2.7 Stage 3 High coolant temperature help

[cu52]

Background: I did a stage 3 build on my 04 allroad. I bought it with a bad clutch so I don’t know if it was running “hot” before or after the build.

I finished the build last year during fall/winter on a BEL block. Temperatures were getting up to 103c.

First I swapped in a 95c after run/front fan sensor and that has kept the temperatures to 95-97, and is running ever time I turn the allroad off.

Then I swapped the lower radiator sensor and the coolant sensor at back of block. No changes

Then I swapped the thermostat after a boil test to make sure it opens at the right temperature

Then installed a different radiator to see if there was low flow. Both radiators flowed really well. Getting ready to install a 80c thermostat to see if that brings the temperatures down. I don’t want to drive it as we are starting to get higher temps and stop and go traffic for 20+ miles 2x a day is not good.

Any thoughts on what could be causing the high temps but not actually overheating? Any areas to focus on reduced flow or how can I do a flow test through the entire system? I feel like the radiator exit is cooler than it should be but I have no basis of what that temp drop should be from inlet to outlet. Could a temp sensor just be reading High?

Any help or ideas are appreciated!

[Audibot]

Could a temp sensor just be reading High?

As I was reading through and seeing you eliminate item after item, that's what I was left thinking.

Are you going off the cluster or what VCDS is telling you? I'm wondering if one of two coolant sensors in the rear pipe has an issue and stops reading correctly when close to temperature. Other than that, maybe you're running lean and so it's extra hot?

[cu52]

As I was reading through and seeing you eliminate item after item, that's what I was left thinking.

Are you going off the cluster or what VCDS is telling you? I'm wondering if one of two coolant sensors in the rear pipe has an issue and stops reading correctly when close to temperature. Other than that, maybe you're running lean and so it's extra hot?

Going off of VCDS and the climate control menu which are within 1-2c. I do need an AFR gauge to verify if I am lean (Ordered, will be here friday), I dont think that is the case, but maybe I should check that before swapping in a 80c thermostat.

[cu52]

Update. No good news and now more confused.

I put in the 80c thermostat and it lowered the temperatures down a little but not enough to work. Drove it on a warmer day at 87-90 f and got up to 99c again. So still an issue.

Put in a new coolant sensor as I had a code at the last drive 2 weeks ago 16502 - Engine Coolant Temp. Sensor (URO this time) and took it for a drive tonight. Using the radio controls to check temperature against the gauge I was struggling to get to 70c (using 80c thermostat)

When I was done with the drive I was thinking well the thermostat is working temps are lower.... Turn off the car and walk toward the front and the afterrun fans /aux water pump were running. I have the lower temp sensor it which is 95c i believe. I tried checking temperatures with my laser thermometer but I now no longer trust that based on the wild results I got including 80 at the top coolant pipes to spikes of 120c just a couple minutes later, all while the coolant sensor G62 showed 72c.

Stuggling here, really need some help and I just want to drive this but temps outside are mid 90's now.

Below is what I was seeing:

[SteelyS6]

Maybe try cleaning out the rad fins, you would be surprised how much fine dirt, bug guts and other assorted garbage can accumulate in there over time. Viscous fan still or EFK?

Just noticed you said you swapped in a different rad.

[cu52]

Maybe try cleaning out the rad fins, you would be surprised how much fine dirt, bug guts and other assorted garbage can accumulate in there over time. Viscous fan still or EFK?

Just noticed you said you swapped in a different rad.

Swapped the rad and had sprayed it with the pressure washer and flushed it out before install as well as the a/c condenser.

Still viscus fan.

[Ali]

maybe the viscus fan clutch is failing.

[cu52]

maybe the viscus fan clutch is failing.

It seems pretty strong when at full temp. Swapped that out a couple times also with some other used ones. I do have 1 that has def. failed and is easy to stop at full temp.

[Ali]

Did you do a timing belt/water pump job on the motor when you did your build or know if it was ever done. Bad water pump is about the only thing left to check that you have not mentioned. Did you ever do a compression test?

[cu52]

Did you do a timing belt/water pump job on the motor when you did your build or know if it was ever done. Bad water pump is about the only thing left to check that you have not mentioned. Did you ever do a compression test?

Blauparts timing belt kit at the time I replaced clutch and went stage 3. Compression is good. If it was waterpump was bad, there would be other signs as well as the temp climbing like crazy as there would be no flow? Through all of this the needle has never been past 1/2 (with any of the previous G62 sensors)

[Ali]

Cant believe the gauge is that inaccurate that it has never moved from halfway. May have to vag mine to see how hot its really running. May be a good comparison since were both in the same town.

[cu52]

Cant believe the gauge is that inaccurate that it has never moved from halfway. May have to vag mine to see how hot its really running. May be a good comparison since were both in the same town.

Let me clarify. It starts all the way LEFT when cold, and was always at the center anywhere from 80C to 105c, most of the time I use the HVAC controls, channel 34 (might be 51 OR 57 on others according to the below links: to see the coolant temperatures laptop/VCDS is so cumbersome and I can access it anytime I am in the car. Only with the 80c thermostat did it not reach center as shown in yesterdays photo.

My other allroad (NO A/C as it needs charged) went to 110c the other day and had moved just 1 notch past center. I got that puppy cooled down fast, hoping that issue is no high speed aux fan due to no A/C. That one also has the Aux water pump delete, which I might have to source and install one if this keeps up. Gonna try to get that vacuumed and filled this weekend.

hvac menu info:
https://www.audiworld.com/forums/a6-...d-rpm-1727602/

https://www.audizine.com/forum/showt...ystery-problem

https://www.audiworld.com/tech/int5.shtml

[cu52]

Update HELP STILL NEEDED!

I have confirmed the temp in the cluster matches that of the ECU and that of the HVAC controller via VCDS for both cars. I have done a block test on both vehicles and fluid remains blue.

Stage 3 run's significantly hotter than it should with a 80c thermostat in it. Stock is about 99c which is better than it was since I did get the A/C charged and have higher fan power now.

Do I try new viscus clutch / Fan? Swap over to the A4/S4 early style? Like this with a new fan clutch also: https://www.rmeuropean.com/Products/...01E-MFG36.aspx

Anyone in the Denver area available to help me solve the problem on these two?

[m_haiser]

Why not ditch the fan clutch all together and run an E fan?

Sent from my Z917VL using Tapatalk

[cu52]

Why not ditch the fan clutch all together and run an E fan?

Sent from my Z917VL using Tapatalk

If I knew that would solve the issue I would, not convinced that is issue yet. Concerned it is something more serious and that will just be a bandaid. I want both cars running perfectly. Going to be trying to sell the stock one soon if I can get this solved.

Been looking at the JHM and the ProjectB5 kits.

[m_haiser]

Use jhm instructions and build your own it's far cheaper. There's a thread in here with a great step by step

Sent from my Z917VL using Tapatalk

[m_haiser]

this thread post #32

[smuggle khan]

There might be a air bubble in the coolant system.. idle the car and when temp is normal open the radiator cap and turn the heat all way up and let the heat run for 5 to 10 min and than close the cap and drive it around.. see if that helps..


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[cu52]

There might be a air bubble in the coolant system.. idle the car and when temp is normal open the radiator cap and turn the heat all way up and let the heat run for 5 to 10 min and than close the cap and drive it around.. see if that helps..


Sent from my iPhone using Audizine

I rebleed both cars again this weekend to be sure, no change.

Sent from my VS988 using Tapatalk

[julex]

Maybe you're OCDing here? What's your perceived overheating's symptoms? Are you dumping coolant from over pressurization of system caused by high coolant temps?

So far what you described is just a car that used to run at normal temps (Audis run hot!) and then after putting in brutally low thermostat you're really cool according to gauges/sensors... yet you think there is still a problem?

Anyway, #1 thing you should do is to buy Audi/DEALER temp sensor for back on engine, the one that feeds cluster and ECU (dual element). Only Audi original sensor works right, all the other brands (e.g. knock offs) are known to either give false readouts or fail in short order. Since you're relying on that temp sensor's readout as your sole source of truth, make sure you're have a good working one.

[cu52]

Maybe you're OCDing here? What's your perceived overheating's symptoms? Are you dumping coolant from over pressurization of system caused by high coolant temps?

So far what you described is just a car that used to run at normal temps (Audis run hot!) and then after putting in brutally low thermostat you're really cool according to gauges/sensors... yet you think there is still a problem?

Anyway, #1 thing you should do is to buy Audi/DEALER temp sensor for back on engine, the one that feeds cluster and ECU (dual element). Only Audi original sensor works right, all the other brands (e.g. knock offs) are known to either give false readouts or fail in short order. Since you're relying on that temp sensor's readout as your sole source of truth, make sure you're have a good working one.

I might have OCD!! But will let my doctor team decide confirm. Apparently I did not update this thread like I thought I did from Friday!

Stage 3 has the 80c thermostat and I put in a new OEM sensor last week. The one from URO was too large and did not fit. New OEM fit perfect and readings are dead center of the gauge even though it reads a lot hotter in VCDS.

Here were my results from Friday with the OEM 4 pin coolant sensor (pass side coolant crossover pipe)
It was 96f outside, in traffic downtown, temp went to 110c (still center of gauge cluster) with A/C on. Left downtown, with heat on full blast and 96f outside resulted in 101c (center of gauge cluster). Hit the HOV lane (60 MPH) and temp dropped to 89C with heat still on full blast. IAT was about 53 if I recall.

Stock allroad - runs at 99c with A/C on and has major heat soak as the shop that built the engine removed the aux pump, climbs to 110 or so and shows 1 tick past center after driving. Gonna install a aux pump hopefully this week to try and help the after run heat soak.

Of my three previous S4's (stock through stage 3 minus) none of them ever ran hot. Let along at near 100c with a 80c thermostat installed.

[Gogeees]

Are you sure the extra rad fan and condensor fan are working? Both my fans were not running on my 4.2L V8 and it would overheat in stop and go. Replaced both and have had no issues, even driving this weekend in stop and go in Arizona @ 115 F.

[m_haiser]

or a restriction of flow somewhere in the cooling system? try flushing the rad maybe or when was the last TB/water pump service?

[cu52]

Are you sure the extra rad fan and condensor fan are working? Both my fans were not running on my 4.2L V8 and it would overheat in stop and go. Replaced both and have had no issues, even driving this weekend in stop and go in Arizona @ 115 F.

Yes, both electric fans operate on both vehicles.

Sent from my VS988 using Tapatalk

[cu52]

or a restriction of flow somewhere in the cooling system? try flushing the rad maybe or when was the last TB/water pump service?

Flushed and then changed radiator (used but good flow) on the Stage 3 previously. Unless both have blocked fins. But I had vacuumed / blew them both out before i put engines back in. Both have brand new thermostats, waterpumps, full timing kits.

Where else could I have a restriction in the system. The stage 3 is running 30c warmer than it should be!