ticky

My 95Wrx Ra has been overheating, heater blowing cold air only.So I had sent the car for a diagnostic check. The company tried to carry out a pressure test but they were unable to do it successfully due to water coming out of the expansion tank bottle. But there final conclusion was head gasket or poss cracked heads. What i cannot under stand is that surely the hot water would eventually expand & want to come out some where. So I suppose they would clamp or by other means stop it from coming out. To carry out this pressure test. Is this company telling me bull..... or am i missing something again.

swan

If there is a leak as described then they wouldn't be able to do a pressure test as when they increase the pressure there is possibly air blowing past the gasket into your water system. This increase in pressure forces water from your header tank through to the filler bottle. Get a combustion test done - this will confirm or deny if air is indeed getting into your cooling system.

206CC

To pressure test the engine, you turn the crank until all the valves are closed in each of the cylinders..
Feed in compressed air via the spark plug hole, and watch for pressure drops.. If there is a drop then the head gasket will be leaking..
OR you may have one or more valves in that cylinder under test damaged/burnt or dodgy piston rings etc

However If the gasket is leaking into the water jacket then it will force coolant from the expansion tank as described..

I guess if it is overheating then one of the two gaskets will be shot..

Personnaly If that is the diagnosis then I would have both of them replaced anyway.. as its only an hour or so's extra work for the second head gasket

Scooby Technician