, my cooling fluid tank was full of sand and all kinds of debris, so I disconnected it and constructed an L-shaped brush out of a wooden artist's brush, and agitated the dirt on the inside with detergent. After rinsing it like 40 times it was as good and shiny as new!

As the car is not going up beyond 95°C at it's peak, I'm assuming that this operation worked. Am I right?

Thanks for the guide! Awesome!


----------



## John-H

Yes, sounds like a success. The needle is software weighted, so any real temperature between 80 and 100 will always read 90 to give confidence. Temperatures will vary a little and once warmed up will stay around the levels you've observed.


----------



## claven

zakkiaz said:


> I'm having the same problem, temp is up and down at odd time while running.
> son said without a warning light can't do a check to see what is wrong, I'm useing more petrol too.


 I HAD SAME PROBLEM AND IT WAS DOWN TO A FAULTY TEMP SWITCH AND A FAULTY THERMOSTAT, ONCE I CHANGED THEM NOW ITS FINE SITS AT 90C PERFECT AND OF COURSE BETTER ON FUEL AS COMPUTER NOW IS RUNNING AT CORRECT TEMP AND NOT ON CHOKE WHICH OF COURSE USES MORE FUEL, (WARNING ) WHEN CHANGING THERMOSTSAT YOU WILL DO IT MUCH BETTER WITH A 1/4 INCH SOCKET SET WITH A LONG EXTENSION BAR FOR LOWER BOLT , TOP BOLT EASY. AND TEMP SWITCH ONLY TAKES 10 MINS TOPS, BUT MAKE SURE ENGINE COLD AND LEAVE EXPANSION BOTTLE LID ON SO ANTIFREEZE DOES NOT POUR OUT.


----------



## stoffi

John-H said:


> Yes, sounds like a success. The needle is software weighted, so any real temperature between 80 and 100 will always read 90 to give confidence. Temperatures will vary a little and once warmed up will stay around the levels you've observed.


Thanks! Keep the write-ups coming! They're worth gold!


----------



## l3ttx

Juct been looking at changing my thermostat and notice the dipstick tube is broken, any one got a spare laying around as Audi parts have shut for the day. :twisted: :twisted:

If not am i better to completely removing the tube and i have some rubber bungs that would fit in the hole until i get a new one monday :?: :?:

all help greatly appreciated.


----------



## John-H

Just get some self amalgamating tape from Halfords or B+Q and bind up the split for now.


----------



## l3ttx

thanks for the advise john but is have totaly removed the dip stick as the old unit had nearly snaped all the way around. I anve used a rubber bung and will put some tape around it to keep it in place iam not planning to go far. just to the dealers.

i managed to get hold of audi part just before they closed and have orded me the part in the ya re only £3.98 inc vat i would say this is a essential piece required for doing the thermostat change as you dont want to be stuck like me.


----------



## John-H

It's worth having one as a spare. I may be too late then but a tip for stopping bits falling into the sump, as it usually snaps off leaving an inner ring of crumbley plastic, is to poke the head of a long bolt in and drag out the bits with the underside of the head.


----------



## l3ttx

thanks for the advise, ive used a pair of tweesers and a bent driver. theres not much room though. :roll:

thanks for everyones help today, i managed to get a dipstick tube from Euro Car parts for £3.50 this afternoon, so we are back on the road.

For information the the Audi part number for the stick tube is 06A 103 633B


----------



## l3ttx

After three hours cursing the car I finaly managed to change the theromstat today. Following yesterdays broken oil dipstick. Just got back from a long gentle ride with the needle not moving from straight up (90 deg), and the 49C trick around a constant 88 deg C. All looks to be good but I wont be doing it again.

Another thanks to very one for there help and John for the great insturictions.

Next weeks challange Haldex oil and filter??


----------



## davenearside

Hello all,

So, (deep breath) if a 1999 180 is suffering from slightly elevated fuel consumption, only reasonably warm air on HI (both full blower and low blower), a faulty dashpod reading of no needle movement on the temp display, a reading of 30oC on 49C climate control display and a (possibly irrelevant) reading of 90oC 51C climate control display, what the devil can I assume is wrong with the car?!

I'm wondering if a faulty temp sensor would keep the thermostat open sufficiently for the engine to not get to a decent temperature? Or maybe both the temp sensor and the thermostat are bust...

All thoughts hugely appreciated as I need to sort it given the current UK weather situation!

David


----------



## TTQ2K2

Davenearside: I'd suggest it is a partially stuck-open thermostat.

FWIW, your problem makes this thread a timely update...my thermostat appears stuck open as of Monday, this week. time for a change.

cheers and thanks for bringing this one back up from the dead.

[smiley=cheers.gif] to you, mate.


----------



## davegill79

Cheers or the write up. Finally got round to swapping out the thermostat today. Just a few observations from my experience:

- I didn't bother loosening the oil cooler hose, was a bit worried about getting it back on afterwards. I didn't loose too much fluid, squeezing the hoses a few time to tease some extra out of the sump.
- The lower screw is a complete sod. I had success with a 1/4" 10mm socket with various extension arms. Went in diagonally with the ratchet operated from around the top of the dipstick.
- Don't buy a replacement thermostat from europarts, as they don't supply a sealing ring

Just a simple oil and filter service tomorrow!


----------



## bboyglitch

Fantastic guide! Thank you so much for this!!


----------



## bobbobb

done this today and thanks for the how to, helped a lot

i didnt remove the oil hose but removed the alternator wires made the bottom bolt easier and used various joints and extensions to get to the bottom bolt.

thank you again i didn,t even know where it was before i read this and you do scratch your hands to bits.

OH mine is a 150bhp and a aum engine still the same though the thermostat might be diffrent.


----------



## markypoo

Did mine yesterday, took inlet manifold plates off but left everything else on, including the pipe to the thermostat housing just hooked it round the alternator while I changed the stat. The 1.5l of G12 was bang on 50/50 mix for what I lost as didnt drain either :roll: I did fill a 10mm socket with bluetac for the bottom bolt though, worked a treat


----------



## jas6004

I think my thermostat needs replacing so will have a go at some point, but looking on here, it does make me wonder how p!ss poor these stats must be with the amount of others going faulty.

Jas


----------



## lunavega

Hi,
Super duper write up. Did my thermostat change in about 2 hours, but that was with a lot of flaffing about to ensure I got things right. Was not looking forward to it when it looked like an up from underneath job (what`s that all about?)
The dipstick tube I knew was already broken (my local garage after alternator change but you can`t prove these things can you) so it got replaced.
Bit of a bugger getting the little front cover off as the screws had seized and I had to take out the 2 allen bolts instead. Easy out needed to replace, but that`s a job for another day I think.
Temperature now sits at 90 on gauge and 49c.
Thanks very muchly John.


----------



## davegill79

Regret grumbling at all about this being a bit of a fiddle. Have exactly the same problem on my wife's Mk4 Astra, turns out it's a timing belt off job! Can't wait for that....


----------



## S&amp;S

are the ebay thermostats ok really cant be arsed to go to audi parts or is oem better here?


----------



## alun

i dont think id buy something like this of ebay.. if you want one posted try gsf.


----------



## kadvr6

did my thermostat today, and i ever ever have to take that bloody bottom bolt off again i will cry, it does not help having hands like spades i think lol


----------



## Gazzer

kadvr6 said:


> did my thermostat today, and i ever ever have to take that bloody bottom bolt off again i will cry, it does not help having hands like spades i think lol


ive done same today and yes my hands are ripped to shreds with a permanent squint trying to see that elusive bottom bolt lol

any chance someone has this sort of write up for the 1.8 180 model as i am a novice on doing this due to company cars lol.
but i am trying guys.....


----------



## ViperOneZero

My advice to anyone is buy OEM ( from Audi dealers) or Neuspeed low temp... I went the ebay cheaper route as per my Yorkshire genetics and it failed in no time.


----------



## S&amp;S

thanks for the reply guys got a Audi oem part sitting on the table and some g12++. IS g12++ ok and do i really need distilled water?


----------



## Hoggy

Hi S&S, As I believe you live in a hard water area, in the long term, you would be better off with distilled water, but not essential, depends how long you intend keeping TT. If you happen to have a household dehumidifier, use the water from that, same stuff.
Hoggy.


----------



## steveupton

kadvr6 said:


> did my thermostat today, and i ever ever have to take that bloody bottom bolt off again i will cry, it does not help having hands like spades i think lol


Firstly, the trick with this job is to have a very long extension, I used a long 3/8" with 3/8" to 1/4" adaptor and a 1/4" extension plus a 1/4" universal joint and 1/4" drive 10mm socket. This means that the ratchet handle is well clear of the engine and bodywork and after doing 2 now can guarantee that the job can be done without cursing, getting scraped nuckles etc. If anyone in the Watford area ever needs help doing this job, would be happy to oblige.

Secondly, only ever use Audi stat as they nearly always fail in open position whereas pattern parts can fail in closed position.


----------



## S&amp;S

just done this bottom screw came out nice and easy with a long ball ended allen key


----------



## wazman999

Mine needs doing, does anyone know an independant Audi specialist in SE London / NW Kent? I've fallen out of love with the one man band garage at the end of my road, thanks


----------



## bambam

Hi, This is my first quick post. Just want to thank everyone for their tips on how to do this job and now armed with all this invaluable information i'll be changing mine hopefully within the next week or two.


----------



## GB20280

Thanks John for the excellent guide, did mine today and whilst it was a pig of a job which I'd never want to do again, this guide certainly helped greatly !! Would like to know what tool the stealers use to get that bottom bolt out, took me a good 1.5 hours to undo it and another 20 mins doing it up 

It fixed the problem though, so back into the 90's and a much happier car / driver 

Thanks again John !


----------



## RudeBadger

What would a stealer charge for this job?


----------



## muxgt

Nice write up John-H

Will be using this when I replace my thermostat


----------



## Hoggy

RudeBadger said:


> What would a stealer charge for this job?


Hi, £165 I've seen quoted & about £95 from an Indie.
Hoggy.


----------



## Wak

wazman999 said:


> Mine needs doing, does anyone know an independant Audi specialist in SE London / NW Kent? I've fallen out of love with the one man band garage at the end of my road, thanks


www.4rings.co.uk


----------



## holla_j

Hi Guys

Picked up my new TT today, the guy I bought it off told me he had just had a new thermostat fitted and that since doing so the eninge temp often rises from 90 to around 105 when worked a little harder. It always rights it's self but why is it doing this and should I be replacing this already new thermostat?

Thanks, James


----------



## Wak

holla_j said:


> Hi Guys
> 
> Picked up my new TT today, the guy I bought it off told me he had just had a new thermostat fitted and that since doing so the eninge temp often rises from 90 to around 105 when worked a little harder. It always rights it's self but why is it doing this and should I be replacing this already new thermostat?
> 
> Thanks, James


Fans may be off or not working
Temp sender or 
Perhaps water pump

Suspect fans though

Sent from my iPhone using Tapatalk


----------



## george118

Hi all,

Just done this today, I'm very proud of myself! Took 3 whole hours but I am an idiot.
Would never have manged without this write up so thank you to the OP. 
I would advise anyone looking to do this to buy a new dipstick in advance as its almost certain to shatter into a million pieces.
Also, I didn't drain the whole system as I couldn't find the drain plug so just lost about 1ltr of coolant and topped up after.


----------



## John-H

Well done  I'll have to add a note about brittle dipsticks seeing a they are all getting a bit old these days.


----------



## SilverFoxTT

I had posted in the Mk1 forum before remembering to look here for help (note to self: READ the Knowledge Base!) 
Situation- gauge=90deg, 49C=around 94deg, VAGCOM log of G62=68-72deg
Was told late last year be the garage that changed by cambelt the thermostat had been tested and was working fine.

It seems there is a couple of temperature sensors as quoted-

'Another thing to bear in mind is that there are two temperature sensors in the same screw in sensor unit on the engine. One sensor (G2) feeds the needle gauge and one (G62) feeds the ECU. G2 is also read by the climate control as 49C. There has been some confusion and misinformation about this: 49C does NOT read the ECU sensor and 51C does NOT represent the equivalent of the dashpod software weighted 49C reading. Ignore 51C.' John-H

So I have a perfect dashpod temp guage, matching 49C CC reading and I think all is well. APPARENTLY NOT!
Logging the coolant temp sensor G62 in VAGCOM shows a constant low reading. Bizarre, the ECU is being misinformed by the G62 sensor and my 2 gauges (dashpod & CC) tell me everything is ok.

Can I assume the thermostat is good but the G62 sensor is bad?


----------



## John-H

Perhaps so. What temperature is G62 reading?


----------



## SilverFoxTT

Logged it this morning. With a cold engine G62 readings are ambient temperature as expected. Starting at 20deg, as the engine warms the temp rises as expected, but never gets above 75deg. 
When the 49C reached 90deg the gauge reached 90deg, but the G62 recorded 73deg. 
On inspection, the connector that attaches to the sensor has a cracked outer housing and may be causing some connectivity issues. There was also a small amount of grime around the cable, although the pins and connectors were clean. 
I don't know how to fix this damaged connector as it is part of the wiring harness. Anybody know if there is a repair section available? I'm not likely to find a breakers yard with a TT here! :?

Looking at the Bentley book, it's clear the sensor has 4 pins, two of which supply the G2 and two supplying the G62. From the schematic it does seem the temp sensor housing contains two entirely seperate sensors/switches/potentiometers. I'm concerned this faulty G62 reading will have the ECU alter fueling settings. I'm not concerned about fuel costs, but I am concerned of any damage this false reading may begin to cause.


----------



## John-H

The thing to do is measure the resistance of the sensor - there's a graph of resistance versus temperature in Bentley. I suspect the connector just needs sealing.


----------



## SilverFoxTT

John-H said:


> ... there's a graph of resistance versus temperature in Bentley....


Sorry John-H, can you give me an idea of the page number!???!! I've given the Bentley a 'man-look' and just can't find it. :roll:


----------



## Bre-TT

Hey guys, just a quick double check.

My engine dash reads about 65degs and 49C reads the same. I think this means I need a new sensor, right? Anything else I can check to confirm before I go and order the bits?


















I have the BAM engine, so I think I need part numbers:-

050121 113B (sensor)
038121 119B (sealing ring)
06A 103 633B (oil tube, just in case mine breaks).

Anything else?


----------



## Hoggy

Hi Bre-TT, If Code 49c & gauge read the same low temp, replace the thermostat.
Hoggy.


----------



## Bre-TT

Hoggy said:


> Hi Bre-TT, If Code 49c & gauge read the same low temp, replace the thermostat.
> Hoggy.


Thanks. It's "VauxhallThru&Thru", by the way... JohnH changed my user ID 

Cheers,

Bre-TT.


----------



## John-H

He did ask me to :lol: :wink:

Yes sounds like thermostat.


----------



## Bre-TT

Hoggy said:


> Hi Bre-TT, If Code 49c & gauge read the same low temp, replace the thermostat.
> Hoggy.





John-H said:


> He did ask me to :lol: :wink:
> 
> Yes sounds like thermostat.


Thanks both. Parts ordered, will have a go at changing the thermostat myself I think.

John - I liked the plots at the start of this thread. Is there a 'how to' on producing these anywhere?


----------



## John-H

It's from a Vag-Com log. You just need to select the right measuring blocks and store them in a log file then graph them in Excel.


----------



## aaron_tt

Well read through this guide before going ahead with my thermostat replacement as i too was always getting low temp readings on the dash and the blowers inside never seemed to get that hot. So stayed on late last night to fit a new one and bingo! now getting a steady 90 degrees temp reading when warm  Blimey is that bottom thermostat housing bolt awkward though! :lol: Thanks goes to the OP.


----------



## John-H

You are welcome


----------



## John Stratton

First of all thanks to John H for this Thermostat Change Write up . I have just changed mine and followed this write up with good results . That bottom bolt is certainly a challenge .

I guess we will all find our own method of getting to that bottom bolt but I found using a stubby offset ring spanner and open ended worked best for me . I found that you can see the bottom bolt by looking through the manifold port gap from the top . The key though is getting a good light down there at the correct angle as you can block the light with your hand when going in with the spanner .

All sorted now any way with a reading of 90 degrees on the run on 49c and Dash . I also changed the Sensor .

My reason for changing was a reading of 79 - 82 degrees so the Thermostat was starting to fail .

I hope I never have to change it again but would be alot easier having now done it once.


----------



## Big-Macster

Hi,

Opinion? On my temp dilemma

Seems the 49C test shows i need a new Thermostat. The reading generally Goes to 75C on climate reading and 75 on needle, occasionally going to 90 on the needle with a digital reading of 84C. From page one everything suggests i need a new Thermostat or sensor have interpreted that correctly?

Also how long is it taking you guys on average to change T/STAT? I am mechanically inept so i take my hat off to all of you for even attempting it. How long do you reckon it would take a fully fledged very competent full time mechanic? Hour or so?

Cheers Guys


----------



## TerryCTR

Changed mines today, never again. The bottom bolt went missing in the undertray just as the hailstones came then it wouldn't bite onto the chasis for a good hour at least and that was me having surgeon like hands to get in and hold it in freezing conditions [smiley=bigcry.gif]

I also managed to do it without taking the dipstick guide off but it did split when putting the plate back on so lucky I have a spare to change tomorrow.

It is indeed easier removing the 2 bolts that hold the alternator wire in place shown below










Putting it back though took a lot of patience and isn't something I want to do again so thankfully it now gets up to temp and stays around 88-92 on the aircon reading


----------



## Trouble4

Audi recommends changing the thermostat housing whenever changing thermostat do not know if I missed this in reading this thread and of course removing the dipstick tube and dipstick would never be a problem if you had a Billet Aluminium one from WhanAB.....  ........

What would you think of the thermostat housing in Billet Aluminium ??????


----------



## TerryCTR

I haven't noticed that on any of the guides, I can't see why the housing would need changed. It's on now and its not coming off :lol:

Yes I've saw the billet ones, very nice but also a lot more cash when at the end of the day I don't plan to be changing the stat again in my ownership so I just went for the cheap oem effort


----------



## viakruzis

Thanks for the tutorial pal, i will do it this weekend.

[smiley=fireman.gif]


----------



## Shootist

I started this job on Saturday and did it all from above without the car on ramps or removing the under engine panel. I struggled badly with removing the lower bolt with tools I had and for the life of me could not do up the lower bolt for love or money until I saw this kit on offer and bought it.

http://www.halfords.com/webapp/wcs/..._productId_818451_langId_-1_categoryId_255215

The ratchet moves in 8 degree steps and the sockets have a 30 degree play on them so it was as easy as just putting the 10mm socket on, putting the ratchet vertically in the gap and rocking it back and forth to ratchet it up. What I had struggled to do for 7 hours took me less than a couple of minutes once I had this kit - I really could not believe how easy it made the job.


----------



## John-H

A good tool makes all the difference. You can get also 72 tooth ratchets as well.


----------



## Shootist

John-H said:


> A good tool makes all the difference. You can get also 72 tooth ratchets as well.


Yes, I had a great 1/2 and 3/8 socket set but with the limited space I just could not get the socket on the bolt head in a way in which I could remove or tighten it. A friend came over with a cheap 1/4 ratchet and extension and that was good enough to loosen the bolt but would do nothing to tighten it back up. At the time of buying the kit from Halfords I did not know if it would be any better suited but it made the job a piece of cake.


----------



## joeplease

i changed the temp sensor on my last month, still threw up temps way below what they should have been- changed the thermostat and all was good. fast forward and im getting lower readings again, around the 77-80 mark.
guessing its the sensor again ?


----------



## Shootist

Well if it isnt the thermostat then very likely the sensor and lets be honest they are a lot easier to replace.


----------



## Hoggy

joeplease said:


> i changed the temp sensor on my last month, still threw up temps way below what they should have been- changed the thermostat and all was good. fast forward and im getting lower readings again, around the 77-80 mark.
> guessing its the sensor again ?


Hi Joe, Is that reading from Code 49c. Unlikely to be the temp sensor, but cheaper & easier than thermostat. 
Was it an OEM thermostat ?.I would suspect an 82 degree thermostat fitted & not closing fully.
Hoggy.


----------



## joeplease

Hoggy said:


> joeplease said:
> 
> 
> 
> i changed the temp sensor on my last month, still threw up temps way below what they should have been- changed the thermostat and all was good. fast forward and im getting lower readings again, around the 77-80 mark.
> guessing its the sensor again ?
> 
> 
> 
> Hi Joe, Is that reading from Code 49c. Unlikely to be the temp sensor, but cheaper & easier than thermostat.
> Was it an OEM thermostat ?.I would suspect an 82 degree thermostat fitted & not closing fully.
> Hoggy.
Click to expand...

yep 49c reading, im almost 100% sure it was a genuine thermostat, will have to ask my dad. I thought 90 degree thermostats were a standard so to speak?


----------



## Hoggy

Hi, Up to 2003 an 87 degree was fitted, 2003 on wards an 82 degree was fitted, but unless doing lots of track days then an 87 could be fitted to the TT. Which ever is fitted yours is failing I'm sure, but try sensor 1st as cheaper & easy. 
Hoggy.


----------



## thebluemax

Shootist said:


> I started this job on Saturday and did it all from above without the car on ramps or removing the under engine panel. I struggled badly with removing the lower bolt with tools I had and for the life of me could not do up the lower bolt for love or money until I saw this kit on offer and bought it.
> 
> http://www.halfords.com/webapp/wcs/..._productId_818451_langId_-1_categoryId_255215
> 
> The ratchet moves in 8 degree steps and the sockets have a 30 degree play on them so it was as easy as just putting the 10mm socket on, putting the ratchet vertically in the gap and rocking it back and forth to ratchet it up. What I had struggled to do for 7 hours took me less than a couple of minutes once I had this kit - I really could not believe how easy it made the job.


shootist, I an in dudley and need my stat doing, any chance of some help as you have done it before and have the kit ?

Allen.


----------



## joeplease

Hoggy said:


> Hi, Up to 2003 an 87 degree was fitted, 2003 on wards an 82 degree was fitted, but unless doing lots of track days then an 87 could be fitted to the TT. Which ever is fitted yours is failing I'm sure, but try sensor 1st as cheaper & easy.
> Hoggy.


Ah okay that's interesting mines a y reg so it should have the 87 one then . Yeah your right that's next to do, 10x easier than the thermostat too !


----------



## John-H

You could also try measuring the coolant temperature with a thermometer.


----------



## mixmaster

Replaced the thermostat on my APX engine. John's guide is great to the word; However, I cut corners and didn't drain the coolant at the oil cooler. On removing the old thermostat I lost maybe 2 litres and wouldn't recommend skimping on this. Hindsight is a wonderful thing!

I have used plain water to wash off any area on the block that may have contacted the spilling coolant; Could someone advise how corrosive (if at all) G12 is and if I should worry about cleaning it more?

For what it's worth I found having a head torch, magnetic pick-up and 5mm allen-key were worthy additions to that mentioned already.


----------



## Skeee

http://www.blauparts.com/audi/audi_flui ... luid.shtml

Still haven't found the actual Data Sheet for G12 or G12+ yet. :roll:

If it were I then I'd spray the area with clean water to dilute and drain it away.

http://forums.audiworld.com/showthread.php?t=1856836 and 
http://www.valvoline.com/international/ ... technology for Data Sheet.


----------



## Hoggy

Hi, G12 is not corrosive at all, it's flowing around the inside of the engine & protects against corrosion. 
It won't do the paintwork any good, but will not cause any probs on engine unpainted metals.
Hoggy.


----------



## Skeee

Hoggy said:


> Hi, G12 is not corrosive at all, it's flowing around the inside of the engine & protects against corrosion.
> It won't do the paintwork any good, but will not cause any probs on engine unpainted metals.
> Hoggy.


 I was just about to come to that conclusion:- http://www.carsforum.co.il/vb/attachmen ... 1190799759 To Download the Glysantin 30 PDF Safety Data Sheet,


----------



## Hoggy

Skeee said:


> Hoggy said:
> 
> 
> 
> Hi, G12 is not corrosive at all, it's flowing around the inside of the engine & protects against corrosion.
> It won't do the paintwork any good, but will not cause any probs on engine unpainted metals.
> Hoggy.
> 
> 
> 
> I was just about to come to that conclusion:- http://www.carsforum.co.il/vb/attachmen ... 1190799759
Click to expand...

Hi Skee, Too late again... :lol: :lol: :wink: :wink: 
Hoggy.


----------



## Skeee

Hoggy said:


> Skeee said:
> 
> 
> 
> 
> 
> Hoggy said:
> 
> 
> 
> Hi, G12 is not corrosive at all, it's flowing around the inside of the engine & protects against corrosion.
> It won't do the paintwork any good, but will not cause any probs on engine unpainted metals.
> Hoggy.
> 
> 
> 
> I was just about to come to that conclusion:- http://www.carsforum.co.il/vb/attachmen ... 1190799759
> 
> Click to expand...
> 
> Hi Skee, Too late again... :lol: :lol: :wink: :wink:
> Hoggy.
Click to expand...

Must type faster! :roll: It's because I'm reading and learning it first and not just typing from memory!  :lol:


----------



## Hoggy

Hi Skee, When you are as old as me, plenty of memory to hold all that info, at the moment I can still remember most of it & still type fast enough. :lol: :wink: 
Hoggy.


----------



## Skeee

:lol:

Am also distracted watching ITV4, The Revival, again. _All the bits I missed when I was there_.


----------



## Hoggy

Skeee said:


> :lol:
> 
> Am also distracted watching ITV4, The Revival, again.


Hi Skee, Yes, been watching myself, brilliant racing from the old & expensive cars. 8) 
Hoggy.


----------



## mixmaster

Hoggy said:


> Skeee said:
> 
> 
> 
> :lol:
> 
> Am also distracted watching ITV4, The Revival, again.
> 
> 
> 
> Hi Skee, Yes, been watching myself, brilliant racing from the old & expensive cars. 8)
> Hoggy.
Click to expand...

Hoggy, Skeee - just before you get distracted or forget again thanks for the help. Appreciated. Have a good evening. I'm off to find a guide on changing the plugs...


----------



## Skeee

Plugs are easy. Although must admit this car has the most difficult plugs I've ever done as there's lots to remove first!
Torque setting is 30Nm (I think, I'll check) approx hand tight and and one sixteenth of a turn if you don't have a torque wrench but will check that also. Plug gap is 0.8mm for the OEM plugs but these are usually pre-gapped but no harm in checking.

I always run the new plug through once with a tiny bit of copperslip at the centre and top half of the thread then clean and refit.

Edit:- OEM plugs for the 225 are 30Nm and 0.8mm gap. 

30Nm is approx 22ft lbs.
Without a Torque Wrench:- http://www.pepboys.com/car_care_corner/ ... d_removal/
*
The Wak Guide*
http://wak-tt.com/225sparkplugs/225sparkplugs.htm


----------



## TomQS

Mines been playing up since i had the car. Changed it and my average mpg has gone from 29 to 33.. 8)


----------



## reece1591

Need to do mine as playing up, am I better to get standard Audi part or is the neuspeed one good as seen them on eBay for £25 posted and guessing Audi will charge the same price as that.


----------



## John-H

Stick to the Audi standard part. There's risk in changing and the Audi part comes with warranty


----------



## reece1591

Anyone know the going rate Audi charge for the thermostat??


----------



## reece1591

For anyone who is doing this Audi current rate for thermostat and o ring comes in at £30 and some pence.

Looking to change mine tomo and want to do as little as possible as weather will be really bad no doubt so don't want to be draining whole system etc. As only had a service 2 months ago and it was changed then anyways.

Will it be a case of undo the 2 bolts on the plastic plate above the dip stick pull pipe off the thermostat housing let whatever coolent come out change thermostat over put housing back on pipes then fill up with coolant???


----------



## dcrutt

make sure you have a spare dip stick tube handy as i changed my thermostat last weekend and i only undone the two bolts holding the bracket and it snapped off


----------



## John-H

It's all explained in the first post but you missed out the difficult bit about the bolts on the thermostat housing and the dip stick can be brittle and break if you are not careful. You could save some time by not draining and saving the coolant but when you take the thermostat out it will drain out all of a sudden regardless and you'll have to replace the coolant so you'll need to buy some G12++ and some distilled water to mix.


----------



## reece1591

Yeah already expecting the bolts to be a pain and will get a dip stick when collect rest of bits in the morning.

I already have some coolant so can fill it up just not enough to flush whole system.


----------



## reece1591

Them troublesome bolts won't undo I can get onto them just so so so tight its unreal any ideas people contemplating smashing up the housing and buying a new one at this stage


----------



## John-H

Allen key, 10mm ring, 10mm open end, 1/4" drive socket with UJ, take voltage regulator off alternator etc and no swearing would be my advice :wink:


----------



## reece1591

Bottom bolt off that was super easy with alternator wires out the way that top bolt so so so tight still and rounded off now that's how tight don't know why so now only got access with Allen key which is hard to get leverage on due to angle that it sits at.

Apologies for foul language


----------



## milanonick

reece1591 said:


> Bottom bolt off that was super easy with alternator wires out the way that top bolt so so so tight still and rounded off now that's how tight don't know why so now only got access with Allen key which is hard to get leverage on due to angle that it sits at.
> 
> Apologies for foul language


I found a long ball ended allen key with the ring spanner method worked the best for me.

Good luck.


----------



## reece1591

I gave up lol put it all back together before I really brake something going to buy a 5mm Allen key socket attatchment as its done up so so tight that's the only way I will get it off I think


----------



## Emoe

Thermostat on the 1.8t

Had loads of people saying they're a bee hatch, but in reality it was so simple!

Remove all the plastics from the slam panel
Remove the small trim panel on the dipstick bracket.
Remove the plug on the inlet manifold.
Remove the dipstick bracket with the two Allen keys,
IMPORTANT
spray a liberal amount of wd40 on the dipstick mount and go have a cuppa.
Using careful hand pressure, wiggle the dipstick out. DONT USE PLIERS OR TOOLS!!
You now have access to the thermostat housing......kinda.

Undo the clip on the hose, and pull the hose off, you may as well drain the system and flush it at this point it's not worth the hassle of trying to save coolant coming out. If it's fairly new G12 then catch it to refill.
There's an 8mm nut holding the wiring to the alternator, remove nut and carefully move the wiring upwards, you're not disconnecting the wiring just the cable clamp.
Using 1/4 drive, extension and a wobble bar, remove the two 10mm bolts holding the thermostat housing on.
These are special M7 x 1mm bolts, so don't loose them!!
Remove old thermostat and rubber gasket. 
I normally undo the drain on the near side bottom of the radiator and then flush through the whole system with the hose.

Put the new thermostat in place, with the body inwards, then apply a liberal,amount of grease to the new o ring rubber gasket.
Now place the first bolt on the bottom hole of the housing, put the socket on it, and place into the engine. Give it a few turns to secure.
Now fit the upper bolt. Do both up and refit the m8 nut on the cable clamp.
Pipe on, brackets all back on, and refill the system
Remember to do the drain up on the rad.

If you disconnect the battery, you may find that both fans come on, and stay on when the engine starts, which isn't great for trying to warm the engine to get the new thermostat to open and bleed!
If you don't have a Vag tool, unplug both fan connectors AND the rad fan switch. Start the engine. 
Once the car has warmed and you have bled the system, you can stop the engine, plug the plugs back in, and you should be ok again.

Hope that helps! I did mine on my drive took an hour with the oil change at the same time.


----------



## leescooby

Hi all, buy a screw driver with the Allen key head
Not sure what they're called but makes the bottom bolt a piece of cake

Lee


----------



## DarylFarmer

gt russell said:


> *fantastic and well detailed John, I will be doing mine soon, its good reading how other people learn from mistakes ie the hose on the oil cooler, thats one ill remember. Cheers John :wink:
> Year 2000 Silver 225 TT Coupe / Forge 007p / Xenons / Black Alcantara / Scarlet red Calipers and 5 B.A.P. ( Billion Ant Power ) and accessary socket in boot, and now Sat Nav, Vag-Com,and fixed climate control rattle, cd changer, aero twins, ATE clutch master , Cam chain Tensioner and solar panel battery charger*


It was fantastic information for sure especially for new comers like me.. Everything is mentioned in detail so cheers


----------



## bobclive22

These are good pics and method.

viewtopic.php?f=2&t=475714


----------



## poor1

Excluding removing the skid plate to drain and refill - about an hour all in - easy with a selection of quarter drive wobble extensions and a 10mm socket. When refitting use the top bolt first without tightening it down fully then guide the bottom bolt into it's location with a long extension magnet - no bruised and cut hands. Torque to 15 NM.

Disconnect battery and remove alternator cable for better access.

The dip stick guide tube will inevitably break so have a new one to hand before starting. Don't bother with the ones off Ebay. The OEM part from Audi is only about £3.00 and it fits properley.

It's also worth having a new housing and a couple of new bolts to hand as well - they are only about £3.00 from Audi.

Drain from the draining point at the bottom of the radiator. If on a cold engine the thermostat is closed as it should be and it stays in place when the housing is removed, be prepared for a deluge of coolant when it's released.


----------



## hannakournikova

has anyone got a guide with working pictures?


----------



## Pugwash69

I worked from the downloadable documents on the first post of this thread: 
viewtopic.php?f=2&t=475714


----------



## Bago47

DO NOT REMOVE THE PIPE THAT'S HELD ONTO THE THERMOSTAT HOUSING!!!!

It's absolutely unnecessary and it's PITA to refit without proper tools...


----------



## John-H

I noticed a lot of the pictures were missing so I've reloaded them onto the forum so should be safer than ImageShack which seems to be dropping off pictures. What a pain.


----------



## Bago47

Bago47 said:


> DO NOT REMOVE THE PIPE THAT'S HELD ONTO THE THERMOSTAT HOUSING!!!!
> 
> It's absolutely unnecessary and it's PITA to refit without proper tools...


This is the step I was talking about FYI:









Skipping this step saved me at least 15mins.


----------



## HarveyTT

My temp gauge in the dash has always read low, at 75C however doing the 49C test the temp reads 90C. Sometimes the needle goes up to 90c but it's majority down at 75C. Does that mean I need to replace the sensor or I have a faulty dash pod? 
54plate TT

Auto Vision Detailing
Leeds/Bradford area
[email protected]


----------



## Hoggy

Hi Harvey, Some do the Code 49c test using Code 51c, really :? :? . Code 51c will always show 90 regardless.
Hoggy.


----------



## HarveyTT

I have seen that test climb and sit around the correct temp.

Worth getting the mechanic to sort this when they put in cruise control?

Auto Vision Detailing
Leeds/Bradford area
[email protected]


----------



## Hoggy

Hi Harvey, What has Cruise Control got to do with it. If *Code 49c* on Climate Control shows 90ish during normal driving & dash shows 75, then dash pod is faulty. 
Hoggy.


----------



## HarveyTT

Getting cruise control retro fitted next week so thought I could kill two birds. Be it a faulty dash pod, would this fall under the recall Audi did in regards to the dash pods?

Auto Vision Detailing
Leeds/Bradford area
[email protected]


----------



## Hoggy

HarveyTT said:


> Getting cruise control retro fitted next week so thought I could kill two birds. Be it a faulty dash pod, would this fall under the recall Audi did in regards to the dash pods?
> 
> Auto Vision Detailing
> Leeds/Bradford area
> [email protected]


Hi, Audi never did an actual recall on DashPods. 
Years ago after WatchDog Prog, if you had full Audi dealer history & owned from new, you may have stood a chance, but very unlikely know.
Hoggy.


----------



## HarveyTT

Darn, best live with it then.

Auto Vision Detailing
Leeds/Bradford area
[email protected]


----------



## Trig

> .... 49C = 75 deg C. then the dashpod should read 75 deg C.
> .... 49C = 75 deg C. and the dashpod = 75 deg C. then you have either a faulty sensor or thermostat


Are these two lines not the same?

"49C = 75 deg C. then the dashpod should read 75 deg C. If it does then you have either a faulty sensor or thermostat"

Seems to me that the TT takes longer than it should to warm up, was thinking thermostat, this 49oC test will tell me dashpod/sensor/thermostat..


----------



## Hoggy

Hi Trig, Code 49c is coolant temp. If Code 49c shows 75 then dash gauge should show 75 ish. 
If it doesn't rise above 75 during normal driving then usually thermostat, but of course could be a faulty coolant temp sensor.
If hot engine is left idling & temp rises to 90 (airCon off) then that confirms it's the thermostat.

Dash gauge is weighted to read 90 when actual coolant is anywhere between 82 & 98.

http://www.wak-tt.com/tempsensor/tempsensor.htm

Hoggy.


----------



## John-H

Trig said:


> .... 49C = 75 deg C. then the dashpod should read 75 deg C.
> .... 49C = 75 deg C. and the dashpod = 75 deg C. then you have either a faulty sensor or thermostat
> 
> 
> 
> Are these two lines not the same?
> 
> "49C = 75 deg C. then the dashpod should read 75 deg C. If it does then you have either a faulty sensor or thermostat"
> 
> Seems to me that the TT takes longer than it should to warm up, was thinking thermostat, this 49oC test will tell me dashpod/sensor/thermostat..
Click to expand...

I had to read that twice myself - what it means is ...



> .... 49C = 75 deg C. then the dashpod should read 75 deg C.


Dashpod should read the same as sensor indicates outside the weighted to 90 zone ...



> .... 49C = 75 deg C. and the dashpod = 75 deg C. then you have either a faulty sensor or thermostat


75 deg C for a working temperature is clearly wrong (should be ~90 deg C) so either the sensor is telling lies or the thermostat isn't regulating properly.

P.S. I've made it a little clearer


----------



## Wak

John-H said:


> Trig said:
> 
> 
> 
> 
> 
> 
> .... 49C = 75 deg C. then the dashpod should read 75 deg C.
> .... 49C = 75 deg C. and the dashpod = 75 deg C. then you have either a faulty sensor or thermostat
> 
> 
> 
> Are these two lines not the same?
> 
> "49C = 75 deg C. then the dashpod should read 75 deg C. If it does then you have either a faulty sensor or thermostat"
> 
> Seems to me that the TT takes longer than it should to warm up, was thinking thermostat, this 49oC test will tell me dashpod/sensor/thermostat..
> 
> Click to expand...
> 
> I had to read that twice myself - what it means is ...
> 
> 
> 
> 
> .... 49C = 75 deg C. then the dashpod should read 75 deg C.
> 
> Click to expand...
> 
> Dashpod should read the same as sensor indicates outside the weighted to 90 zone ...
> 
> 
> 
> 
> .... 49C = 75 deg C. and the dashpod = 75 deg C. then you have either a faulty sensor or thermostat
> 
> Click to expand...
> 
> 75 deg C for a working temperature is clearly wrong (should be ~90 deg C) so either the sensor is telling lies or the thermostat isn't regulating properly.
> 
> P.S. I've made it a little clearer
Click to expand...

I think not John, you've basically said that you cant trust the dash because the temp sensor may be faulty in a very elaborate way! :roll:



> .... 49C = 75 deg C. then the dashpod should read 75 deg C.


1. If the dash does not read the same as the 49C or is not on 90 when 49C >79 and <100 then this indicates a faulty dash.

2. Using vagcom/vcds on ecu on block 001 if the coolant temp is circa +/-7 degrees different to 49C then the temp sensor outputs are diverging and it should be changed.

3. If the ecu(001) and 49C outputs are in sync and the car is running < 80 when constant speed driving then its 99% a thermostat needed.

3a. to Check 3 above you need an independant temp probe into the expansion tank.... if 49C is showing 75 ( or a high figure) degrees and the actual coolant temp is 85-90 in the bottle then this would suggest a faulty temp sensor which doesnt fit criteria 2 above as both outputs are both giving a false reading.
(This condition is however very rare that both temp outputs are false hence the 99% thermostat certainty)

3b. the laymens check for a faulty thermostat without a temp probe, is if it is genuinely running cool and you pull up and carefully open the expansion bottle it will bubble less and not flow out at 75 degrees than if it were running 90 degrees under pressure where it would usually bubble up and try to force some coolant out. ( remember I said open gently! )


----------



## John-H

Wak said:


> I think not John, you've basically said that you cant trust the dash because the temp sensor may be faulty in a very elaborate way! :roll:
> 
> 
> 
> 
> .... 49C = 75 deg C. then the dashpod should read 75 deg C.
> 
> 
> 
> 1. If the dash does not read the same as the 49C or is not on 90 when 49C >79 and <100 then this indicates a faulty dash.
> 
> 2. Using vagcom/vcds on ecu on block 001 if the coolant temp is circa +/-7 degrees different to 49C then the temp sensor outputs are diverging and it should be changed.
> 
> 3. If the ecu(001) and 49C outputs are in sync and the car is running < 80 when constant speed driving then its 99% a thermostat needed.
> 
> 3a. to Check 3 above you need an independant temp probe into the expansion tank.... if 49C is showing 75 ( or a high figure) degrees and the actual coolant temp is 85-90 in the bottle then this would suggest a faulty temp sensor which doesnt fit criteria 2 above as both outputs are both giving a false reading.
> (This condition is however very rare that both temp outputs are false hence the 99% thermostat certainty)
> 
> 3b. the laymens check for a faulty thermostat without a temp probe, is if it is genuinely running cool and you pull up and carefully open the expansion bottle it will bubble less and not flow out at 75 degrees than if it were running 90 degrees under pressure where it would usually bubble up and try to force some coolant out. ( remember I said open gently! )
Click to expand...

Hi Wak,

I'm not quite sure what your "thinking not" refers to - the How to was trying to include the possibility of a dashpod fault, a sensor and a thermostat fault so was giving some likely examples to aid understanding and says...



> If the two readings (dashpod temperature needle, and 49C) agree, then it rules out the possibility that your dashpod is at fault which can happen! Bear in mind the software weighting. Here are some examples:
> 
> .... 49C = 82° C. then the dashpod should read 90° C. (weighted to appear running normal 90° C.)
> .... 49C = 75° C. then the dashpod should read 75° C. (should tell raw truth)
> .... 49C = 105° C. then the dashpod should read 105° C. (should tell raw truth)
> .... 49C = 90° C. and the dashpod = 100° C. then you have a faulty dashpod
> .... 49C = 93° C. and the dashpod = 80° C then you have a faulty dashpod
> .... 49C = 75° C. and the dashpod = 75° C. then you have either a faulty sensor or thermostat (should run 90° C).
> 
> If your temperature is low, e.g. 75° C. then this generally indicates you need a new thermostat and it's sticking open. You can often see the temperature fall on a long overrun when no petrol is being burnt but the radiator is still cooling the engine. BUT check the water temperature with a thermometer to confirm the water temperature is real and not a faulty sensor!


I don't think there is anything wrong with that is there or have I missed something? It's basically the same as I wrote it originally - I've just added the bits in brackets to help clarify. I could add in your detail about block 001 but initially I was not trying to require anyone to use Vag-Com to analyse where the fault was likely to be. Thanks for any suggestions.


----------



## Wak

Hi John, 
I was refering to your making your two statements clearer, they both showed the same thing but one suggested that the temp sender could be at fault hence its no clearer in either case if the 49c/dash behaviour is identical, you trust the display or you dont hence:-
The points I raised were the process to help confirm and narrow down what is the fault, an invaluable tool is a probe like this.
http://www.maplin.co.uk/p/ht-wide-range ... eter-l55an

pretty cheap and lets you confirm expansion tank temperature although keep a view that its around 5 degrees cooler than what the sensor may see near the block.

You dont neccesarily need vagcom/vcds 
A. because sensor output deviation is a ecu managed fault that will trigger a eml once its really bad. 
B. Its relatively rare and rubust if your upgraded to green sensor so have faith its 49C output is accurate.
C. the cheaper temp probe option will give relative confidence on a diagnostic of the 49C value vs the view of a sensor or thermostat fault by checking the actual coolant temp.


----------



## asahartz

As suspected I need a new thermostat. The temperature gauge has never gone to 90 since I've had the car, so I did the 49c check today on my drive home; it was warm outside but the temperature never went over 66, and the dashpod matched the climatronic display right through.

Ah well, no biggie. I'll get that done when my holiday starts.


----------



## John-H

You followed it then  . I've changed the order to put the two 75° C lines together and added a "...but..." which highlights the dashpod correct behaviour and likely implication of a low temperature reading. I already mentioned the thermometer in the last line 



> If the two readings (dashpod temperature needle, and 49C) agree, then it rules out the possibility that your dashpod is at fault which can happen! Bear in mind the software weighting. Here are some examples:
> 
> .... 49C = 82° C. then the dashpod should read 90° C. (weighted to appear running normal 90° C.)
> .... 49C = 105° C. then the dashpod should read 105° C. (should tell raw truth)
> .... 49C = 90° C. and the dashpod = 100° C. then you have a faulty dashpod
> .... 49C = 93° C. and the dashpod = 80° C then you have a faulty dashpod
> .... 49C = 75° C. then the dashpod should read 75° C. (should tell raw truth) ... but ...
> .... 49C = 75° C. and the dashpod = 75° C. then you have either a faulty sensor or thermostat (should run 90° C).
> 
> If your temperature is low, e.g. 75° C. then this generally indicates you need a new thermostat and it's sticking open. You can often see the temperature fall on a long overrun when no petrol is being burnt but the radiator is still cooling the engine. BUT check the water temperature with a thermometer to confirm the water temperature is real and not a faulty sensor!


----------



## ryang360

hi, today I had the engine management light come ,code p1296 think its the thermostat,how much is this normally at a local garage? any recommended garages in the Swansea area?


----------



## Wak

ryang360 said:


> hi, today I had the engine management light come ,code p1296 think its the thermostat,how much is this normally at a local garage? any recommended garages in the Swansea area?


http://www.wak-tt.com/tempsensor/tempsensor.htm


----------



## ryang360

thanks wak, would the code just be the sensor then? have done the 49c and its showing the same reading as the dash 76-80


----------



## Hoggy

Hi ryang, You could change the sensor first, cheap & easy, but I would expect thermostat to be faulty & causing low coolant temp. Dash gauge/indicator should show much the same as code 49c until it reaches 82 ish & gauge/indicator will then show 90 as it's weighted. 
Hoggy.


----------



## bobclive22

Wak says,

_3a. to Check 3 above you need an independant temp probe into the expansion tank..._.

Like my suggested meat thermometer probe, it has always seemed to me the logical first step was to check the water temp independently of the Audi electronics before spending your cash.


----------



## Hoggy

Hi, Cheap enough & I will purchase one just to see how much temp difference there is between reservoir & coolant sensor when engine off & cooled enough to remove cap, when sensor is giving correct reading.

http://www.ebay.co.uk/itm/NEW-DIGITAL-K ... 5416344c6d

Hoggy.


----------



## bobclive22

Hi Hoggy,

About £1.90 off ebay.

The whole idea though is to obtain an *independent accurate water temp reading*, the dash I believe can show 90 when temp from sensor is reading between 82 and 100, so you cannot compare the probe in the header tank reading with the sensor reading as you don`t know if the sensor is reading the correct temp in the first place, I think. Wak states there is a 5 degree difference between coolant in header tank and coolant near sensor on engine. In my case 49 says 98, probe says 91 and dash says 90, I still have the emission light on but as everything appears OK it can stay on.

http://www.ebay.co.uk/itm/NEW-PRACTICAL ... 1269832570


----------



## John-H

The bottle will always be less than the engine core. There's minimal flow into there. After the engine has been fully warmed and following some revs to circulate the coolant, the closest the bottle/core/sensor will be to each other.

Idling for a while with low flow rate will cause these points to differ in temperature. Opening the cap immediately after revving the engine for a while risks boiling over however. Opening the cap slowly when the engine has returned to idle minimises the risk. You may well get coolant bubbling into the header tank so be careful! The headertank will likely fill to the brim - watch it doesn't overflow! If you can get the cap off without a major scalding stream explosion - this is the moment that all these temperature points of interest will be closest. You need to be careful!

It's better to err on the side of caution and instead expect a few degrees difference.

If you really want accuracy, modify a cap and seal in a thermometer probe. Then tell us what the difference is :wink:


----------



## Boruki

Thanks for this John - I managed to get this done in under 2 hours (excluding a couple of silly things on my part).


----------



## Stevie Jinx

Many thanks for this write up John  
My gauge has been sat at the cool end of the dial and although i swapped the temp sensor, it made zero difference.
My next move now, on Friday when it arrives in the post, is to swap over the thermostat. I have had a look at the car itself and am all set to remove the old one and replace it. Hope this solves the problem. 
1st class write up as i said though, many thanks.


----------



## bobclive22

John,

In the old days engines boiled over on a regular basis, I have refilled my rad with water from a live stock drinking trough situated in a farmers field. Most motorist were aware there was a possibility of getting scalded if the rad cap was taken off while hot without due care. It takes only *1 full turn* to remove the rad cap as against *5 full turns to remove the Audi header tank cap*, the pressure in the header tank cap starts to release on the first turn and is easily controlled if done slowly. If you place a thick rag between your hand and the header tank top it is safe, if you panic just re-tighten the cap.

The probe Wak uses like mine needs the header tank top to be removed at temperature, It`s the *only way *to obtain an *independent temperature reading,* at least having that reading you know where you stand at the start.

ie if the probe in header tank reads 80ish but the gauge shows 60ish it aint the stat thats at fault.


----------



## John-H

Yes, the header tank cap design is far far safer than the old metal quarter of a turn and it's off design of radiator cap and the overflow is directed away from you anyway. You have to play safe with safety advice though. I don't want to end up in hot water  

Hopefully this discussion had given the right realistic information as well as adequate warning :wink:

The point I was making was that only when the coolant has been recently circulated is it in thermal equilibrium from averaging - if the flow stagnates it equalises with its immediate surroundings and then you get differences.


----------



## Stevie Jinx

Well,
I pulled the temp sensor out the other day as i said and it didn't improve the dial. It's still sat in the cold mark at 50,
New sensor,( green one a opposed to the older black one,) installed.
Today i pulled the thermostat out too, new one should be here via the internet by Friday.
I flushed the entire cooling system out till it ran clear and will top up again with the proper coolant and deionised water, then bleed it etc.
Hoping this will at last make the needle climb !
If not am i looking at a water pump problem ?  
*The new temp sensor*

*The old thermostat.*



*Curious thing is:*
I placed this thermostat, the old one...in a saucepan full of boiling water and it worked ?
Opened when hot and closed when cooled by tap water ?
Confused now as to why the gauge needle isn't really moving ? :?:


----------



## Hoggy

Hi, It won't be the water pump as that would cause high coolant temps. Even with stat stuck open I would expect Coolant temp to rise above 50. Looks like a connection/dashpod prob to me, but try new OEM stat first.
Hoggy.


----------



## Stevie Jinx

Hoggy said:


> Hi, It won't be the water pump as that would cause high coolant temps. Even with stat stuck open I would expect Coolant temp to rise above 50. Looks like a connection/dashpod prob to me, but try new OEM stat first.
> Hoggy.


Will do Hoggy. Cheers pal


----------



## bobclive22

If you had known the temp of the engine coolant at the start you would have known exactly which item to change instead of just guessing.


----------



## Stevie Jinx

bobclive22 said:


> If you had known the temp of the engine coolant at the start you would have known exactly which item to change instead of just guessing.


If i'd known what part to change i wouldn't have had to guess at all !


----------



## Hoggy

bobclive22 said:


> If you had known the temp of the engine coolant at the start you would have known exactly which item to change instead of just guessing.


Hi, Steve had replaced coolant sensor 1st, not every one has meat thermometer or similar like us.
http://www.ebay.co.uk/itm/NEW-PRACTICAL ... rmvSB=true
Hoggy.


----------



## Stevie Jinx

Hoggy said:


> bobclive22 said:
> 
> 
> 
> If you had known the temp of the engine coolant at the start you would have known exactly which item to change instead of just guessing.
> 
> 
> 
> Hi, Steve had replaced coolant sensor 1st, not every one has meat thermometer or similar like us.
> http://www.ebay.co.uk/itm/NEW-PRACTICAL ... rmvSB=true
> Hoggy.
Click to expand...

Cheers hoggy,
Was just thinking there how i would check that lol


----------



## Hoggy

Hi Stevie, Once engine cool enough to remove cap on reservoir, insert thermometer, it will give lower reading than Code 49c but will give some idea of coolant temp. But I would expect it to be higher than 50 degrees & yours is not even reaching 50.
Have you used Code 49c on Climate Control ? Click link,follow instructions




Hoggy.


----------



## Stevie Jinx

Hoggy said:


> Hi Stevie, Once engine cool enough to remove cap on reservoir, insert thermometer, it will give lower reading than Code 49c but will give some idea of coolant temp. But I would expect it to be higher than 50 degrees & yours is not even reaching 50.
> Have you used Code 49c on Climate Control ? Click link,follow instructions
> 
> 
> 
> 
> Hoggy.


Havn't really tried anything mate to be honest !
Just thought perhaps it was the sensor so fitted a new one with no results.
So thought then it must be the thermostat ?
Fitting the new one tomorrow and hoping it fixes the problem !
The needle does rise but NEVER goes past the 50 mark ?


----------



## Stevie Jinx

You tube video is VERY cool mate.
*MANY* thanks


----------



## John-H

This should be useful:

Engine Coolant Temperature (ECT) Sensor -G2-/-G62- multi-pin connector
assignments









1 - ECT signal to temperature gauge
2 - Ground (GND) ( - )
3 - ECT signal to Engine Control Module (ECM) -J220-
4 - Sensor Ground (GND) ( - )

Coolant temperature 90 °C : approx. 110 Ohm
Coolant temperature 120 °C : approx. 50 Ohm

Basically, if you connect a 110 Ohm resistor between pin 1 and 2 GND the needle should go to 90 °C if the wiring loom and dashpod are Ok. <50 Ohms and the needle should read >120 °C


----------



## Stevie Jinx

Very useful John.
Cheers buddy.

Hoping the new stat will cure all the grief, will of course post my results


----------



## Stevie Jinx

*A HUGE THANK YOU*
to both Hoggy and John H.
GUYS.....*Thank you indeed for all your help and advice*. 

I fitted the new thermostat today after fitting the new water temp sensor, flushed the old coolant out with distilled water and topped up with the fresh stuff and look  
After a few miles this temp reading showed up...so happy  
I think a fair bit of the problem was the thermostat ! Seems to be all good now though. *Thank you once again guys.*
*THE OLD TEMP SENSOR AND THERMOSTAT*.

*NEW GAUGE READINGS.*


*OLD AND NEW THERMOSTAT.*


----------



## Bbuk

I've just changed my thermostat as the temperature was rising and not coming down 
The thermostat was not opening and the bottom hose never gets warm. 
It was straight forward but u had to disconnect the wire from the alternator along with the clamp 
And that gave me easier access to the bottom bolt
While I was there I checked the water pump and it was still on tight , not broken or come off
Dipstick comes off easy and no reason for it to broke 
After fitting I ran it up to temperatures the hose at the bottom was getting warm
Temperature fluctuated between 92-95. If I revved it it would go down and if I put the e con on the temperature drops rapidly


----------



## Stevie Jinx

Yea the alternator wire is in close contact with the socket when working at it, i managed to fit mine underneath with a bit of jiggling though.
Didn't break the dipstick as i cable tied it up out of the way without stretching it at all.
I think the aircon does have an effect on things though, strains it more i think and uses a tad more fuel too.
Bottom bolt is a pain though on the stat housing, hard to get off, *worse to refit* [smiley=bigcry.gif] dropped my screw into the engine bay but managed to get it 1st time with a magnetic arm.
Im off to get my diving gear collected tomorrow at the coast so i am gona take the TT with me for the run. It's a good 50 mile trip all in so any probs should show up as i only took it a few miles today.
Looks good so far though.


----------



## Stevie Jinx

Did the trip to the coast today and pushed the TT in places to make sure all was ok.
This was the max temp i reached  
*VICTORY*


----------



## Hoggy

Hi Stevie, TT & temp Looking good. 8) 
Hoggy.


----------



## Stevie Jinx

Hoggy said:


> Hi Stevie, TT & temp Looking good. 8)
> Hoggy.


Hi Hoggy.
Seems to be all sorted now mate. *Many thanks once again*


----------



## John-H

Well done


----------



## Stevie Jinx

John-H said:


> Well done


Cheers John.
Due as i said to some great help and advice from you guys.
Many thanks indeed.


----------



## jiver

just starting out on this.
thanks for the write up.

have pulled a few things off, and decided I need a few more tools to get to that bottom bolt :x

anyhoo, a couple of Q's:
*how much coolant should drain from the tap?*
I got the impression from the write-up, maybe 5 litres, but I got maybe 2.5 litres tops.

I haven't loosened this hose:








as recommended, is that loosened as in drain coolant from it? or loosen to allow some air intake to let more coolant flow from the tap?

EDIT: just thought I would mention the front is up on ramps, maybe that affects how much coolant drains?

also,
getting to that bottom bolt is going to be difficult, especially putting it back
I have undone the alternator connection and a wiring plug (blue arrows)
but am wondering if that wiring cable is attached to the alternator underneath somehow (red arrow) *Can't see how to unattach that? *Feels like a small nut underneath?


----------



## John-H

I can't remember exactly what the workshop manual said about loosening the oil cooler pipes - I think it just says to fully drain undo the connection. When I came to do mine it was awkward and tight so I left it coupled rather than risk damage. I'm not sure if it lets air in or drains out from that point. I put up with losing some coolant.

Some people undo the main battery connection to the alternator but that can be a shorting hazard unless you disconnect the battery and then you need to reset the windows and do the radio code. I left that too and instead persevered with the bottom bolt. It's a pig but with a small ring spanner and an Allen key you can manage. A small socket set and universal joint and wobble extensions may come in handy too.


----------



## newrayTT

There is a clip holding the wiring in place. I think it's a 10mm nut if I remember rightly. Bit difficult to get to but if you undo this and move the cable and main electrical feed out of the way it makes reaching that bottom nut a lot easier. I struggled for over an hour before removing the alternator connections but once I'd done that it was certainly easier. I used a small universal joint to reach the bottom nut, again patience is needed but eventually you will get there.
Didn't disconnect the battery but placed a bit of hose pipe over the main connector to prevent it shorting out.


----------



## jiver

thanks folks,



newrayTT said:


> There is a clip holding the wiring in place. I think it's a 10mm nut if I remember rightly. Bit difficult to get to but if you undo this and move the cable ....


yep, that's what it feels like; can't see it tho. Would be nice to get it undone tho.

been to the shops and bought a small universal for the small 10mm socket, so will see how that goes with extensions.



John-H said:


> can't remember exactly what the workshop manual said about loosening the oil cooler pipes - I think it just says to fully drain undo the connection...


yep. that's what the Bentley's says. just drain it. 5 litres.
Must be because I am on ramps?


----------



## newrayTT

I was up on ramps and just drained from the radiator drain plug, probably got about 4l out but did not lose any more when removing the thermostat housing. Don't really see a need to undo any hoses.


----------



## jiver

okay been there done that.
only had a little spill from thermostat housing so can't see the point of undoing any more pipe work
have to assume I only got about 3 litres of coolant due to being on ramps.
*
Recommend disconnecting the alternator wiring.*
I couldn't quite see how to do it until I got the pipe off. But it certainly made it easier putting that bottom bolt back in.

There is a clamp on the alternator wiring secured by a 8mm nut on a stud under the wiring harness, you can feel it if not see it.










So - disconnect battery. Unplug alt wiring connector. Take of the rubber cap and undo the wiring nut, and undo the 8mm nut on the clamp.

My wiring is different under the plate in front of the manifold, compared to the write up.
No wiring attached to the plate, except for the tube attached on the driver's side.
My wiring was clamped to the dipstick tube.
For my model (2002 BAM) *you have to remove and replace the plate with the dipstick tube attached*.
There is no way the plate will slip under the wiring connector and slot into an in place dipstick tube.
My tube was busted anyway (which is why the thermostat replacement got scheduled), so didn't realise all this until putting it back together.



















Thermostat all good now for some warmer (down-under) winter running.


----------



## RSSTT

Hi guys,

I believe I have a sticky thermo. 49C test and needle are reading the same.

The garage said it's nothing I should worry about. The car runs fine, and the needle tends to sit at 75. However i've been driving the car, and then stop for a short time and re-start, the needle tends to jump up to standard running temp - smack bag in the middle of the dial.

Having read the first couple of pages of this thread it appears that the thermo not operating properly can have an impact on the running of the car.

So should I be rushing to get the thermo replaced, or will it be fine?!


----------



## Hoggy

Hi, Temperature will always rise after switching Hot engine off because of the heat sink effect & no flows.
Engine will run rich if running too cool, not good for the engine or wallet long term.
Hoggy.


----------



## jiver

RSSTT said:


> ...
> 
> Having read the first couple of pages of this thread it appears that the thermo not operating properly can have an impact on the running of the car.
> 
> So should I be rushing to get the thermo replaced, or will it be fine?!


*I would do it. *
I left mine over the summer (Perth 35degC - 40degC daytime), so sometimes temp gauge said 90deg but sometimes lower.
In winter it was reading around 75deg at best, so planned to do it before this winter.

replaced thermostat and immediately noticed much smoother running. 
current daytime temp was around 28degC, so normally would be running around 80deg with thermostat stuck open.
now running at 90degC, and as said, much smoother running.


----------



## RSSTT

jiver said:


> RSSTT said:
> 
> 
> 
> ...
> 
> Having read the first couple of pages of this thread it appears that the thermo not operating properly can have an impact on the running of the car.
> 
> So should I be rushing to get the thermo replaced, or will it be fine?!
> 
> 
> 
> *I would do it. *
> I left mine over the summer (Perth 35degC - 40degC daytime), so sometimes temp gauge said 90deg but sometimes lower.
> In winter it was reading around 75deg at best, so planned to do it before this winter.
> 
> replaced thermostat and immediately noticed much smoother running.
> current daytime temp was around 28degC, so normally would be running around 80deg with thermostat stuck open.
> now running at 90degC, and as said, much smoother running.
Click to expand...

Will add this to the ever growing list of things I need to get done to the car :lol:


----------



## warrenstuart

I did this job today and big thanks go out to John-H and everyone else who's contributed... brilliant 

BUT... i have a leak from the lower part of the thermostat housing where it meets the block [smiley=bigcry.gif]

I've followed this guide to the tee inc the recommendations that others have posted from their experiences and the bloody thing is leaking.
So it's off to Halesowen Audi in the morning to order another O ring and a dipstick tube. I didn't break the tube but it doesn't half get in the way so it's coming off and a nice new shiney one is going back in it's place.
Any thoughts from anyone who's done this and had it leak would gratefully be received [smiley=thumbsup.gif]

Also the car is a 52 plate 2003 year model with a BAM engine. When i ordered the new stat i expected the guy at the parts dept to say i needed a "B" suffix stat from looking on their system which he did. When i took it apart it had a "C" stat fitted and i'm certain it's never been replaced because of all the paperwork and receipts i have going right back to purchase and inc every tiny thing even down to new key remote batteries so i'm sure a bill for a thermostat replacement would of been there.
So hey-ho it has an 80deg stat now like it or not :?

Warren.


----------



## John Stratton

Hi Warren ,
From memory doing mine I think the o ring could slip out of position and get nipped by the housing rather than staying in its seated position . I remember being concerned when I did mine due the angle you are working at when refitting . Hopefully it's just this that has happened and a new o ring will sort it . I think you will see once you get it removed again . 
I know not very helpful for you but sure you will get it sorted .
I assume the housing looked ok on removal .
Cheers
John


----------



## warrenstuart

Hi John

I'm hoping that what you've suggested is what has happened as it is very awkward to put the housing back on so fingers crossed.
The housing looked fine when it was off.
At least now i've done the job once i should have it done in half the time when i have another look tomorrow or Tuesday.

Hope you're well?

Warren.


----------



## John-H

Hi Warren,

As said, check the o-ring. The tube flange can become distorted with time and not sit flat and it can also develop hair line cracks which are very difficult to see. It might be fine but a replacement is not expensive. Make sure the block face is clean and free of debris too.


----------



## John Stratton

Hi Warren , yes I am fine thanks , I just wish we could get some better weather !!!

You are right , it will be easier the second time and you know what to expect and how best to get at that bottom bolt, I did not remove the alternator plug myself but I have seen it mentioned on here that it makes access a little easier . I think if I ever have to do mine again I would also purchase a new housing.
Anyway will be nice to hear what the problem was when get it completed .
Cheers 
John


----------



## warrenstuart

Hi John-H & John S

Well the update is that i took it apart again yesterday and really couldn't see any reason as to why it was leaking, the O ring looked fine and not pinched, distorted or flat-spotted through not getting the housing on correctly the first time and it all looked nice and clean.
Anyway another new O ring fitted that i purchased yesterday morning from Audi, all re-fitted and it seems dry so who knows??
Thing is i guess it only needed to be a tiny bit of grit etc and that's all it would take to cause a leak :?

The good thing is it only took about half an hour this time through knowing exactly what to expect and how to tackle the fiddly bits... experience is a wonderful thing!
Disconnecting the alternator wiring (after disconnecting the battery of course!) makes it so much easier to get to the bottom bolt and replacing the dipstick tube at the same time is a no-brainer i think because if you don't snap the old one removing it to make access easier you'll at least have a shiney new one and if you do break it you're not left without one 

Warren.


----------



## bobclive22

There is a clamp on the alternator wiring secured by a 8mm nut on a stud under the wiring harness, you can feel it if not see it.

*DO NOT STRUGGLE TO UNDO THAT NUT*, just pull the thick cable towards the rad, it will swivel in its clamp and the cable will end up under the clamp with the 8mm nut on top, you will now have clear access to the bottom bolt, NO NEED TO DISCONNECT LOOM.


----------



## nedge2k

Tip for anyone doing this...

It sounds drastic but just remove the alternator - makes life so much easier.

15mm spanner and a sturdy drill bit are all you need to get the belt free. Two bolts hold the alternator on, easily accessible. Then a big flat screwdriver to pry the alternator off then pull forward for lots of lovely clearance - don't even have to disconnect wiring.

Refitting the alternator is made a LOT easier if you put a 19mm socket over the metal inserts on the outside of the alternator mounts and then run a bolt through the pull the inserts out slightly - then the alternator will just slip on (instead of you having to wedge it back on and spend ages getting the bolt holes to line up). You'll spend way more time trying to get that bottom stat housing bolt than you need to otherwise and this way, you can ensure it all goes back together nicely and leak free 

Oh and as i'm sure has been mentioned a million times, buy a dipstick tube first. Mine broke as soon as I looked at it!


----------



## alun

that is a bit drastic. ive done a few thermostats now and i certainly wouldnt do that, its easy enough to reach around it. 
but each to there own.


----------



## JJBTT

Well it's my turn to ask the question, I've read through this thread, and several others with regards the discrepancy between 49c and dash pod - on mine - 
Dash pod rises to 80-90 after 10 mins or so driving, 49c shows rarely higher than 65, except after long traffic jams, where I've seen 90 on 49c but 110 ish on the gauge. 
I'm suspecting thermostat and sensor? 
Have had the eml a couple of times for Coolant temp too

(Have got both from Audi along with dip tube) - incidentally they have quoted £204 to do the job excluding parts!! 
Needless to say I'm gonna have a crack at it myself at that price!


----------



## Hoggy

Hi JJBTT, You appear to have a dash pod prob as well & gauge is reading high.
Dashpod should read 90 when actual coolant temp Code 49 is anywhere between 82 & 100 ish.
Code 49 feed dash gauge so 90 on Code 49 should show 90 on dash pod gauge, not 110.
Hoggy


----------



## JJBTT

Hoggy said:


> Hi JJBTT, You appear to have a dash pod prob as well & gauge is reading high.
> Dashpod should read 90 when actual coolant temp Code 49 is anywhere between 82 & 100 ish.
> Code 49 feed dash gauge so 90 on Code 49 should show 90 on dash pod gauge, not 110.
> Hoggy


Oh happy joy joy, I was wondering whether the dash pod could be part of it too. The fuel gauge is duff too. 
On that basis do you reckon it's worth changing the sensor before the thermostat to check that the 49c is reading right? 
Cheers Hoggy - Again!!


----------



## Hoggy

Hi, From what you've said Stat has definately failed, temp rising from 65 ish to 90ish when stationary proves it.
Sensor appears O.K. as dash should read same as sensor even if sensor gives incorrect reading, but dashpod isn't.
Hoggy.


----------



## JJBTT

Hoggy said:


> Hi, From what you've said Stat has definately failed, temp rising from 65 ish to 90ish when stationary proves it.
> Sensor appears O.K. as dash should read same as sensor even if sensor gives incorrect reading, but dashpod isn't.
> Hoggy.


Cheers Hoggy, will change it out then.


----------



## actu_8

nedge2k said:


> Tip for anyone doing this...
> 
> It sounds drastic but just remove the alternator - makes life so much easier.
> 
> 15mm spanner and a sturdy drill bit are all you need to get the belt free. Two bolts hold the alternator on, easily accessible. Then a big flat screwdriver to pry the alternator off then pull forward for lots of lovely clearance - don't even have to disconnect wiring.
> 
> Refitting the alternator is made a LOT easier if you put a 19mm socket over the metal inserts on the outside of the alternator mounts and then run a bolt through the pull the inserts out slightly - then the alternator will just slip on (instead of you having to wedge it back on and spend ages getting the bolt holes to line up). You'll spend way more time trying to get that bottom stat housing bolt than you need to otherwise and this way, you can ensure it all goes back together nicely and leak free
> 
> Oh and as i'm sure has been mentioned a million times, buy a dipstick tube first. Mine broke as soon as I looked at it!


Had mine done today and this method was used. I Diagnosed a faulty thermostat using this guide, got an OEM one from VW and an experienced mechanic (who had never done the job before) took just over the hour, including a few minutes to think through the approach. He removed the Alternator, tensioner and the throttle assembly and getting at the thermostat was extremely straightforward. I watched it from start to finish and it seemed the only dodgy bit was refitting the alternator belt on the pulleys correctly, he spent a few minutes thinking that bit through. Positives are that you don't need to drain (you lose a bit of coolant when the thermostat comes ouT), use a ramp or take off the bottom cover.

TT now running dead on 90c and a bit smoother.


----------



## maltloaf

I've read this how to a few times and I'm not actually sure if my stat is faulty or not ?

My temperature seems to take a good 15 mins to rise to anything like 80 and then whilst driving it never reaches 90. If I leave the car idling, it will reach 90/91 but if I drive again, it falls back into the 80-85 range. Am I right in thinking my stat is probably stuck open ? Thank you

malty


----------



## John-H

Sounds likely. You could be more certain if you used a thermometer in the coolant to rule out the sensor being out but if it takes a long time to rise it's usually a sign of being stuck open.


----------



## Hoggy

maltloaf said:


> I've read this how to a few times and I'm not actually sure if my stat is faulty or not ?
> 
> My temperature seems to take a good 15 mins to rise to anything like 80 and then whilst driving it never reaches 90. If I leave the car idling, it will reach 90/91 but if I drive again, it falls back into the 80-85 range. Am I right in thinking my stat is probably stuck open ? Thank you
> 
> malty


Hi, Temp rising to "normal" when stationary,& falling when moving is always a good sign of a failed stat. Always use OEM.
Hoggy.


----------



## maltloaf

Thanks guys, I'll get a stat and o ring ordered up.


----------



## maltloaf

Success here. All done in about an hour. Had to drill out the screws on the little plastic plate by the inlet as they were solid.

After all the horror stories of the bottom bolt it was actually very easy. I have a wobble bar set from when I did the sump on my golf and a couple or three of those together got in there without any problems at all. I took the alternator connections off and the p clip holding them to it.

Bought a spare dipstick tube and didn't need it, bought a spare coolant neck and didn't need it. Drained the coolant from the drain port on the corner of the rad and had almost none come out from behind the stat. I spilled more refilling it !

Temp got up to 90 before the top hose got warm so the stat is working and the fans cycled nicely on and off at around 98 degrees. Ran it up with the coolant lid off and then replaced it to get the system up to pressure and topped up as necessary. Had to add about half a litre if that.

Happy days. Thanks John for the thread and everyone else for the pointers.

Malty


----------



## John-H

Well done and speedy effort [smiley=thumbsup.gif]


----------



## evilClive

I eventually used a quarter inch wrench with knuckle and extensions, and it was easier (smaller and better access) than a half inch. But it took me 2 hours, including removing the undertray to get the bits that I dropped. Then half a litre of Coolant, run to temperature and clean up. Below average amount of swearing.


----------



## GerTT

Just thought I'd share my experience, may help others.

I had the low running temp, decided to do the stat and sensor together. After fitting both I was getting running temps of 99-105C on both 49C and dash. Initially I thought it may be the stat i fitted it was an 88c and I read after that some where 82c. I pulled the stat and tested it and it was fine. Turned out to be the sensor, even though it was new it was faulty, changed it and all good. The sensor has two outputs one goes to the ecu and the other goes to 49c and dash. I wasn't actually running too hot just false info from the stat. Never discount a new part being the problem just cause its new.


----------



## alexi7

Having just changed the thermostat on the 225 I have decided that maybe we should start a thread entitled " What Mr Audi designer thought up after he came back from the Pub" 7mm bolts, no one stocks those locally.


----------



## John-H

Wise words.


----------



## drone

I'll just chuck my 2p in here. On my 1st 225 coupe the thermostat retaining bolts appeared to have been tightened with a flogging hammer.
I actually bought an outlet so I could break the one in situ and get the bottom bolt more easily. However I looked at the installation and spent another £6 on a manifold gasket and took the inlet manifold off which is easy peasy. If your stat's past it then it's a pound to a pinch of pigs**t that the vacuum hoses are on their way out and two birds may be harvested for one stone.
After doing this job my £34 "water Diverter" from audi didn't work and of course I'd lost the receipt so another £34 but popped this one in a saucepan with water and brought it up to the boil yes it worked and no the first one didn't.
As it happened the original audi stat I took out had actually deformed and the bridge was twisted holding the stat about 0.5mm open on one side.
The reason I suspected the first replacement stat was defunct was the engine was at 100C and the stat outlet was cool to the touch, I was tempted to drill a 1mm hole in the flange of the stat to preclude any air locks but didn't bother in the end.
Thanks John for the write up and I hope you don't object to my addendum.


----------



## SC0TTRS

Another TT here suffering with a failed Thermostat.... :x

Phoned dealer to get a price, £31.68 for stat (water diverter :lol: ) 
O-Ring £3.43.

Prices shot up since John-H first posted :?

Didn't know Audi did local delivery, I could order over the phone and they would ship it to me for £6.00 if I wanted. 8)

Not sure if this has been answered before....but is it ok to drive about with a thermostat fully open like it is?...

btw appreciate the write ups John-H, very informative


----------



## John-H

Not for too long. If the thermostat is fully open the engine won't get up to temperature and will stay in cold running mode with a rich mixture, so lower mpg and potential bore wash over time.


----------



## bobclive22

I have said this before, No need to remove the alternator, no need to go under car, try this, pull hose off and let water go, follow first part of guide then undo the top connection of the thick cable on alternator, you will note that this cable is also connected to the bottom of the alternator with a clip, you will also note that the nut holding this clip is under the clip and you cannot get at it, to overcome this you grab the loose end of the cable and pull it hard towards the front of car, the cable and clip will rotate and reveal the hidden nut, the best part is that the rotated clip also gives clear access to the *problem nut *holding the stat cover, the rest is easy. I found this by chance.


----------



## miknix

Very nice write up, thank you. When getting stuck in traffic I always wondered if it was normal that the coolant temperature climbed to 100C until the fans kicking. Now I know it is.


----------



## John-H

miknix said:


> Very nice write up, thank you. When getting stuck in traffic I always wondered if it was normal that the coolant temperature climbed to 100C until the fans kicking. Now I know it is.


Thanks but not quite. I've improved the description around this issue now you mention it. The fans will cycle on and off in traffic with no airflow but there are two fan speeds low (~96°C) and high (~100°C). You will only likely notice the needle move upwards from 90°C if the high speed fan operation is called upon.


----------



## HemiCUDA1313

Thanks for this post. I was able to follow this and get it done without much trouble. Saved me a few hundred from the shop to do it myself.


----------



## yammo

John-H said:


> miknix said:
> 
> 
> 
> Very nice write up, thank you. When getting stuck in traffic I always wondered if it was normal that the coolant temperature climbed to 100C until the fans kicking. Now I know it is.
> 
> 
> 
> Thanks but not quite. I've improved the description around this issue now you mention it. The fans will cycle on and off in traffic with no airflow but there are two fan speeds low (~96°C) and high (~100°C). You will only likely notice the needle move upwards from 90°C if the high speed fan operation is called upon.
Click to expand...

Hi Thanks for the excellent write up.
I have a 2002 180bhp and I'm having a temperature issue.
In traffic the dashpod needle and 49C temp indicate 100-103 oC, when driving on the motorway it does reduce but never to a steady 90!
On checking the fans they are both turning.
IS THIS NORMAL???

I just recently developed a coolant leak from the coolant flange and i was considering changing the thermostat while i was at it.
Temperature sensors seem to be fine because the dashpod, 49C temp and a kitchen thermometer all confirmed the coolant was at 110 when the leak occurred and the coolant was lost.

Any ideas what is causing the high temperature readings?

Thanks again
Eamonn


----------



## John-H

If you are sure about the temperature sensor, then it's not cooling properly.

As mentioned before there are two fan speeds. The low speed works all the time when the aircon is on - that's normal and creates some airflow which usually keeps the engine cool when the car is stationary. There's a thermostatic switch for low speed that turns them on for when the aircon is off too. I think it's set to about 96°C but it won't be that accurate.

If the temperature reachs 104°C (aprox) then theres another thermostatic switch for high speed.

Driving on the motorway creates huge airflow so you don't need fans.

If your high speed is cutting in when idling and your low speed was operating up until then it shows that theres not enough coolant flow or air flow to take away the heat.

Most likely is a stuck thermostat or your impeller on the pump has fallen off or partially.

If you take the thermostat out you can feel the pump impeller through the hole. Turn the engine over to move it round but keep your finger out when doing so. Check it isn't loose on the shaft by trying to force it round with your finger.

If the impeller is fine hopefully the new thermostat will fix it. If that doesn't sort it you need to find another restriction like a collapsed hose or leaves blocking the radiator. If not then question your temperature sensor?


----------



## Hoggy

yammo said:


> John-H said:
> 
> 
> 
> 
> 
> miknix said:
> 
> 
> 
> Very nice write up, thank you. When getting stuck in traffic I always wondered if it was normal that the coolant temperature climbed to 100C until the fans kicking. Now I know it is.
> 
> 
> 
> Thanks but not quite. I've improved the description around this issue now you mention it. The fans will cycle on and off in traffic with no airflow but there are two fan speeds low (~96°C) and high (~100°C). You will only likely notice the needle move upwards from 90°C if the high speed fan operation is called upon.
> 
> Click to expand...
> 
> Hi Thanks for the excellent write up.
> I have a 2002 180bhp and I'm having a temperature issue.
> In traffic the dashpod needle and 49C temp indicate 100-103 oC, when driving on the motorway it does reduce but never to a steady 90!
> On checking the fans they are both turning.
> IS THIS NORMAL???
> 
> I just recently developed a coolant leak from the coolant flange and i was considering changing the thermostat while i was at it.
> Temperature sensors seem to be fine because the dashpod, 49C temp and a kitchen thermometer all confirmed the coolant was at 110 when the leak occurred and the coolant was lost.
> Any ideas what is causing the high temperature readings?
> Thanks againEamonn
Click to expand...

Hi, 110c ? are you sure, coolant will never reach 110 at atmospheric pressure.
Thermostat usually fails open causing low temps but could fail to open fully causing high temp.
Could be the pump but if you are sure the high temp reading are correct replace stat first & use an OEM 87 degree stat.
P/N 050121113C
Fans will always be running if A/C is on regardless of coolant temp.
Hoggy.


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## yammo

Hi
Thank you for the quick responses.
Car is booked in for new thermostat and coolant flange.
Hopefully this will sort out the current problems :wink: 
Eamonn


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## moa89

Maybe someone knows how to diagnose the problem I'm having. C 49 is showing absurd numbers on startup, car had been standing for over a day and temp at startup was 80+ degrees. And the coolant gauge is broken so can't check the truth with that either.
Just changed the coolant temp sensor for a new one, and from a generic obd reader shows the engine temp starting up 58C, engine was warm, to 68C in 10 mins or so. The question is is there an option to do a reset to the c 49 so I would know if it's telling me the truth. Or should I go and try to replace the thermostat to see if that might be the case.

Have not dropped the sump jet to see change the oil pickup tube to see if that might be causing the problems.


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## Hoggy

Hi, Did you use an OEM coolant temp sensor ? After-market are known to cause problems.
Code 49 is the actual coolant temp & should reach 90 within a couple of miles.If not change the stat.
If you change the stat use OEM 87 degree part No. 050121113C & get a dipstick tube as they usually get broken in the process.
Hoggy.


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## moa89

Thanks for the info, went for a drive and now shows the real temp. But still 76 degrees so a coolant flush and thermostat replacement it is.


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## John-H

49C is the direct sensor reading for the dash temp gauge, so strange readings worth one are likely to show up on the other.


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## moa89

Maybe someone smarter than me knows if the coolant hose coming of the thermostat should get hot?
Changed the thermostat and thought that I got all the air out but the coolant hose fro the thermostat does not get hot but all others do. I would not be a problem if the temp would stay normal, but the temp goes too hot. But seems to start of at the right point and not go too cold.

The reasons I have thought of are that the thermostat isn't working. Or I have cocked up the installation.
Air in the system still.
The problem is with the oil pick up line, someone mentioned it at some point, having similar overheating issues.
Or some other reason I don't know jet.


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## John-H

Have you got the thermostat the right way round? The spring side should be into the block so the coolant coming from the pump heats the wax within then it opens and lets hot coolant into the hose.


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## moa89

Went in the right way around. I thought there might be some air still in the system.


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## Hoggy

moa89 said:


> Went in the right way around. I thought there might be some air still in the system.


Hi, As I asked earlier was it an OEM 87 degree stat or an aftermarket version ?
Hoggy.


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## moa89

An aftermarket one, but febi bilstein, I come from a bmw background where febi used to be good.
Where could i get my mits on a oem one? Any places online? Not familiar with the UK car stores jet.


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## Hoggy

moa89 said:


> An aftermarket one, but febi bilstein, I come from a bmw background where febi used to be good.
> Where could i get my mits on a oem one? Any places online? Not familiar with the UK car stores jet.


Hi, To be sure it's genuine only Audi Dealer or Trade Part Supplies (TPS) Not cheap, but normally don't have to replace twice.
Site Sponsor Crewe Audi may post one, if you contact them.
https://www.ttforum.co.uk/forum/viewforum.php?f=201
Hoggy.


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## hutters

Thanks to everyone on this thread - tackled this today and (fingers crossed) seem to have been successful.

Couldn't have done it without this thread, a comprehensive socket set - particularly the universal joint- and a 5mm ball end allen key to get that bottom bolt started.

I bought this car 'cause I had so much fun with the Mk1 I bought back in 2002 and to be a project for me - to get out of my comfort zone and learn some new skills (I sit at a desk on a computer all day in my day job).

Two questions: I have this sensor below the intake manifold which I didn't see on other photos - 1) what is it and 2) how do the connectors detach (seems to be a standard type of connector across the engine)?


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## silverbug

hutters said:


> Thanks to everyone on this thread - tackled this today and (fingers crossed) seem to have been successful.
> 
> Couldn't have done it without this thread, a comprehensive socket set - particularly the universal joint- and a 5mm ball end allen key to get that bottom bolt started.
> 
> I bought this car 'cause I had so much fun with the Mk1 I bought back in 2002 and to be a project for me - to get out of my comfort zone and learn some new skills (I sit at a desk on a computer all day in my day job).
> 
> Two questions: I have this sensor below the intake manifold which I didn't see on other photos - 1) what is it and 2) how do the connectors detach (seems to be a standard type of connector across the engine)?


Not sure what the sensor is :lol: , but this describes the procedure for the connectors nicely ....






I also wince when I see videos of people removing those connectors with screwdrivers etc  .


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## hutters

silverbug said:


> Not sure what the sensor is :lol: , but this describes the procedure for the connectors nicely ....
> 
> 
> 
> 
> 
> 
> I also wince when I see videos of people removing those connectors with screwdrivers etc  .


I was close to using a screwdriver to remove it , but ended up leaving it in situ and working round it.

Thanks for the Youtube link, very useful


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## silverbug

hutters said:


> I was close to using a screwdriver to remove it , but ended up leaving it in situ and working round it.
> 
> Thanks for the Youtube link, very useful


Glad to help :wink:


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## Essex2Visuvesi

Thats the EGT Sensor module


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## SinfulDesignCom

Just my 10 cents worth on this. Can't believe I have been an owner for 8 years and never had to change the thermostat. Definately a +1 for OEM parts.

So.. regarding the dreaded bottom screw, I too found that John's tip of a ring spanner cracked the nut loose, but you cannot get any leverage to undo it further, but *you can easily get a 5.5 allen key in there and get a 90 degree sweep* at a time. Takes about 3-4 mins to undo this way, but beats moving all the other stuff.

But I joined the "dropped the bolt" club when refitting. But where do these things go?!? Whenever I drop a nut or bolt into the engine bay, that is it!! It goes to some engine bay netherworld never to be found again.


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## Hoggy

Hi, 19 + years & still original OEM 87 degree stat, but as you all know doesn't get much use.  
Hoggy.


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## SinfulDesignCom

I think 160k on the original clutch is one for the record books, which takes regular "a road" thrashes and a couple of track days a year.

But word to the wise, I bought a Gates thermostat and it stuck half closed!

OEM all the way.


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## Jburkemk1

Hi having a strang problem where my 49c is reading 90-100 when driving which seems normal from what I've read but when I stop it 49c get around 100 and stays but the dash pod pings to around 100-110, I've never seen my 49c get above 102. Not long bought the car so was just planning or replacing cooling temp sensor thermostat and flushing the coolant. Is there anything else I should look for? Hard to tell if it's just faulty dash pod or what


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## SinfulDesignCom

Jburkemk1 said:


> Hi having a strang problem where my 49c is reading 90-100 when driving which seems normal from what I've read but when I stop it 49c get around 100 and stays but the dash pod pings to around 100-110, I've never seen my 49c get above 102. Not long bought the car so was just planning or replacing cooling temp sensor thermostat and flushing the coolant. Is there anything else I should look for? Hard to tell if it's just faulty dash pod or what


That "ping" you speak about it normal. The water temp stays at 90deg on the dial and does not budge until you get close to the red, then it will jump. The 49c should be accurate, but I'd check to make sure your fans are cutting in first. Then make sure the temp drops on the display. The smaller dials have been known to be out, but if you are reaching 100deg too quick and it doesn't move when the fans cut in, then you need to be looking at blockages in the rad, water pump, operation of thermostat (might be only part open) etc...


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## Jburkemk1

SinfulDesignCom said:


> Jburkemk1 said:
> 
> 
> 
> Hi having a strang problem where my 49c is reading 90-100 when driving which seems normal from what I've read but when I stop it 49c get around 100 and stays but the dash pod pings to around 100-110, I've never seen my 49c get above 102. Not long bought the car so was just planning or replacing cooling temp sensor thermostat and flushing the coolant. Is there anything else I should look for? Hard to tell if it's just faulty dash pod or what
> 
> 
> 
> That "ping" you speak about it normal. The water temp stays at 90deg on the dial and does not budge until you get close to the red, then it will jump. The 49c should be accurate, but I'd check to make sure your fans are cutting in first. Then make sure the temp drops on the display. The smaller dials have been known to be out, but if you are reaching 100deg too quick and it doesn't move when the fans cut in, then you need to be looking at blockages in the rad, water pump, operation of thermostat (might be only part open) etc...
Click to expand...

Once the 49c drops back below 100 the dashpod will go back to 90 this only happens after I stop should both fans be cutting in at 100? And the regular driving temp is around 95-98 will only occasionally get to 100 and doesn't stay there long is this normal?

Thanks for your help


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## John-H

When stationary, with no radiator airflow, the engine temperature will normally climb until the radiator fans both cut in at ~96°C at low speed (this same low speed is on all the time if you have the aircon turned on). If the engine temperature continues to rise the fans will both switch to high speed at ~100° C which will bring the temperature back down.

If your thermostat switch switches a bit high, say 103° C, you might see the needle momentarily rise from 90° C. It's software weighted to indicate 90° C when the coolant temperature is between 80° C and 100° C.

Normally the low speed will give enough airflow to stop the temperature rising, depending on conditions like ambient temperature or if you've just stopped from high speed, and presuming your low speed fans are functioning. If your low speed fans are not working the temperature will cycle up to 100° C and down again repeatedly without airflow.


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## Jburkemk1

I am yet to see my smaller fan spinning I have checked the fans while air on on and only the large one spins, but from what I'm reading they should both be on together. Potentially a fan control module? I shall try check the fans at high temp tomorrow


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## John-H

They are wired in parallel so more likely one fan's internal dropper resistor has failed.


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## Jburkemk1

Many thanks!! The info I was rwding was not v clear. Shall investigate the fans asap


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## Jburkemk1

Hi I have got the car up to temp when for a drive and that got back and the temp on 49C was about 98 wnd only passenger larger fan was spinning. What could be the symptoms of this? Before I just order a new fan.

Many thanks


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## John-H

Did you monitor 49C whilst you were driving along? The graph I made in the how to, plotting temperature against a journey, shows both old and a new thermostat moving between 90° C and 100° C frequently. It tends to go up when you slow down or stop from high speed as the heat takes time to travel from the metal into the coolant and the thermostat will always lag a bit before opening - so going to 98° C when you stop is not unusual. A new thermostat gives better regulation. Both fans should spin though. With only one spinning it will take longer to cool and may venture into high speed of it exceeds 100° C.


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## Jburkemk1

Hi yes I have monitored it while driving and seems to be on par with your graph which gave me peace of mind. The only weird thing was the dash pod going to about 110ish after stop even if 49c is hasn't gone over 100. But going to replace the temp sensor for oem as it's an easy job and get a new fan as the smaller fan doesn't spin with the large one

Thanks for your reply


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