Quick bit of background. Recently (in the last 15k miles) changed the waterpump and T-stat.

This week, my car temp has been going up more than normal. Normal is at midway. Now it goes to the next notch and sometimes a bit more. I have so far not had any beeps from the display to say engine overheating, but I'm concerned non-the-less.

Coolant level is ok. I have three fans in the engine bay. The motor driven clutch fan seems to be spinning happily all the time. AC fan starts when I start the AC on, as expected. I can't tell when and if the third fan is supposed to start. This is the V8 and it definetly has 3 fans.

Starting the AC on helps reduce the temp a little, which I would expect, but still not down to half way. Driving on the highway keeps the temp close to mid point, but still higher than normal.

Searched what I could, but without a clear answer. For starters, when is the third fan supposed to come on? What's the easiest way to check that it is working as there isn't a lot of space there.

I'm currently suspecting this 'third fan', a relay or a fuse. I'm hoping it is something simple.

Sorry for the long post, but I thought I would give as much info as I could.

 

go with the rs6 wheels!! the rs4's in my opinion go good with the a4 but not with the a6 idk.. love my rs6 reps though

 

ik that with your t-stat replacement you used new fluid.. but have you tried an actualy coolant system flush?

 

The waterpump and t-stat were done in the summer, along with a couple of welds done to the radiator. Althought the system wasn't completly flushed, I can't imagine how much would be left after doing those three jobs. I had no problems doing a 6 hr drive at 110 mph in the summer at 113 degrees F. So I would be surprised if the fluid was going to be the issue.

There was a funny incident trying to get G-12 fluid for this. They ran out at the dealer. Not just the Audi dealer, the VW dealer, the Seat dealer and the Skoda dealer. Can you image a county with 25 million people running out of G-12!!! I couldn't believe it. Not only that, they couldn't give a date when it would be in. I had to use an alternative pink one (Toyota) recommended by an independent Audi tech as well as the Audi service desk.

I did think about the possibility of gelling because of the two mixtures, but again, I think it is not likely.

 

Well, it turned out that the t-stat was getting stuck closed. It finally got stuck closed and it cost a fortune to have a 20 t-stat changed. It's basically almost like doing the timing belt job again. Clever design. I wonder who came up with it