350 Mercruiser got water in back cylinders

[buffmont]

Hello , Tried starting my 350 with the muffs on water on gently, it locked up and would not spin, removed the plugs and found water in back cylinders.

This happened before and I had the flapper valves replaced and the riser gaskets replaced. Ran good last summer.

What other source of water can enter cylinders when the muffs are on ? It has freshwater cooling too. Engine spins over with plugs out.

I want to try this : Replace plugs and start motor a few seconds with muff water off, as soon as it starts then I am going to turn the water on so I dont ruin the impeller.

Any input will be appreciated as the marine dealer is treating me like the Golden Goose.

 

[fastjeff]

Might be a gasket leak at the manifolds / riser joints.


Jeff

 

[Bt Doctur]

Ok, what is coming out of the plug holes, taste it AF liquid or water. In the back cylinders meaning the 2 all the way to the rear on each side 6,8,5,7 or just the rear cylinder on each side 8, 7
AF liquid can be a bad head gasket or a cracked manifold if the manifold is cooled by the AF side , plain water can be the elbow gasket or elbow failure

 

[jsledd45]

It could be gaskets or look for a crack in manifolds, could be hairline, but something else to think about it water inversion. Does the motor have an aftermarket cam? I’ve seen it first hand when my buddy wanted to put a bigger cam in his motor. Under idel he got water inversion in the cylinders. Now before shutting motor off he revs it a couple times in neutral to blow it out.