Hi Dan,
John offers some good troubleshooting tips... A few things to add:
First the obvious, don't start it until you're sure you know what's wrong.
As far as dropping a valve seat and having it bounce around damaging the
cylinder, don't worry about that. The seat ID is smaller than the valve head
and can't slip off, however it might hold the valve open enough to hit the
piston. My experience with this was the seat came all the way out of the
head, holding the valve open about 0.25" and still didn't hit the piston -
YMMV. I had not heard of John's approach with the rubber hose - very clever
and if you can't find the problem you can beat the engine with the hose
until it confesses. I have a leak down tester that I haven't tried out, it
will detect small compression leaks but then you are not looking at a subtle
problem. If you want to give it a try let me know, I wouldn't mind the drive
to Oakland in this nice weather. I would avoid using a conventional
compression tester since even at starter motor speed you might do more
damage.
Todd
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