How to diagnose water in engine (OMC 5.7 1989)

[cmyers_uk]

My friends boat has a 1989 OMC engine 5.7litre and water has got into the engine on one bank but not the other. With my limited knowledge I assumed that it may be because of the exhaust manifolds corroding? Please could anybody advise what are the normal causes of water into the engine and if there are some obvious thinigs to look at first. The engine had just been rebuilt apparently by the 'Car' engine expert!.

Many Thanks

Chris

 

[Haut Medoc]

Re: How to diagnose water in engine (OMC 5.7 1989)

Yup, I would look at the manifold, riser & the mating surfaces between them.....
If they are more than 7 years old replace them......
Water intrusion on one side is a dead giveaway.......​

 

[thrasher]

Re: How to diagnose water in engine (OMC 5.7 1989)

I would also check your flapper valves. I had water in one bank of my engine and when I removed the risers I found the flapper valve was missing for the bank that had water in it.. Found the flapper valve in the bottom of the Y piece!! Simple fix.. It might be the manifolds, but I would look for the flapper first (much cheaper if that is the cause). Of course that was for a Mercury engine so this might not apply to an OMC.

Gary