Audi 5.2 V10 random overheating

[Gabriel]

I am having a strange overheating issue with my Audi. It is an 5.2 V10 S6 from 2007 with about 115,000 miles on the odometer.

I have had the car for about a year and have never thus far had overheating issues until yesterday. I was driving normally and in light traffic until I had to stop for a red light. That is when I noticed that the coolant temp gauge was almost in the red. The light turned green and I started driving again, but the needle stayed pinned there almost at the max. I immediately put all of the windows down and turned the heat to full blast at which point the needle when right to the middle where it supposed to be in about 2-3 seconds. At the first possibility I stopped the car and checked the obvious stuff. Coolant was present and properly topped off, where has always been, both electric fans where spinning at 100%. Anyway, I turned the engine off and let it cool down for about an hour then went on my way home about 30 min drive in light-moderate traffic with the AC on and the car was fine. Today I went for a drive again intent on stressing the system as much as possible to see if this happens again. Put the AC on at full blast, drove in moderate-heavy traffic and it took about 2h for the car to overheat, but same as before it happened all of a sudden without any warning. Just as the gauge was in the middle it went straight to red in just about 1-2 seconds. When the heater is turned to high it goes down just as fast. Doesn’t seem to be speed dependent which makes sense since the fans are running at full speed.

– Coolant was properly bled last time the system was worked on, I replaced the expansion tank about 6 months back.
– There is no coolant in the oil
– No leaks, the fluid is where it has been when I last topped it off

Do you guys have any ideas or suggestions?

• This topic was modified 3 years, 9 months ago by Gabriel.

Topic

[Jeffrey Voight]

First thought is a bad thermostat.

[Author]

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