Hey all,
After my 00 A6 4.2l sat for a year, we had the transmission replaced and the rear o2 sensor wires spliced back together (rodent damage). Now it is over heating and most of my mechanic budget is gone. Can anyone point me in the right direction for diagnosing this? The big fan that is crank driven spins all the time, the other 2 only when the climate control is running. It is getting hot both in traffic and on the highway. The coolant is also disappearing but I am not sure where it is going. When hot you can see the reservoir empty rapidly but barely drips underneath car. Lots of steam. Also there was CEL for coolant temp sensor circuit, turned out the sensor was never plugged into coolant reservoir. Cel gone, still overheating.
Any ideas much appreciated!!
Thanks!
Kristen

 

I'm no expert, just a guy who does most of his own work. If there's a minimal leak, and the coolant IS leaving the resevoir, it sounds like you can at least rule out your thermostat. I had an error code regarding a coolant issue a fw months ago. Replaced the engine temperature sensor first (cheapest solutions first $16). No dice. replaced the thermostat and fixed.
Try checking the lower coolant pipes to see if they are getting flow, and it may be worthwhile to see WHERE the leaks are. Sorry I couldn't offer more

 

Thank you! After quiet a bit of googling and observing the car while heating up, my guess is thermostat as well. Did you replace it yourself? If so was it on a similar enough model to share your process? I think the "leak" only exists when the fluid is so hot it's spewing out because of the thermostat being stuck closed.

 

Although at slow speeds/ idle it heats up extremely quickly but on the highway with ac running the problem almost doesn't exist. Which sounds like a fan issue after my reading. I have no idea where to find pretty much anything at this point so relying on the Internet to save my car!!