Overheating issue

[espo4442]

Trying to figure out if I have thermostat and /or water pump issue. Car is a 2010 S4 with 88k miles. Recently I noticed the fan kicking on after a short drive (30 degree weather) coolant temp didn't rise off middle, so I checked the coolant and saw it was a little bit below min so I added until max. Drove the car and noticed that now after about 20 min of driving at 60mph plus the coolant temp slowly climbs past middle . I obvious kick the heat full blast and temp returns to normal). Coolant temp increases normally to correct operating temp and stays there for some time with heat off until it eventually increases after some time. Thoughts? I'm used to failures causing temps to rise immediately..

[14S4GWM]

I would say it's the thermostat that the 10's are infamous for. Have you had it replaced before?

[DGVR6]

Happen to me not too long ago.. When you open the hood the fans blows ice cold air through the rad but hose is hot then its ur tstat or water pump .. Most likely the t stat.

The reservoir is also cold to the touch when it should be warm.

[schirm]

T-Stat happened to me couple months ago exact same symptoms and miles.

[espo4442]

I believe it had been replaced previously around 30k prior to me but I can't say for sure. Anyone have a good write up or estimated cost to replace?

[schirm]

I believe it had been replaced previously around 30k prior to me but I can't say for sure. Anyone have a good write up or estimated cost to replace?

There is some DIY around, but Audi charged me 1,200. So independent shop would probably do it for around 900?.

[infinkc]

i had did a writeup, but all the links are dead now since the thread is quite old. I need to see if i can find the pictures to re-host them.
http://www.audizine.com/forum/showth...king-time-bomb!

[amz]

is there a tstat for our cars that will fail open yet? I'd rather it fails open so it runs rough and takes a while to warm up, but at least I can keep driving.

[S4'ed]

No

[espo4442]

Any possibility it could be the water pump, tech logged the coolant and it maintained a steady temp. I'm thinking it might be a flow problem...

[audistealth]

Isn't there a single recall for the thermostat and two other things? Maybe last year?

[Hawkpilot6060]

Hey, I hope you figure out the issue and get it fixed easily. Not to thread jack, but guys, is there a way to test the fan operation? I swear I have never heard mine come on. I am wondering if there is a way to test it? Thanks for any help, sorry to thread jack. Rick

[S4'ed]

It is a flow problem....the thermostat isn't opening properly...!!!

[DGVR6]

Hey, I hope you figure out the issue and get it fixed easily. Not to thread jack, but guys, is there a way to test the fan operation? I swear I have never heard mine come on. I am wondering if there is a way to test it? Thanks for any help, sorry to thread jack. Rick

Vagcom
I believe under engine

[espo4442]

So help me understand this, the thermostat can read the correct temp but not be opening properly?

[audistealth]

So help me understand this, the thermostat can read the correct temp but not be opening properly?

Yep

[espo4442]

Thanks for the response guys.

[mkato13]

definitely sounds like the thermostat. I had same problem and I had a replaced by an independent repair guy and a colostomy $900. From what I understand its quite a lot of work to do because of Audi placed it under the intake manifold

[fitzydude]

Great timing on this thread!! The last couple nights I've noticed my fans have been coming too soon and staying on with outside temps around 40 degrees. My temp gauge isn't climbing past the middle yet, but tomorrow morning I've got to drive 13hrs which is terrible if my thermostat is failing. Today I'll pick up a thermostat from Audi, I'll bring my tools in case I need to replace the t-stat on the road. Do I need to drain all the coolant for this job or could I get away with partially draining the coolant??

[S4'ed]

This is not a typical thermostat replacement job : the supercharger needs to be removed to gain access to the thermostat. And even then, the thermostat housing is not easily removed. You don't need to dump all the coolant to do this job, but you must follow the factory service manual refill and bleed procedure to get the air out. (2 bleeder screws on the supercharger, one bleeder "port" at the heater core hose connection in the cowl area). A much better way to refill and bleed this system is a vacuum refill tool (ebay $60), but using that method requires you to dump all the coolant out first. Use ONLY the VW/Audi antifreeze and only mix with distilled water. While the whole mess is apart, it might be good to also replace the waterpump as a preventive measure. I would NOT want to do this repair "on the road", or risk overheating your aluminum block engine. If you need to take a roadtrip, a rental car at $37 a day is a much safer thing to do...then fix your Audi when you get back.

As a side note : the radiator fans suddenly running on high is a better warning that the thermostat is failing, rather than the engine coolant temperature gauge on the dash. The gauge is 'dumbed down", it does NOT accurately show the engine operating temperature when the needle is at the "normal" mid-point mark. The needle stays at the midpoint mark for actual coolant temperatures between 176F and about 240F......so by the time the needle moves above the center mark, the car is in a full overheating state.

[fitzydude]

This is not a typical thermostat replacement job : the supercharger needs to be removed to gain access to the thermostat. And even then, the thermostat housing is not easily removed. You don't need to dump all the coolant to do this job, but you must follow the factory service manual refill and bleed procedure to get the air out. (2 bleeder screws on the supercharger, one bleeder "port" at the heater core hose connection in the cowl area). A much better way to refill and bleed this system is a vacuum refill tool (ebay $60), but using that method requires you to dump all the coolant out first. Use ONLY the VW/Audi antifreeze and only mix with distilled water. While the whole mess is apart, it might be good to also replace the waterpump as a preventive measure. I would NOT want to do this repair "on the road", or risk overheating your aluminum block engine. If you need to take a roadtrip, a rental car at $37 a day is a much safer thing to do...then fix your Audi when you get back.

As a side note : the radiator fans suddenly running on high is a better warning that the thermostat is failing, rather than the engine coolant temperature gauge on the dash. The gauge is 'dumbed down", it does NOT accurately show the engine operating temperature when the needle is at the "normal" mid-point mark. The needle stays at the midpoint mark for actual coolant temperatures between 176F and about 230F......so by the time the needle moves above the center mark, the car is in a full overheating state.

Great information, printing it out now! Great info on the temp gauge too, I'll connect with the Torque app to monitor the coolant temp more closely just in case worse comes to worse. I figure it will be cold enough this weekend on my drive north that over heating won't be an issue on the interstate. Once I get to my destination I'll have a garage to work in if I do need to change the T-stat. Perhaps I'm just being a bit paranoid that the t-stat is failing but I'd like to be prepared if worse comes to worse. Thanks!

[espo4442]

This is not a typical thermostat replacement job : the supercharger needs to be removed to gain access to the thermostat. And even then, the thermostat housing is not easily removed. You don't need to dump all the coolant to do this job, but you must follow the factory service manual refill and bleed procedure to get the air out. (2 bleeder screws on the supercharger, one bleeder "port" at the heater core hose connection in the cowl area). A much better way to refill and bleed this system is a vacuum refill tool (ebay $60), but using that method requires you to dump all the coolant out first. Use ONLY the VW/Audi antifreeze and only mix with distilled water. While the whole mess is apart, it might be good to also replace the waterpump as a preventive measure. I would NOT want to do this repair "on the road", or risk overheating your aluminum block engine. If you need to take a roadtrip, a rental car at $37 a day is a much safer thing to do...then fix your Audi when you get back.

As a side note : the radiator fans suddenly running on high is a better warning that the thermostat is failing, rather than the engine coolant temperature gauge on the dash. The gauge is 'dumbed down", it does NOT accurately show the engine operating temperature when the needle is at the "normal" mid-point mark. The needle stays at the midpoint mark for actual coolant temperatures between 176F and about 230F......so by the time the needle moves above the center mark, the car is in a full overheating state.

Do you suggest replacing the water pump while I'm in there?

[S4'ed]

Yes....while you are in there...change the pump too.

[ATX_S4]

Isn't there a single recall for the thermostat and two other things? Maybe last year?

I'm pretty sure the fuel rail recall included replacement of the thermostat and PCV for certain models.

[audistealth]

I'm pretty sure the fuel rail recall included replacement of the thermostat and PCV for certain models.

Yes, that's the one. I couldn't remember that when I posted earlier.

[LeadToRome]

Is there a hack via vag-com or some other way to get the temp gauge to show actual engine temp? I know the lap timer will show oil temp, how about coolant temp?

[S4'ed]

I was wondering myself if there was any setting you could change with VAGCOM, in the Instrument Cluster, to disable the coolant temperature gauge distortion "feature". If you have a P3 gauge, it displays the real coolant temperature, as it reads it from the engine ECU.

[S4'ed]

So help me understand this, the thermostat can read the correct temp but not be opening properly?

No, the water thermostat just opens the coolant path to the radiator when the coolant is above a certain temperature. The coolant temperature sensor tells the instrument cluster what the coolant temperature is, for the gauge. There is another engine coolant temperature sensor that the ECU uses to measure the engine temperature.

[dizzlesizzle]

I'm pretty sure when you enable the lap timer with VAG it will show the engine oil temp on the top in the DIS. here is the coding:

Enable Lap Timer
[17 - Instruments] [Coding - 07] -> Long Coding Helper -> Byte 1
Bit 3 - Check the box for "Lap Timer active"

Also, another way that your t-stat might be on its way out or getting stuck either opening or closing correctly is you will loose hot air coming out of the vents while at idle. thats what was going on with my car and replacing the t-stat has fixed the issue. Either that or when they replaced the t-stat they actually bled the system properly.

[fitzydude]

Great timing on this thread!! The last couple nights I've noticed my fans have been coming too soon and staying on with outside temps around 40 degrees. My temp gauge isn't climbing past the middle yet, but tomorrow morning I've got to drive 13hrs which is terrible if my thermostat is failing. Today I'll pick up a thermostat from Audi, I'll bring my tools in case I need to replace the t-stat on the road. Do I need to drain all the coolant for this job or could I get away with partially draining the coolant??

So I monitored the temps with the torque app and they were getting above 230 with the fans on high. The coolant Gage finally started reading above half when the temp hit 240. I decided to go ahead and change the thermostat before the big trip..

Unfortunately I didn't realize a bolt held the thermostat and the water supply pipe together. I ended up breaking off the part of the pipe in the t-stat. New water pipe won't be in till next week so I went ahead and took the beater. Luckily I didn't attept this job on the road! It's easy enough but I would have been stranded when the pipe broke.

Surprisingly the old t-stat was the older version where the part number ended with AD. A couple of the tabs were broken when I pulled it out. The new tstat ends in AL, looks exactly the same as the crappy old one.

[dizzlesizzle]

I thought the older t-stats were made of plastic and was the cause of the issues. They new ones were made from a different material. I could be wrong.

[amz]

I thought the older t-stats were made of plastic and was the cause of the issues. They new ones were made from a different material. I could be wrong.

Are you thinking water pump? Those used to be plastic but have since switched to proper metal.

[antonioching1]

Trade in an get yourself a Honda German engineering is stupid!

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[GeoJoe]

Trade in an get yourself a Honda German engineering is stupid!

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[Dazman63]

Priceless!

[antonioching1]

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[DGVR6]

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Fail