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1996 Subaru Outback

I have a 1996 Subaru Outback that overheats. I have replaced the thermostat more than once, had the water pump checked, flushed the radiator–it still over heats. BUT when I remove the thermostat, the car does not overheat. I have also replaced the radiator. The car only has 155000 miles on it, and my mechanic is trying to tell me it needs a new engine. Any ideas out there? Should I take it to the dealership?

Does this car have the 2.2 Liter engine or the 2.5? Define “overheat.” Are you going by the gauge or does the radiator boil over?

Has anyone tested for leaking head gaskets? This is a common problem on high-mileage Subarus, especially with the 2.5 engine. Hard to believe you need a new engine. Maybe you need a new mechanic.

Both the by the guage, and that it is boiling over. It is a 2.5 liter engine. Thanks a bunch!

They tested the head gaskets for pressure, and the pressure was OK.

Are the radiator fans coming on when they should? At least one, if not both, fans should start running long before the radiator boils.

Did you put a new pressure cap on the radiator when it was replaced?

The coolant can be tested for signs of combustion gasses, which is another head gasket test.

Do you lose any coolant other than when it boils over?

If the mechanic was happy with the cylinder pressure test, why does he or she say you need a new engine? What is the mechanic’s diagnosis of the overheating problem?

It sure sounds like a headgasket leak to me but I hope I’m wrong. As it was already stated these models were prone to HG leaks. I would have the coolant tested to see if exhaust gases are getting into it.

I asked a friend about this, and he suggested I put a hole in the top of the thermostat in case it is airlocked. He works a lot on tractors and has had this happen.