Hi,
I have a 1999 A4 with the 2.8L V6 and 160,000 miles. I have a problem I cannot track down. The car runs and cools fine, everything is great until I shut off the engine and then the coolant rises and overflows.

I read the forums and a lot of posts recommended replacing the coolant tank and cap, so that is done and it didn't fix anything.

One of the recurring themes that I have read is that it could be a head gasket causing pressure to build up, but the weird thing is that everything is fine until the engine is shut off.

Does anyone have any ideas of what else I can check?

thanks,
Gary

 

Make sure you have purged the coolant system of all the air. There are usually bleeder valves on the heater hoses where they pass through the firewall.

 

You are correct, there was air in the system. I warmed the car up and then opened the overflow tank, with the car running, I was able to add a lot more water/antifreeze and get all the air out. I was surprised, because I have emptied the system before and never run into this. No problems since.

thanks!

 

sorry to hear that, maybe you should replace the Water tank cover, hope it can help you.