Has anyone experienced similar to the following and can shed any light on
the cause, before I either refit my cylinder head or take my piston out to
check the rings?
Compression test (engine cold & all plugs out) showed five cylinders within
the range 175 to 185 psi, but number 4 cylinder was 110 psi. I squirted some
oil in the plug hole and checked again an it went up to 135 psi.
On removing the head I can't find any reason for the drop - valves, head &
block all appear fine. The bore does not have any undue marks and is still
holding the oil that I squirted into it. The head gasket does not show any
sign of leaking ( and there are no other signs such as oil in the water).
The vehicle has done 178k miles and this is the first time that the engine
has been worked on other than tappet adjusting etc. I can refit the head (
now that I have re-ground the valves), assuming that the gasket has
microscopic leaks with being so old, or should I check the piston first (and
save the time & effort of having to take the head off again if the psi is
Any experienced input would be welcome.