1990 Audi 90

[jackpine]

My daughter's 1990 90 overheats within 10 minutes when at idle. Engine temperature gauge indicates normal temp. Coolant tank overflows and there is pressure from the top of the radiator into the tank through the overflow tube. A local mechanic suggests that the head gasket is bad though there is no oil in the coolant or water in the oil. Sparkplugs all look identical, light-brown in color. No "sweet" smell of anti-freeze from the exhaust. Any suggestions on testing for a bad head gasket?

Thanks for the help, this is my first post.

[maniacuV6]

i think that your radiator is the problem . Try to open the heat into the car and see if temperature is lowering . If so the problem is the radiator. I have the same problem because i put some antefreeze from another type(one has glicerin and another(i don't know ) and they make a chemical reaction and results a kind of dust in the radiator ........

[Roc4]

THis may sound stupid, but have you checked to see if your fan is turning on? I have to replace mine because it only comes on about half the time that it should.