Crankcase pressure

My 2001 Lanos had 248k miles on it when I had a rebuilt engine installed. The original engine was leaking coolant from the head gasket at at the flywheel end - no internal leaks, just onto the bell housing. The replacement engine builds up so much pressure in the crankcase that it blows oil past the oil cap gasket onto the valve cover. With the oil cap off and engine running, I can feel steady pulses of pressure when I should be feeling a vacuum. The PCV valve has been replaced and three mechanics have not been able to cure the problem.

Has anybody experienced a similar issue? I'm almost ready to find a cliff or a very deep body of water.

Blow-by from a collapsed ring?

Thanks for the response, SleepyHead. The pressure with the oil cap off is light and steady. The pulses are evenly space and seem to be in time with the firing of all four cylinders. Compression (dry and wet) was good on all four cylinders. When I get time, I'm going to verify that there is suction in the tube to the intake manifold. There must be a solution to this problem.

try doing a leakdown test. I just had that problem, good compression, and when I pulled the pistions , I found a broken ring. I had poured some oil in each cyl, and the one with the broken ring drained, which tipped me off that something was wrong there.

Thanks, Bowens. A leakdown test revealed leakage in #4 cylinder. I'll just drive the car until it quits, then start looking for that cliff.