Engine Failure

[Boatgal21]

I've recently inherited a boat and I'm at a loss as to why my engine won't start. The boat recently had a remanufactured long block 5.7 Mercruiser 350 Magnum 270 hp engine installed in it. When I tried to take the boat out, the engine started making a racket and then it failed.

My neighbor builds boats as a hobby and he took a look at the engine for me. He said there was water in one of the cylinders and also that there was water and oil up to the valve cover. He also told me that my exhaust manifolds were from the 7.4 Mercruiser engine (which was replaced with the remanu. 5.7 engine) and the manifolds weren't replaced with the remanufactured engine. Is that typical? Or should I have the exhaust manifolds replaced?

I'm not exactly sure what caused the problem with the engine, but before I take the boat to a marine mechanic, I want to make sure I have some idea what the problem is.

Any thoughts or comments are appreciated

 

[Bondo]

Re: Engine Failure

He also told me that my exhaust manifolds were from the 7.4 Mercruiser engine (which was replaced with the remanu. 5.7 engine) and the manifolds weren't replaced with the remanufactured engine. Is that typical?

Ayuh,... Welcome Aboard,... That's Impossible,... They won't interchange...

 

[TilliamWe]

Re: Engine Failure

Your neighbor is confused about some things, but is probably pointing in the right direction overall.

When there is water in the cylinder(s) of a marine engine, it is usually due to the failure of an exhaust manifold or exhaust riser.

When an engine is replaced with a remanufactured engine, that typically means the "longblock" was replaced. That means all the bolt on accessories (starter, alternator, power steering pump and yes exhaust manifolds) are re-used. So it is very likely that the exhaust manifolds were the ones that were on the previous engine. However, that previous engine could NOT have been a 7.4, because as Bond-o points out, exhaust manifolds from a 7.4 will not physically fit on a 5.7.

 

[grahamh]

Re: Engine Failure

I the engine started making a racket and then it failed.

That's usually a sign that something kind of serious went wrong, I think it's a little more internal then the manifolds. "Water and oil up to the valve covers" also sounds very bad indeed.

 

[jtybt]

Re: Engine Failure

Just so you get the right information...exhaust manifold/riser joint leaks RARELY gets water into the crankcase simply because water won't easily get past the rings.

 

[WIMUSKY]

Re: Engine Failure

A blown head gasket will get water in the cylinders too. When you heard a racket then it quit, that sounds like a catastrophic failure. Hopefully not.....