After taking the boat out just a few times this your I couldn't crank the
engine anymore. Replaced the starter, removed all spark plugs, cranked and
fount all cylinders in a 5L V8 OMC 305 engine flooded. Pumped out water,
flushed cyl. (sprayed inside the cylinders and cranked) with WD-40 few times
until dry and finally sprayed 1 can of fogging oil into all 8 cylinders. I
pulled the intake manifold and there is lots of rust in the intake passages
in both, intake manifold and both cylinder heads. Since all 8 cyl. were
flooded at the same time with fresh water I do not suspect exhaust.
(verified by creating a closed loop coolant system and eliminating exhaust
altogether). Same issue. I also noticed rust on the bottom of the carb (4
barrel). My suspect is a leak between cooling passages and cylinders intakes
in the intake manifold. Can't also imagine how a cracked block would flood
all 8 cyl. at once. Please indicate how to test, diagnose the problem. Any
thoughts on the intake idea?
Thx,
Paul