Where do I find a cooler thermostat for RS6 C5 ?

[RS8]

I want a cooler thermostat, it should be below 80 celsius = 176 fahrenheit
so maybe 70 celsius = 158 fahrenheit will work for me?
But where can i buy one?

I have a new Valeo water pump and 80 degress celsius termostat now but it dosen't work for me?

If I stand still at idle so I can see in VAG-COM that the temperature goes up, and fans start blowing but it takes time before the thermostat opens?


When VAG-COM shows 100 degrees Celsius so the thermostat opens, I have also changed the temperature sensor but it made no difference.
(I have a temperature sensor at the end of the water cooler so I can see on my gauge when the temperature increases = thermostat has opened.)



I tried to boil the thermostat before I installed and it open properly.

Now I want to try with a cooler thermostat.

[mik15]

i am not sure if these could be used, but i've came across when was looking for a thermostat for my other car, A8 D2 4.2Q...

made by Mishimoto - MMTSVR693L -71C

made by Mahle-Behr - 075121113D 71D - 71C

my guess is that it might work on the RS6 since the base 4.2 egine is the same...

though you being in Sweden where is cold can't really see why would you need it....i am running the 82C one here

[Zorb]

Thermostats don't work instantly, nor are they binary devices. What's the temperature like 30 seconds after the thermostat opens? Where does it maintain equilibrium?

[RS8]

If nothing has happened after I installed the thermostat or water temp sensor? so it seems that there is a big temperature difference between where the thermostat sits against where the temp sensor is located in the tube behind the engine.

Because in vag-com I can read that the engine temp is 100 degress celsius but my water cooler is cold?

I find it strange that my water temp can go up to 100 ° C at idle when I have a 80 ° C thermostat?

Can anyone of you testing with vag-com and see how high your water temperature goes up to when you stand still at idle?

[mik15]

i have never seen it over 99-100C in vag-com, and this is at idling with 50C outside in the summer here...it is the same when the weather cools down as well, for example now having 30C outside the vag-com reads the same 99-100C at idling....

i have the 82C T-stat and the additional radiators as part of the super hot climate country package...

[UrS6]

If nothing has happened after I installed the thermostat or water temp sensor? so it seems that there is a big temperature difference between where the thermostat sits against where the temp sensor is located in the tube behind the engine.

Because in vag-com I can read that the engine temp is 100 degress celsius but my water cooler is cold?

I find it strange that my water temp can go up to 100 ° C at idle when I have a 80 ° C thermostat?

Can anyone of you testing with vag-com and see how high your water temperature goes up to when you stand still at idle?

An 80'degree thermostat doesn't mean it will limit the temperature to 80. It just makes the coolant go through the radiator once it opens. Also, putting a thermostat in that is too cool may cause the car to run too rich if it's still in warm up mode. I'm not sure where that threshold is or if 70 degrees is too cold. Are you sure you are not trying to fix a problem that doesn't exist?

[RS8]

Something is very strange.


My outside temp now in Sweden is only +5 °C


I started my car cold and let it idle all the way and at 95°C my fan starts blowing on a cold water cooler so the temperature continues to go all the way up to 105°C and fan 1 is now blowing for 95,7% and fan 2 is working at 61,2% capacity.
But my temp after water cooler is only 27°C


I have an intake temp on 48°C


First when I start to rev and hold it to 2000rpm for a while, then I see that my thermostat opens and the temperature after water cooler goes up all the way to 87°C
and then vag-com shows 90°C and my fans have stopped.

[RS8]

Another question what does it say on your car in vag-com in engine
measurements of group 134 with the engine running.



<tbody>
134

Temperature





Oil temperature

Ambient temperature

Intake air temperature

Engine outlet temperature





[°C]

[°C]

[°C]

[°C]


</tbody>


Do you see your correct oil temp? Ambient temp? and Engine outlet temp?

[G2]

Because in vag-com I can read that the engine temp is 100 degress celsius but my water cooler is cold?

I find it strange that my water temp can go up to 100 ° C at idle when I have a 80 ° C thermostat?

Can anyone of you testing with vag-com and see how high your water temperature goes up to when you stand still at idle?


If you want to get scientific, use an IR temp gun to measure various locations.

The t-stat temp is the opening point. It does not prevent an engine from becoming hotter. It is simply a valve the opens based on temperature- and is constantly changing.

I see 195-205F at idle fully heat soaked. And about 185F on the freeway. Search the forum for more info-- think I posted a bunch of info last year.

Using a colder t-stat may cause DTC's. It may reduce MPG. It may increase PCV contamination. if that happens, it will increase engine contamination and wear. If it's a race car, then anything goes....

[RS8]

I have now tested with IR temp gun and I have 100°C = 212 °F on the water pipe behind my engine at idle and that is the same what I can see in vag-com.
And on freeway it says 90 °C = 194 °F in vag-com
Lowest freeway temp I found in my me7logger logs is 87 °C = 188 °F

And that is with my 80 °C t-stat and a new Valeo waterpump with metal shovel and not plastic!

I think I will try to find a 75 °C thermostat to test with.

[scottmandu]

Although I am unfamiliar with how the RS6 software is with a great many other cars, a cooler thermostat will cause the ECM to think it is in warm up mode and inject excess fuel into the cylinders. In some cars (ford 5.0's in particular) the fuel was so great that the cylinders would be washed down and cylinder wear would be so great the engine needed an overhaul in as little as 20-30,000 miles.

[G2]

RS8, that info looks like where it should be. Very curious what the reasoning is for making it run cooler? Lots of power? DTC's? Again, using a colder t-stat will not necessarily reduce the temperature. Unless it's winter.

Might want to focus on preventing heat soak instead. These cars have issues in that department...

[RS8]

I have a temp sensor on the end of my water cooler, the problem I see is that the temperature starts to rise that means my thermostat has opened but only when I have 100 ° C in vag-com= on the green temperature sensor behind the engine.
But the fan starts already at 95 ° C and blows for full on a cold cooler?


Even though it is winter and cold outside, the temperature goes up to 100 ° C at idle and fans blowing at full speed on a cold cooler?
Thus, the thermostat opens too late, but then it also seems to be poorly flow at idle because if I keep 1000-1500rpm I can see that the thermostat opens earlier and then keeps the engine at 90-95 ° C without starting the fans.
My fan start and stops at 96 ° C


So if I can get the thermostat to open earlier, then it don't need to start the fan because the cold water from the radiator will cool down my engine.
and about "warm-up mode" it ends somewhere after 70-80 ° C, so if I will have only 80-85 ° C when I'm driving, it will not be a problem.


So what I want is to be able to stand on idle, without my fans starting all the time.
(especially now in the winter when it's cold and snow outside)


EDIT:
I was out and test drove now in the cold -5 ° C = 23 fahrenheit, but I had to drive slowly because it is slippery with summer tires in the snow :)
But even though I drive in 50km/h, I see that the temperature in the VAG-COM is between 95-100 ° C ?
and the fans are activated but I have only 20 ° C (68 fahrenheit) after the water cooler, so something must be wrong with my new t-stat?

[G2]

Almost makes me think there's an air pocket.... Also, what band of t-stat was used? During the summer my car would reach 200-205F at idle (ECT via scanner). The fans would cycle on low for a minute then turn off.

I spent 2 hrs cleaning the radiator, charge coolers, and A/C condenser on my A4. Made no difference, but the point is everything needs to work. Perfectly on an RS6.

Far as the fan running a lot in the cold at low speed, that's fairly normal from what I've seen in my RS6 and other German cars I've owned. Even in the snow. 50kph/30mph will barely hold 4th gear; 3rd gear is more likely-- oh right, you've got a manual (try different gears?). That's more engine heat in effect and going too slowly for these cars for ram air to help much, if at all. Maybe remove the undertray/splash guard, if not already done. This helps my A/C work better in the summer.

Bet I could easily figure out the problem in person. Dealt with similar cooling issues on a C5 S6 and RS6 (2) this summer. Curious what you find out being that's there's an ocean in the middle of things.

"better intake camshafts"...? From a S6 or S8?