rtv or not to rtv?

[honey toes]

3.0 liter omc. motor is leaking water between the block and manifold. Changed gasket did not apply rtv to gasket. It is still leaking. I do not think it is leaking at the freeze out plugs but will check them this next time. Should I put high temp rtv on the gasket? Both sides or just one please advise?
I had issues with it last year running hot. Cleaned and machined manifold etc. All was good. Exhaust was leaking into water in the elbow. On muffs this year is was getting warm again as well. But not from the elbow as last year that area of leak looked good.. Thinking the block may have cracked or something. Last damn snow storm ice and snow avalanched off my barn roof and covered my boat below. How can you tell a cracked block? Inlet water pressure is good. But temp gauge was rising without leveling off. Any suggestions on what to look for, would be great. House full of teenagers want to get the Toes in the water again.

 

[honey toes]

I had boat out in March before the snow avalanche so the water was not drained. It did pop a few freeze out plugs on the manifold.

 

[chiefalen]

You have to pull the mani off again. There is a casting plug under there, and thats is a prime area for a crack. Mani could be cracked as well.

When you have it off take a look down the exhaust tube, have a flapper / shutter blocking the exhaust ?

Risers don't last forever, and the impeller in the drive changed when ?

T-stat loks like what. Where you boat would be nice info for us, and year of boat would help also.

I never use rtv on the mani gasket maybe a little grease. But if you feel the need i would use nothing but permetex aviation form a gasket it won't melt.

 

[o2batsea]

Whatever the issue it does not sound good. I would venture a guess and say that the block has gone. Likely a crack in the water jacket. There is a dye kit that will let you see where the water is leaking.