High compression in #3
High compression in #3
85 mercruiser mcm140, a395548, has high compression in cyl #3. Compression in 1,2 & 4 are between 140-150psi, in #3 it's 180. It blows the gasket out on the outter wall under the manifold, the thinnest part, All pistons are the same, no scaring on the cyl walls, valves look good, doesn't burn oil, over all runs great. The only mod is an ignition conversion and 1.5ohm 40,000v coil. Passes leak test, I replaced the head gasket today for the 3rd time, followed the correct torque sequence and torque settings. I am truly stumped.