"t" wrote in
:

mercruiser (chevery) 350. Compressions test showed 1 cylinder had 0.
All others were ok. Engine backfires and sputters. Doesn't seem to
be leaking much oil if any at all.

here's what I tried:

--
Pulled the valve cover. Valve is moving up and down.
cranked the motor until the valves were closed, blew compressed air in
spark plug hole, no air came out the exhaust or intake.
yanked the head off, no hole in cylinder (that I can see), head gasket
look ok from what I could tell

Any suggestions?




This is *really* inlikely, but since it happened to me once, I'll tell
you.

Check to make sure that the piston is actually moving. I had a piston
split in half once. The top stayed up, the skirt stayed on the wrist
pin. Until I cranked with the head off, I could not figure our what
happened. You could have broken a rod. Depending on where it broke,
that could act as you describe...

On the happier side, it could be a broken ring. You'd get almost 0
compression on some designs...

Steve