Gentlefolk;

 

Ive been here before discussing what I thought was a head gasket leak on my '99 Impreza with the 2.2L EJ22 engine. Finally got it to my local mechanic, and his thought that yes, while I am getting oil and coolant mixing, it is NOT coming from the head gasket, since there is no steaming on startup.

 

His notion is that it is mixing at the intake manifold.

 

The cooling system was flushed at the dealer's a few months ago, as part of the front main seal replacement... many $$$$$. There is a possibility, my mech sd., that improper or too corrosive a power flush could cause deterioration of the intake manifold gasket.

 

So, two questions:

 

Is this powerflushing/intake manifold gasket as source of oil/coolant mixing scenario likely?

 

And..

 

What is involved in intake manifold gasket replacement? Is it, like the head gasket, of sufficient complexity and expense that I should consider replacing the engine?

 

Thanks for any thoughts!

 

Don

there is absolutely no oil in the intake manifold, nor is there coolant. It's possible you may have an intake manifold leak, but it would not cause oil and coolant to mix.

Neither does your mechanic know anything about subarus nor did he bother to carefully look at the engine. I would find a new mechanic.

 

99obw

Well.. one of the reasons my mechanic is SO GOOD is that he freely admits to what he doesnt know. He has steered me to other mechs several times when one of our vehicles had a problem he was not sure how to resolve. He has given lots of free service to us, and the support has been wonderful.

 

And he has said he doesnt know Subarus, so he is extrapolating a lot of knowledge, and his current suggestion is to get an official diagnosis from the dealer.

 

Also, he sd. he saw no steam from the exhaust when he was looking at the car.. indicating to him there was no coolant in the combustion chamber (I _guess_ you can have a one-way fluid transfer, but I dont see how...).

 

Drove the car today,and it was overheating, couldnt vent the pressure in a controlled manner, so I ended up doing so in an uncontrolled manner.... rather spectacular.

 

But, Im 99.8% sure all this agnonizing is still gonna result in another engine.....

The head gaskets on our '99 2.5L Phase I failed with exhaust bubbles in the coolant, overheating, no oil in the coolant, no coolant in the oil, no steam out the exhaust. I fixed it myself and it runs great.

 

The subarus seem to commonly fail with combustion chamber gasses making their way into the cooling jacket. The high pressures in the combustion chamber are enough to push the gasses by the gaskets. The relatively low pressure of the coolant added to the imperfect vacuum in the cylinder during the intake stroke doesn't seem to be enough of a pressure differential to force the coolant into the combustion chamber.

 

Don't get too discouraged yet. If you keep overheating the engine you MAY end up needing a new one. I would get it to a competent mechanic ASAP.

 

99obw