I 87 gn motor that I had rebuilt about 2 years ago, I don't drive the car on the street it is primarily a track car. So it doesn't have a lot of street miles but it does have a lot of strip time. I started to blow head gaskets last year. My engine builder told me to use the stock gaskets because he said he that the stock gaskets would give before any hard parts would. the best i got out of the motor was 11.0 @120mph. I followed the procedures using the head sealing tips under resources. they blew again. I replaced them again, each time sending the heads out(champion aluminum race fully ported} to be checked. they would come back with a clean bill of health. I started it up went for a ride and now I have oil spewing out of the dip stick tube and I blew the oil breather off the d/s valve cover. Even at idle its blowing out oil. Help! to me it sounds like the rings are bad. I did a compression check and they were all at 120. also when I turn the engine off you here a hissing sound as though compression is getting past the rings. anybody have any ideas!
Either another headgasket is blown or you've damaged a piston/ring with detonation (or some other failure mode).
There must be a cause, so I wonder if the block itself has a bad surface, or if it's simply a matter of not enough fuel/octane/too much boost?
I just replaced the head gaskets. After that I took it for a ride and that's when I noticed the oil blowing out and the breather blew off. Maybe there is a bad surface on the block. I put a straight edge on the block when I had the heads off and it did not seem to be off. It seems like this all stemmed from a run when I was at englishtown. I ran a few 11.25's and the track was biting good. I leave off a trans brake. I went up to the line and hit the button, staged, and blew the left rear axle when I let go of the button, the motor soared past the rev limiter. I don't know how high it went. Since then I have been replacing headgaskets. maybe something happen to the rings on that one. or what ever I did on that pass has gotten worse. I have a fuel system in the car with an aeromotive pump and a cell. I should be getting enough fuel, and I only run 116 in it. I run 28- 30 psi of boost with a stage five turbonetics ball bearing turbo.
that may be a bit much boost for stock head gasket set up, not sure on that, but I dont really see much of a ring problem if u have 120 psi across the board, there should be a clear drop in psi in one or more cylinders. im sure u dont want to hear this but it sounds like it needs to come out and apart for close visual inspection. so to give you a reason to go on w this lets do this, pull the valve covers off and loosen the rocker shafts to make completly sure that all the valves are closed, pull all of the plugs and one by one aply shop air pressure to each cyl. until u have your major blow by. then you will know for sure what cyl or cylinders has a problem. the reason all valves need to be shut is so there is no two ways about it its that cyl, also you will find poorly sealing valves. its to early to say for sure but im thinking your going to find a nice size crack somewhere or a chunk of block missing. if you are changing your own head gaskets this little test should be a breeze for you, drop me a line if you want to discus this further. good luck