Has this engine been overheated? If so all bets are off it could be any
water gasket surface especially the head! Or a cracked block/cylinder wall.
It is probably a problem of this nature and the dealer/mechanic is afraid he
may have to repair the engine under warranty and he doesn't want to. Have it
looked at by an independent mechanic.
I have run too many boats with thru transom, over the transom exhausts as
well as every conceivable through the leg and silent choice type setup.
Water and oil should not mix, period! In older boats, 5+ years old, it is
common for the risers to leak. There usually is a rust line at the joint.
This will cause water to drip back into the exhaust manifold and eventually
will find it's way to the cylinder and the oil. It is normal maintenance to
pull the manifolds and risers at 5 years to check. Some say just replace
them there going to go soon anyway, even if they look ok now. Salt water of
course makes this all that much worse!.
John
Marine mechanic for too many years
"Steve Lusardi" wrote in message
...
Ralph,
This valve timing thing is a wives tale. All gasoline engines have some
valve overlap. The overlap uses gas inertia to breathe better and increase
the vollumetric efficiency. Typically, high performance engines use 106
degree valve centers and torque/ mid-speed work engines use between 108
and 114 degree centers. In all these cases, gas direction reversal only
takes place at very low speed and low throttle settings. (idle) The term
for this is reversion. This is what causes carborators to become black. It
is exhaust deposits. This can be a problem if there is excessive exhaust
system back pressure. However, in a marine environment, this would never
cause water in the oil, even if water vapor was being ingested at low
speed, it would be exhausted on the next cycle. It might make the idle a
bit rough, but that is all. My experience indicates a faulty exhaust
manifold casting. Many of these are porous or cracked and the water
jacket, being higher than the head, allows water to leak into the exhaust
ports at shutdown and because the engine is stopped, the water will slowly
leak past the rings into the pan. Another responder mentioned a head
gasket leak and of course this is possible, but on a relatively new
engine, highly unlikely. To test for a faulty manifold casting, it is
necessary to use block off plates to the water jacket and charge the water
jacket with compressed air and watch for leakdown.
Steve
"Ralph Modica" wrote in message
...
Hello :
I have a 2003 Larson Cabrio 254 Cabin Crusier w/73 hours on the 5.7 Volvo
Penta
I/O.
Have recently discovered water in the engine oil. The dealer's mechanic
is
telling me this is "Normal" and may occur if the boat ingests water while
coming
down off-plane too rapidly or even if water is splashed too high while
putting
the boat in the water at a launch ramp.
Seems this is TOO easy an "explanation" for what I think is a defective
engine
gasket.
IF this IS something common, I'm amazed more people have not complained
to the
manufacturer's about designing their boats better to avoid water
ingestion.
I've also heard water ingestion is a common problem on Volvo 8-cylinder
I/O
engines. There is apparently a problem with valve timing being off - this
allows
the intake stroke to pull vacuum while an exhaust valve is still open,
thus
sucking water into the cylinders. Has anyone here heard of this or have
further
details ?
Thanks in advance !
Ralph
|