jazzmegood

<center><img src="http://www.usatcorp.com/pics/car2.JPG"></center><p>Bought an '02 A8L a few months ago with 60K. Now has 65K. Great car, and I was able to troubleshoot and fix the seemingly common vacuum hose breakage that caused the CEL light to come on. Thanks to Vag-Com for helping me fix this without a trip to the dealer. Considering that I'm by no means a mechanic, I was impressed. However, now I've got a new problem.

About 2 weeks ago, I happened to look at the temp guage while driving to work on the interstate and noticed that it was above it's "normal tickmark" as I call it, the one located about 1/3 the way up the guage. This was the first time I'd EVER seen it above that mark.

I thought nothing of it, but started watching it more closely. Over the next couple days, it started getting a little higher, and within 3 days or so, it was at the halfway point of the dial when driving at full speed.

I checked the coolant which was a little bit above the minimum mark on the reservoir. I topped it off to the max mark, hoping that might solve the problem. Unfortunately, it didn't. This past weekend, I visited some friends out of town, about 250 miles away. I noticed at one point that the temp climbed up to the 2/3 tickmark and stayed steady there.

Since I had the AC on, I decided to turn the heat on full blast to see if that would change things and it did. The temp fell back down, almost all the way to the "normal tickmark". After seeing this, I turned off the heat, but also did not turn the AC back on. I rolled down the windows and drove the rest of the way with the guage steady at about the halfway point.

This morning's drive to work was much of the same, with the guage reaching almost the 2/3 tickmark before I turned off the AC. This time, even with the AC off, it still stayed steady at 2/3, although I was near the end of the drive, so it may not have had time to start coming down. When I got to work, I left the car running and checked under the hood. The electrical fan and the belt-driven fan I could see were running. I also noticed that the coolant reservoir was sitting at max, which struck me as a bit odd. I'm by no means a mechanic, but I would think an engine running at 2/3 the way towards Hot would have pulled more coolant into the engine, therefore leaving the reservoir lower than max point. I may be totally wrong on this however.

That's basically it. The CEL light isn't on, but I will check Vag-Com tonight to see if it shows any codes. My only thoughts are that it could be:

Stuck thermostat
Air pocket in cooling system
Water Pump

Anyone have any suggestions, or experienced this before? Is it safe to drive the car with the guage at the 2/3 mark, or am I damaging the engine and need to put it in the shop right away?

Thanks for any info you may have.

Ramiro

have the same problem! anyone?

jazzmegood

I also posted this question over in the D2 forum and got a lot more response. It was either the water pump or t-stat. It was coming due for a timing belt change, so I just had it all done at once. It runs perfectly fine now. Total cost was about $1100 for the whole job, which was:

Timing Belt
Water Pump
Thermostat
Tensioners/Rollers
Coolant Flush
etc.

Price may vary depending on where you're located. I'm in the Raleigh NC area.

rovcontrolguy

Thanks for the info. My '00 A6 4.2 is doing a similar thing. Now I have some idea of what I'm facing cost-wise.

dogolf

Australia calling...I had a 2000 A8 with similar problem, temp went from a steady 90 to a steady 100 (centigrade) Turns out that the impellor on these suckers was changed from brass to plastic and the plastic separated from the main drive...the exact same item/problem on BMWs...so if it's a steady high temp, I guess you need to upgrade the impellor...and while you have the nose off the car, makes goods sense to do the other belts. Oscar Bevz, Sydney Australia...

David Giannandrea

You might check the temperature sensor that turns the fan on, there are 2 speed stages, sounds like 1st stage is failing. The a/c probably turns the fan on regardless of the fan-temp-switch and this explains why you can cool the car down. Broken plastic impellor in the water pump would not allow you to recover to normal temp.