I've done my third head gasket replacement,(95 Civic DX 1500 cc)this time milling the head to eliminate any warpage (probably should've done it the first time). It was disappearing coolant that led overheating problems that lead to myhead gasket jobs, but thrown in the mix were a very mechanically disinclined son who drives this thing and doesn't fully comprehend what an overheating event does to the overall health of a motor. Cracked radiator, water pump the went kaput etc etc is probably where it all started. But with all this stress,and the recent head milling, the engine is smoking andI'm ready to throw inthe towel. I did a compression check, varies from 140 to 152 at operating temp, squirt in a little oil and pressure went up to 190's. By the 4th crank of the engine each cylinder was at max pressure (60 to 80 to110 to 140's). One thing I notice at the last head gasket change (only a couple weeks ago) whenI topped off the oil by openning the valve cover cap to pour in oil, somethingI never notice before on any car I owned happened. I couldn't pour in oil while the engine was on without getting sprayed with alot of oil coming out of that opening. It seems like the top of the head it under pressure, and I'm thinking if thisis a malfunction, the oil is probably getting pressurized right down through the valve train into the cylinders and thats why Ihave an engine that smokes to the point I need to do something. Is this pressurize situation normal or is this my "smoking gun"?

 

The smoke from the tailpipe, is it oil or water? The smoke coming out of the oil cap and the compression increasing a lot when you put oil in usually means that the piston rings are worn out.

 

Smoke is coming out the tailpipe, and smells like oil burning smoke as opposed to water vapor. No smoke coming out of valve cover oil fill,just spitting oil out of it. That seemed strange, all my other vehicles I could always add oil while it was running with out it being messy.

 

Valve stem seals perhaps???

For the smoking have you tried using a heavier weight of oil, like say 20w50?

As for the pressure, I've never had the cap off while running, so I can't verify that... it seems like it should not do that though, and that there is pressure where there should not be pressure... A bad valve stem seal could in theory allow cylinder pressure by it when the valve is open and thus could cause the oil spray you mention, as well as the smoking... I will skim the haynes manual for any more info on that...

Rings and valve stem seals are likely easily damaged in repeated high temp situations... I assume it was run hot for a while... I drove mine with the temp gauge pegged out for five miles when my head gasket blew, there was nowhere to stop, and still didn't manage to warp the head, so it must have been run a while, or it was just the luck of the draw... All I know is I've replaced my gasket once and since put 38k miles on the clock, and no problems with it since.

It also seems like the oil in the cylinder would only affect compression in the event a ring was leaking... it should not have any effect on a valve stem seal... so you may have a combination of problems...