High Compression

[Kazoo]

Running very rough, middle 2 cylinder had oil in the combustion chamber. Did a compression test. Cold Dry was 250 - 275, cold wet was 290 - 300 with middle 2 the highest. I’ll do it again hot, but seems very high? Any thoughts?

[Daox]

What do you mean the middle two cylinders had oil in them?

[Elangford65]

Compression sounds good but it Sounds like oil blowby the oil ring might be degraded. When I did my engine tear down I found 3rd and 4th piston(closest to driver side) compression ring were good but the oil rings were degraded and oil was starting 2 seep into the cylinder walls. But the running rough at idle could be something as simple as needing a tune up(spark pulgs,wires) to replacing both O2 sensors. Also wouldn't hurt to run a full fuel system cleaner.

[OG-Lou]

My compression test was around 175 PSI. 250 to 300 sounds too high, or are you talking about another scale and not pounds per square inch?


Oil in the spark plug wells is somewhat common but shouldn't be there.