Intake looks great from top and is in generally v. good condition. Of course
I cannot eliminate water getting into the intake through flame arrestor
(especially that I do not have a special cover that goes on top) but when
the engine is run on a water hose there is steam coming out of the outdrive
that would indicate some leak. Both head gaskets were replaced and the old
ones did not show any leakage or damage.
Here's my trouble:
- can't imagine cracked block as this would not fill the cylinders with
water (not all of them at once), or will it?
- head gaskets replaced, intake manifold inspected and intake gaskets
replaced (no crack signs from the bottom)
- rust in all intake passages from carb and under the carb
- rust in the head intakes, both sides especially the middle passages
closest to the carb
- water in the oil, oil filter and crankcase
- cylinders filled with fresh water (quite a lot)
- no indication of a cracked block (on the outside)
- no watermarks on the flame arrestor indicating water dripping from the
engine cover
- steam from the exhaust (that eliminates water dripping into the intake)
- exhaust manifolds were cleaned and there are no rust marks inside
- the only rusted area is the bottom of the carb, inside of the intake
manifold and all cylinders/spark plugs.

I tried to look into every possibility and am still puzzled. Only
explanation would be a cracked intake manifold leaking into the intake
passages then via cylinders down into the crankcase. Am I wrong? How to
pinpoint the source of the problem?





"JamesgangNC" wrote in message
ink.net...
Possibly getting in thru the spark arrestor. Or a cracked/rusted out
intake
manifold.

"Paul" wrote in message
. cable.rogers.com...
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