350 with water in cylinders ???
 

A boating buddy has a 350 Volvo/Penta in his boat. On our last outing, the engine "dieseled" a lot when shut off. He said it had been doing this all summer. At the end of the day, the engine would not start, engine was hydro-locked, but he did not realize this at the time. Several days passed and he pulled the plugs to find the cylinders full of water. By this time, rust had already formed. He pulled the engine and tore it down. All looked good. He is re-assembling it now with new Vortec heads and upgrading the camshaft. His machine shop checked everything very thoroughly and all is OK. My concern is: Did the water enter the engine from reversion while engine was dieseling? Or does he have a leaking riser on his exhaust? Are there any other possibilities he needs to investigate? I would hate to see his new engine suffer another tragedy.

I have had similar problem. I have replaced risers/manifolds, timing system and am getting ready to have heads redone. My problem comes with startup. It will crank for a while and not turn over, then spin backward and suck in the water. I thought problem would be solved with the timing adjustment. It still did it one more time July 4. Since then, it has been ok. I know if through hull exhaust is possible, that would cure the problem. It is not possible for me. Good luck finding a cure.

Check out NEED ENGINE INFO in the Tech QandA this guy had H2O in his engine also. He got some good advice.
How old is the boat..how many hours and is it in salt water?
Let him know anytime it diesels you can have a lot of problems as a result.
Gator check your ignition system. Carbon tracking in the distrib. or a bad ignition module, etc. causing your firing on the wrong cylinder. Things are not supposed to run backwards, Ha HA
Good luck

Check the exhaust manifolds and risers. This is the most likely area to fail in this particular situation.
Good Luck

If you fix the dieseling problem, the water in engine problem will fix itself!

Steve H

The boat is a 1997, freshwater only, it has like 75 hours on it.
Thanks for the advice so far!

I believe the dieseling is caused by a high-idle from a sticking choke. He is swapping to a 4bbl marine carb while engine is out. I think that will fix the prob.
Thanks!

Also check the exhaust shutters/flaps in the "Y" pipe.