SenaTTor

So I fill up my coolant expansion chamber and soon as I start the car it starts to pour - literally pour - coolant out of a little 'nipple' in the bottom/back of the expansion chamber. Buddy of mine believes that it's some kind of 'overfill' valve or something and that it's probably supposed to do that when it comes under pressure. I've had this car since 1998 and I've *never* seen it do anything like that... thoughts? Could it be a cracked or broken expansion chamber?

Problem is, I'm literally losing all my coolant. *ALL* of it. Once the system pressurizes it lasts about ten minutes and then the car starts to overheat. My friend believes it's the seal on the water pump (the weeper valve), but we haven't had a chance to tear down the whole front end to inspect it.

AudiMick

I had (2) new tanks in 10 years and 150,000 miles of driving.

It's pretty common.The tanks are cheap and are of poor quality.

Get a new cap too.

Huskerbob

You need a new expansion tank. See remarks below. They are cheap and easy to find and install. I put a new one on a few weeks ago.

Piski1982

I had to replace the tank on my 01 a4. it was like $56 from dealer. Before you do that make sure your not getting compression in the cooling system. Could be a bad head gasket?

Huskerbob

Did you find the problem?

twentysevenlitres

I agree with the other posters here.
It'll be the expansion tank.
The 'nipple' under the cap is the overflow drain.
If you take the cap off, the central section of the cap with the o-ring seal is the pressure sealing portion, the outer section is the overflow. And these correspond to the narrow and wide necks on the tank.
Check the expansion tank's narrow neck for a crack, or the o-ring seal on the cap for breakages or wear. Very common.

I wouldn't rule out a head gasket, but's its less likely.