I took it apart already. It wasn't perfect as it lacked caps to make it good
for pressure testing. I lead the engine water inlet into the bucket. Both
outlets on the thermostat housing were connected with the "T" connector and
the outlet was also put into the bucket. The engine was running with a
closed loop feeding itself from the bucket (also spitting out into it).
About 10-15 min. into this the engine was reaching its temperature's
"operating range" mid-point.. Impeller was out.
It ran pretty well so I was optimistic. That has proven to be short lived.

Yesterday I spoke with the engine rebuilder and his judgment was "bad
intake" (rusted through or cracked). For now I'm kind of tired with
rerigging the engine again to I've pretty much decided to replace the
intake. My approach is this:
it is a § 100 fix, if successful I'm set. Since after the intake replacement
I'd have to pressure test water-jacket anyway I decided to do it afterwards.
I'm going to get the vacuum tester and I'll have a better idea as to the
intake, valves, head gasket etc. performance. But that will be done after
the intake replacement. I'll also need to stop by a local church to make a
donation, just in case...

"rmcinnis" wrote in message
...

"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.

Does this mean that water came out of all 8 cylinders after yo had removed
the plugs?

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).

I am not sure what you mean here. How does creating a closed loop cooling
eliminate the exhaust? Did you create a closed loop cooling system, run
the
motor and have all 8 cylinders fill with water again?

When you ran the motor this way, did you not have any water running
through
the exhaust system?

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.

If I understand the situation properly it doesn't sound like the water
enters the cylinder(s) while the engine is running, but rather after the
engine is shut down. If you get water into one cylinder it is easy for it
to migrate to the other cylinders, all it takes is for the intake valve to
be open. The water will flow from the flooded cylinder up into the intake
manifold. At least one other intake valve will be open at the same time
which means it will flood also. When you crank the engine the remaining
cylinders will draw in any water remaining in the intake manifold and they
will flood as well.

You apparently have a leak between the water jacket and either a cylinder
directly or into the intake manifold. This could be from a gasket failure,
either the head gasket (fairly common failure) or the intake manifold
gasket
(pretty rare, but certainly possible). If the failure is in the head
gasket
a compression check should show which cylinder is the problem.

If the problem is not a gasket then I would bet that the intake manifold
has
rusted through to the cooling system. If you still have your "closed
system" rigged up try pressurizing it and seeing if it holds pressure.
This
is a standard test on radiator systems, and you can purchase a small pump
and pressure guage that installs in place of the radiator cap for this
purpose. The cooling system should be able to hold 13 PSI without any
significant loss.

Rod