# Normal running temp for a 225 TT?



## SpencerD (Oct 21, 2011)

Hi,

Just wondered what is considered to be the normal (as read by CC 49C) engine coolant running temp for a 225 TT?

By normal I mean, running in free air - i.e. motorway and then in normal traffic, I appreciate there is likely to be a difference between the two temps but what do you normally see?

Cheers


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## jamman (May 6, 2002)

80-92 ish (I think)


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## SpencerD (Oct 21, 2011)

Cheers

Lower than I expected but I will keep my eye on it


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## jamman (May 6, 2002)

What are you getting Spence if you are running high you cant pretty much bank on that your thermostat is acting up.

Think it's meant to work around 82


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## Hoggy (May 8, 2002)

Hi, If its got an 87 degree thermostat it will run higher & be normal. 
Stationary & in traffic without aircon on, will reach 100 ish until fans cut-in, if aircon on, temp increase will be less as fan will already be running. 
Hoggy.


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## AmpTThill (Sep 18, 2011)

What do you mean 87 degree thermostat hoggy? Are their different types?


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## Hoggy (May 8, 2002)

AmpTThill said:


> What do you mean 87 degree thermostat hoggy? Are their different types?


Hi, Yes, Before 2003 it was 87 & after 2003, 82 degrees, unless doing regular track days etc, with our "cool" UK climate I can't see why all Mk1 can't use an 87 degree thermostat..
Hoggy.


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## SpencerD (Oct 21, 2011)

Jamman,

Last week I was getting 78 - 83 degrees (CC 49C) during say a 60 - 65 mph motorway drive, with what I have to assume was an 82 degree thermostat which was partially open all of the time, this would cause the DIS temp display to flit between 75 and 90.

I had the cam belt etc... Inc new metal impeller water pump and a new thermostat, I spoke to Midland VW and they said they always use 87 degree thermostats irrespective (whether that is based on a deliberate choice or just unaware of the change to 82 degree after '03 I don't know?)

The car now runs at 95 - 98 degrees on the same motorway drive and I expected it to get above 100 in traffic based on this but so far I have seen no more than 98 degrees (CC 49C) I will see if this is still true when I have done a little more driving in traffic.

Strangely having done quite a few VCDS data logs now and watching the water temp live in VCDS it is always 1 - 2 degrees lower than the CC 49C temp, such that the plotted data logs suggest a running temp of 93 -96 degrees

Possibly the difference between the two thermistor outputs from the coolant temp sensor?

Cheers


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## horneteer (Oct 21, 2008)

I have experienced something similar. The temperature gauge on my remapped 180 started intermittently dropping below the 90 mark. In my case the temperature sender was faulty but I had both the temperature sender and thermostat replaced. The car now runs at 94 to 98 degrees. I also have a new metal impeller water pump.

I have some thoughts on why my car and possibly also yours appears to run a little hot. One is that the new thermostat may not be opening up fully, either because it is new and it needs to bed in or because it is faulty. I recall reading here a similar story about a car running a few degrees above 90 when the thermostat was new.

The other more worrying possibility could be that the thermostat is functioning properly but not enough oil is being circulated through the engine due to a partially blocked strainer. Mine has covered about 90k miles and I am not aware of the strainer ever having been cleaned or changed.

I would think that in your case, since the thermostat appears to have been the cause of cooler temperatures, the thermostat is capable of lowering the temperature below 90. So possibly your new thermostat is not opening fully, for whatever reason.

Hope this helps

Cheers
H


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## Hoggy (May 8, 2002)

Hi, If an 87 degree thermostat is fitted, then it does not start to open until 87, so will always run at a higher temp than an 82, which will start to open at 82.. 
Hoggy.


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## SpencerD (Oct 21, 2011)

This shows two logs of coolant temperature on the same motorway journey

Ambient temp was a couple of degrees different between the two days










Hi Hoggy, yes I understand an 87 thermostat will runner hotter than an 82 degree, just trying to see what coolant temp anyone else sees in normal use.

So far in fairly light traffic the temperature regulation seems very good as it hasn't gone more than say a degree more than the temp seen on the motorway, around 87 degrees

Cheers


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## t0bie (Jun 14, 2012)

Am i Getting from this that the normal operating temp is between 80-90?
When im pootering around the town it usualy indicates 70 and only when I thrash it does it jump into 90 and just sits there untill I cool off


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## kazinak (Mar 23, 2010)

My needle always sits at 90 , in the town or on the track no difference, if yours is jumping around that means your thermostat is faulty

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## Hoggy (May 8, 2002)

Hi t0bie, Should reach 90ish on 49c & dash within 3 miles ish. & stay there, may rise after a blast & stationary in traffic for long periods, but less noticable if aircon on as fan will be running. 
Gauge is dash weighted to read 90 when 49c is anywhere between 82 & 98 ish, fans usually cut-in around 103ish.
Hoggy.


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## Skeee (Jun 9, 2009)

kazinak said:


> My needle always sits at 90 ..........................


Mine's similar. The needle's almost always 'fixed' at 90, on motorway and around town & country roads.
Around town 49C shows around 90 and sometimes down to 85 on a country road low rev run on a cool day. 
Needle always shows 90 except when 49c shows 83-85 the needle will drop a tiny bit.

It's an 05 225 roadster so is it an 82 stat?


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## Hoggy (May 8, 2002)

Skeee said:


> It's an 05 225 roadster so is it an 82 stat?


Hi, Its possible or just opening abit early/closing abit late. 
Hoggy.


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## Cheekos (May 19, 2012)

Hoggy said:


> Skeee said:
> 
> 
> > It's an 05 225 roadster so is it an 82 stat?
> ...


hey, noticed my temp needle going over 90 degrees, about half way into the block,
Just done an engine temp test, shows 90 degrees, coolant temp 95, Is this normal?


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## Hoggy (May 8, 2002)

Cheekos said:


> Hoggy said:
> 
> 
> > Skeee said:
> ...


Hi, Code 49 should show 88/92 during normal motoring. Forget about using code 51 as it always settles at 90 regardless.
Code 49 is actual coolant temp & dash gauge is weighted to show 90 when Code 49 is anywhere between 82 & 100ish. 
Hoggy.


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## cimsa8 (Feb 5, 2015)

I have a 2002 Roadster 225 and actually I change water pump, auxiliary water pump, radiator, thermostat, and Thermo switch, but in the dash in Code 49 I see my car is excessive hot sometimes it gets 115-117 degrees, if I run in normal traffic the temperature is in 95-98, but not sure if this is normal or not.

Obviously I drain the water and change with G12, but the temperature continues so high.

There is someone who explain if this is normal and if not, how to repair or what else I need to see...

thanks in advance.


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## Hoggy (May 8, 2002)

Hi cimsa8, 115/117 if true, is much to high & fan should be running at those temps, check if it is.
Did you use an OEM coolant temp sensor, if not replace that first.
Normal running temp on Code 49 should be 88/93 ish. 
Hoggy.


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## cimsa8 (Feb 5, 2015)

that is correct, the fan apparently works fine, (I changed one of them both because it did not start in High temperature), I am not sure if is possible I need to purge some air or something. and here I don`t have other car for reference... just only you.

If the temperature continues high (more when I am going climbing a hill and I behind of a truck), what else I need to look, the last think I want to avoid is to break the motor for overheating.


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## Hoggy (May 8, 2002)

Hi cimsa8, As you have replaced every thing in the cooling system, did you use an OEM thermostat & coolant temp sensor.
If not that could be the problem. Replace coolant temp sensor first with OEM, as those high temp reading could be false. I would expect steam to be issuing from coolant reservoir vent at those temperatures.
Hoggy.


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## David PT (Mar 20, 2019)

** edit: I have no clue how I thought I'd read the whole thread before I posted only to see that I hadn't... and answers were there! Lol

Hate to resurrect old threads, but I've only had my TT (2002 25 Quattro vert') for about five months and it has always seemed to run hot. I've checked on the ClimaTronic panel and my coolant temperature gets over 100°C, just now when I pulled in my driveway after a 9 mile commute home from work got up to 107. Do I start with the thermostat? Or the sensor?. My oil level is good and my coolant level appears to be good as well.


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## Hoggy (May 8, 2002)

Hi, Depending on thermostat fitted, 87 degree stat, normal is 89/92. low speed fans should run by 98 & high speed by 106 ish.
Are you using actual coolant temps using *Code 49* on climate control? 




Are both fans running when A/Con ON?
Do both fan runs when temps are indicating high.
Replace coolant temp sensor first & use OEM..059919501A
Coolant temp will rise when stationary until fans cut-in to cool.
No need to resurrect old threads just check todays posts  
Hoggy.


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## FINDTT (Aug 9, 2020)

Lately I have been getting coolant temps up to 96 (needle going to next stop above 90) when cruising uphill at 110 km/h on the freeway. I hadn’t noticed this in the past, usually 88 to 92 (needle staying on the 90 in the deadband) all thetime except occasionally going as high as 98 when idling stopped in traffic. Seems to get up to 98 pretty quickly idling, more than I remembered it doing in the past anyway.
is it normal to get temps above 94 at freeway speeds or is my coolant pump possibly on the way to failing?


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## David C (Apr 15, 2013)

FINDTT said:


> Lately I have been getting coolant temps up to 96 (needle going to next stop above 90) when cruising uphill at 110 km/h on the freeway. I hadn’t noticed this in the past, usually 88 to 92 (needle staying on the 90 in the deadband) all thetime except occasionally going as high as 98 when idling stopped in traffic. Seems to get up to 98 pretty quickly idling, more than I remembered it doing in the past anyway.
> is it normal to get temps above 94 at freeway speeds or is my coolant pump possibly on the way to failing?


Check the electric coolant pump.
Turning the ignition on and off is enough to trigger it, no need to start the engine. It should run for 10 minutes after the ignition is turned off, but it also runs when the engine is running, pulling hot coolant from the turbo.

Also check the rad fans. Both should run constantly at low speed if your A/C is working.
If the A/C isn't working, they won't be triggered until 95degC rad temperature, which could be 98degC at the engine.

Remember fans wired as a pair, if you only see one running, the other one has failed.


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## grahamtt225bam (Aug 18, 2021)

I know these cars definitely prefer genuine thermostats when i baught my o3 tt with code 49 it was running 95-98 normal driving i baught a genuine thermostat now sits at 85-90 far better now more normal.


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## FINDTT (Aug 9, 2020)

Electric coolant pump runs when the ignition is turned on but I couldn’t hear it after stopping the engine. Weird. 
Both fans running with car idling. Idling on a warm day (about 25c ambient) Temperature goes up to about 100 then settles about 95 after fans come on. Fans did not go to high speed but I guess that is because the car did not get hot enough.
coolant temp sensor renewed about a year ago.
Some inconsistency noted between OBD, 51C and temp gauge noted.
I think the cooling system is working ok. Maybe dashpod playing up and temp gauge just reacting a bit differently than it used to?


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## Hoggy (May 8, 2002)

FINDTT said:


> Electric coolant pump runs when the ignition is turned on but I couldn’t hear it after stopping the engine. Weird.
> Both fans running with car idling. Idling on a warm day (about 25c ambient) Temperature goes up to about 100 then settles about 95 after fans come on. Fans did not go to high speed but I guess that is because the car did not get hot enough.
> coolant temp sensor renewed about a year ago.
> Some inconsistency noted between OBD, 51C and temp gauge noted.
> I think the cooling system is working ok. Maybe dashpod playing up and temp gauge just reacting a bit differently than it used to?


Hi, Do not use Code 51 it is not coolant temp & it always settles at 90 regardless. Code 49 is coolant temp but it can give false readings if dashpod is faulty.
Assuming coolant temp sensor is 100% the only accurate coolant temp is from the ECU using VagCom or similar.
Dash gauge is weighted to show 90 when coolant temp is anywhere between 82 & 98 ish
Hoggy.  .


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## fire88 (Jul 15, 2021)

Had a 30 minutes drive tonight, it's showing 105 and fan not automatic turned on 

It's summer here, so something is wrong with my fan. I have replaced the coolant fan relay, old one was crushed and rusty. 
Electric pump works, it didn't work before. 

I need check Relay and fuse, which seem OK. 
Then what else could be wrong. 
It's really fun car, one thing after another.


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## David C (Apr 15, 2013)

fire88 said:


> Had a 30 minutes drive tonight, it's showing 105 and fan not automatic turned on
> 
> It's summer here, so something is wrong with my fan. I have replaced the coolant fan relay, old one was crushed and rusty.
> Electric pump works, it didn't work before.
> ...


If the green 30A fuse and its socket hasn't melted, it is likely the resistors for the low speed fans in the fan motors have failed.
High speed fans are triggered at 102degC (rad temperature, not engine temperature) so likely you were almost at the point of triggering those.

Low speed fans for engine cooling don't use the Fan Control Module, they are purely triggered by the 1st stage of the 2-stage thermal switch on the rad.


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## fire88 (Jul 15, 2021)

David C said:


> If the green 30A fuse and its socket hasn't melted, it is likely the resistors for the low speed fans in the fan motors have failed.
> High speed fans are triggered at 102degC (rad temperature, not engine temperature) so likely you were almost at the point of triggering those.
> 
> Low speed fans for engine cooling don't use the Fan Control Module, they are purely triggered by the 1st stage of the 2-stage thermal switch on the rad.


Good to know. I will check it out. 

Thank you. 

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## fire88 (Jul 15, 2021)

Unplugged the two fans, tested with battery charger which is working OK. 

Replaced the fan relay box, now fans kick in when it reaches 98.









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## fire88 (Jul 15, 2021)

Lifted up with 4 Jack stands and driving at 3 gear, then I heard lots of clicks from left side of the engine bay, I thought it was from the transmission, then it was from abs pump kicking because of the difference of speed from 4 wheels. 

What a false alarm! 

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