Running rough/misfire....blown head gasket?

[badfish488]

I have a 91 325i that suddenly started running very rough. I did a compression test..all cylinders had ~150psi except for 1. That 1 cylinder would read 0psi and then jump up to 90psi after the engine would turn over a few times. I'm thinking it's the head gasket but I'm not positive. It does blow white smoke every so often and the spark plug on that cylinder is oily/fouled. Should I pull the valve cover and see if the valve is stuck? What do you guys think?

[jlevie]

The compression test doesn't really tell you much about the head gasket. The low compression could be bad rings or a valve problem. A leak down test will tell more.

Check to see if there is a broken rocker.