# TT MK1 - temp gauge goes up when stood still - themostat??



## jairo1982 (Jul 3, 2010)

hello I have a MK1 Audi TT and the last few weeks the temp guage goes up to just under the red when your parked up and the engine is left running but as soon as im driving goes down to the middle again, I have had a few TTs and the temp gauge has always stayed on around the middle, just wondering if this is a dodgy themostat?? are the fans viscus fans as i cant hear the fan cutting in when the temp starts to creap up, any help would be great

thanks


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## peter-ss (Sep 3, 2008)

If you look up 49C on the forum it will tell you how to use your climate control unit to display coolant temperature.

The dashboard needle is weighted towards 90oC, so that it shows 90oC anywhere between 80oC and 100oC.

Below is a graph showing my coolant temperature with the engine up to running temperature and ticking over. You can see on mine that the temperature peaked at 104oC but was being controlled by the fan.


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## dpbayly (Mar 16, 2011)

I once worked on a Golf that had the same problem and it was the impeller on the water pump had come away from the shaft and on idle it would not be turning but when the engine speed was increased the impeller must have been moving just enough to circulate the water and bring the temp down.


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## Hoggy (May 8, 2002)

Hi jairo1982, More than likely rad fans not cutting in. Put air-con on fan should be running.Check fuses/links on top of battery if fans don't run as temp increases, but check 49c using climate control, may not be as hot as you think.
Click the link for climate control.









http://video.aol.com/video-detail/audi- ... /302016129
Hoggy.


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## V6RUL (May 28, 2009)

I think your stat is passing but the above checks should pin point where the issue is.
Steve


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## tony_rigby_uk (Nov 27, 2008)

sounds like it is the fans, very rare to have a thermpostat fail closed, usually they say open and car doesn't get to 90 and drops below 80 when driving... for a temp rise i'd say it would be fans... if they are firing up when it's hot then it'll have to be the pump not getting the water round the system.. could be too much water and not enough coolant also in hot weather... when was the last time the coolant was replaced? and is the correct ratio in?


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## Gazzer (Jun 12, 2010)

jairo1982 said:


> hello I have a MK1 Audi TT and the last few weeks the temp guage goes up to just under the red when your parked up and the engine is left running but as soon as im driving goes down to the middle again, I have had a few TTs and the temp gauge has always stayed on around the middle, just wondering if this is a dodgy themostat?? are the fans viscus fans as i cant hear the fan cutting in when the temp starts to creap up, any help would be great
> 
> thanks


answered your own question here i think, deffo fan not coming in


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## danger (Jun 20, 2008)

I have the same issue, will check my fans!


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## jairo1982 (Jul 3, 2010)

getting checked tmz


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## thewolf (Jun 20, 2010)

Hi,

I have a 2001 Audi TT 1.8T 180HP (AUQ engine).

After the car has warmed up, my temperature gauge reads 90C most of the time while driving.
When the actual temperature is between 80C and 100C on channel 49 on the climatronic, the gauge stands still on the 90C mark. Does your dashpod have the same "weighting" interval?

Recently, only when stuck in traffic or when stopping after a ride, sometimes the gauge will go over the 90C mark, with channel 49 actually reading over 100C (if I remember correctly up to 105C).

Recently I replaced the dashpod and the timing belt with the water pump, the thermostat valve was replaced about half and an year ago.

I don't remember the gauge going over 90C often in the past (when my previous dashpod still worked fine). Maybe I don't remember correctly and it's normal that the temperature goes over 100C sometimes? Or this looks like a little overheating? What could be causing it?

What is the normal operating temperature range for the 180HP engine?

Thanks.


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## Hoggy (May 8, 2002)

Hi the wolf, Temps can rise when stationary in traffic, until fans cut-in @ approx 102 degrees.
Hoggy.


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## thewolf (Jun 20, 2010)

Hoggy said:


> Hi the wolf, Temps can rise when stationary in traffic, until fans cut-in @ approx 102 degrees.
> Hoggy.


Does your gauge also move after the 90C mark sometimes?

My worry is that I don't remember moving it much in the past, it sometimes moves now when the car is not moving, the engine is running and the outside temperature is hot.


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## Hoggy (May 8, 2002)

Hi The wolf, Yes perfectly normal especially after a blast & then stuck in traffic. While moving the ram air effect through rad cools the engine, stationary, no air flow through rad until fans cut-in approx 102degrees. Temperature doesn't rise as much if air con is on because 1 fan is already running. Dash Pod gauge is weighted to read 90 any where between 80 & 95 ish.
Hoggy.


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## XXX-1.8T (Apr 25, 2008)

Guys sorry to bump up an old thread but my mate has just done water pump, temp sensor, fan switch and thermostat.

The needle still goes past 90 into 100 zone when sitting in traffic.

When he turns the AC on it goes back to 90 so what else could it be?

He has also desludged radiator and pipes.

Do you think its his dashpod?


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## Hoggy (May 8, 2002)

Hi, Fans cut-in approx 102 ish using Code 49c on Climate Control. Check temps on Code 49c & leave it a bit longer to see if fans cut-in. Use Code 49c coolant temp, not 51c engine temp.




Hoggy.


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## XXX-1.8T (Apr 25, 2008)

If fans dont cut in at 102c what does this mean? He has checked the fans and also changed the fan switch.

Once he starts moving temp goes back to 90c.

If he turns AC on temp goes back to 90c.


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## Hoggy (May 8, 2002)

Hi, Temp will rise when stationary, but fans should cut-in by 106 ish on Code 49c. If still not running at 106 ish, turn A/C on to reduce temp. Next check fan control module, it's underneath the battery, also check fuses on top of battery for corrosion/burning. 








Temp dropping when air con on, proves there is nothing wrong with coolant system, as such.
Hoggy.


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## XXX-1.8T (Apr 25, 2008)

Thanks Hoggy so you think its the dash pod then?


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## Hoggy (May 8, 2002)

XXX-1.8T said:


> Thanks Hoggy so you think its the dash pod then?


Hi, *No,* I never said that..... Fans are not running for some reason.
If the fans are still not running when temp gets to 106 ish, then check out the fan control module under battery & fuses on top of battery as in previous post. Check actual coolant temp using Code 49c on Climate Control.
Hoggy.


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## XXX-1.8T (Apr 25, 2008)

Hoggy said:


> XXX-1.8T said:
> 
> 
> > Thanks Hoggy so you think its the dash pod then?
> ...


ok thanks


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## Hoggy (May 8, 2002)

Hi, No the fan temp switch is in/on radiator, the module is different & beneath the battery/Tray.
There are also the connection/fuses on top of battery which can corrode & cause fan probs.
Hoggy.


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## XXX-1.8T (Apr 25, 2008)

Thanks ill let him know


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## Hoggy (May 8, 2002)

Hi, Not sure what that means, unless he means an 82 degree thermostat. Even if fans were running all the time, if thermostat is working correctly, coolant temperature would still be controlled by thermostat, not the fans.
Fan runs O.K. if aircon is on, fan switch has been replaced, so it has to be a prob with fan module/control system. 
That has to be sorted first. If the main prob isn't going to fixed, then just turn A/C on in traffic. :roll: :? 
Hoggy.


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## Wak (May 6, 2002)

XXX-1.8T said:


> Guys sorry to bump up an old thread but my mate has just done water pump, temp sensor, fan switch and thermostat.
> 
> The needle still goes past 90 into 100 zone when sitting in traffic.
> 
> ...


If ambient outside temp is over 5 degrees turn the A/C onto full auto.
- check the Fans are operating. both of them! - If not then the fans are likely to be broken but further testing of the fan controller output or A/c to prove they are not the cause is needed.

If the owner is driving with A/C on Econ on , then the behavior you describe is normal if the fan low speed is not driven until a 100 degree trigger.

As it is getting hotter its either a normal rise before the fans are having an effect or perhaps the high speed trigger is being reached.when it gets pulled back down

Try the A/C on test to prove the fans do work first.


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## Wak (May 6, 2002)

XXX-1.8T said:


> If fans dont cut in at 102c what does this mean? He has checked the fans and also changed the fan switch.
> 
> Once he starts moving temp goes back to 90c.
> 
> If he turns AC on temp goes back to 90c.


I'm getting confused because the above sounds like normal behavior.


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## Hoggy (May 8, 2002)

Wak said:


> XXX-1.8T said:
> 
> 
> > If fans dont cut in at 102c what does this mean? He has checked the fans and also changed the fan switch.
> ...


Hi Wak, Me as well. It appears the fans are not running even with coolant temp at 106, but fan runs when air con switched on & cools the coolant down. I Suggested fan control module checked out, as fans are not running when temp high. Rad temp switch has been replaced.
Hoggy.  :?


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## s140 (Apr 24, 2017)

Hi all...new to the forum! quick question my mk1 225 1.8 TT - had water pump changed recently due impellars going bust! all is fine now generally apart from on occassion when driving the coolant temp will rise close to the red zone and then bring itself down after a short distance, also sometimes it drops the other way to 76...even after driving for 30miles plus..again rises itself up to 90 eventually. the 49c trick seems consistent with the needle readings. finally the blowers are warmish with the central 2 not blowing anything out really. (they did before) any ideas??


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## Hoggy (May 8, 2002)

s140 said:


> Hi all...new to the forum! quick question my mk1 225 1.8 TT - had water pump changed recently due impellars going bust! all is fine now generally apart from on occassion when driving the coolant temp will rise close to the red zone and then bring itself down after a short distance, also sometimes it drops the other way to 76...even after driving for 30miles plus..again rises itself up to 90 eventually. the 49c trick seems consistent with the needle readings. finally the blowers are warmish with the central 2 not blowing anything out really. (they did before) any ideas??


Hi, It appears fans are cutting in to control coolant temp, so probably the thermostat is playing up, especially as temps are dropping to 76 ish. Replace using an 87 degree OEM thermostat.Part No. 050121113C
Hoggy.


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## s140 (Apr 24, 2017)

thanks hoggy stat ordered from audi to fit later this week. fans seem to be working fine. I know dodgy stats can cause underheating issues but would one also cause the slight overheating? could it be temp sensor? (ive got a green one fitted)


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## Hoggy (May 8, 2002)

s140 said:


> thanks hoggy stat ordered from audi to fit later this week. fans seem to be working fine. I know dodgy stats can cause underheating issues but would one also cause the slight overheating? could it be temp sensor? (ive got a green one fitted)


Hi, It's possible that thermostat is slow to open & slower to close, that could cause the intermittent high & low temps, so I suggest it's the stat.
Hoggy.


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## s140 (Apr 24, 2017)

thanks... new stat should be in place by friday so il see how that does!


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## s140 (Apr 24, 2017)

Hi just an update - problem seems to be all sorted now new audi thermostat fitted..all seems fine and heaters blowing strong! advice - stay from aftermarket stats, new one from audi cost £30 inc vat and fitted at a local mechanics for £20


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## Hoggy (May 8, 2002)

s140 said:


> Hi just an update - problem seems to be all sorted now new audi thermostat fitted..all seems fine and heaters blowing strong! advice - stay from aftermarket stats, new one from audi cost £30 inc vat and fitted at a local mechanics for £20


Hi, Excellent, pleased hear stat was correct diagnosis. £20  to fit that was a bargain. 8) 
Hoggy.


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