Checked compression on my 119,000km 3.9mpi last night and was pleased with tight motor reading between 1150 and 1190kpa (factory minimum is 1010) until No 6 came in at 950.
Put some oil in and cranked up to 1125, so only possibility I can see is rings, and probably left factory like that as difficult to see why only one cylinder was down. No sign of head gasket leaking in that area or anywhere much else. Exhaust valve in good condition, to extent I could see it through plug hole. Motor was warm but not at operating temperature, so might have influenced it a bit.
I remember testing my 4.1 once with similar results, but there were two adjacent cylinders down and even though oil in cylinder increased compression it turned out to be head gasket as suggested by adjacent cylinders.
Any possibilities other than rings this time round?
Put some oil in and cranked up to 1125, so only possibility I can see is rings, and probably left factory like that as difficult to see why only one cylinder was down. No sign of head gasket leaking in that area or anywhere much else. Exhaust valve in good condition, to extent I could see it through plug hole. Motor was warm but not at operating temperature, so might have influenced it a bit.
I remember testing my 4.1 once with similar results, but there were two adjacent cylinders down and even though oil in cylinder increased compression it turned out to be head gasket as suggested by adjacent cylinders.
Any possibilities other than rings this time round?