Water in combustion chamber ???

[Dinows]

I changed all 8 plugs and finally with a lot of cranking started my Mercruiser 350, 1987 engine. It ran ok but would not idel and restarted hard. I then noticed that the smoke coming from the valve cover vents seemed like a little steam so I shut it down, removed a couple of plugs and there was water at the base of the electrode (even though it was firing).It was Salt Water (I tasted it)Now I am really miffed as it is a closed system and the only thing that sees salt water are the risers, and I am not loosing any antifreeze. Any ideas
Thanks Dino

 

[Don S]

Re: Water in combustion chamber ???

Defective manifold, riser, or gasket surface between the two. Happens all the time, especially in salt water. The manifolds are usually good for about 8 years before needing replaced when used in salt water.

 

[Dinows]

Re: Water in combustion chamber ???

The risers were replaced about 9 years ago, could it just be them and not the exhaust manifolds
Thanks Dino

 

[Haut Medoc]

Re: Water in combustion chamber ???

It is either the riser itself or the joint between the manifold/riser.....
The manifold itself is still probably good, but you will need to pull them apart & see if the surface where it mates to the riser is good.....​

 

[Dinows]

Re: Water in combustion chamber ???

Well you said it was the riser you were right. Took it off today and it had a hole in it and the manifold was filled with water.One thing I dont understand is how the water was getting into the combustion chamber. The exhaust ports blow hot gasses out, so how does any water get in. If it was the intake manifold I could understand
Thanks Dino

 

[cgrooves]

Re: Water in combustion chamber ???

One thing I dont understand is how the water was getting into the combustion chamber. The exhaust ports blow hot gasses out, so how does any water get in. If it was the intake manifold I could understand
Thanks Dino

Water got into the exhaust manifold. Once you shut the engine down, it got into the chamber(s) where the exhaust valve(s) were open / partially open.