Water leak around spark plug

[Alby1]

I have a 1984 Merc 50 4cyl. I noticed when I put the engine up for the winter that there was water trickling out around two of the spark plugs. When I rev the engine the leak is worst. Checked all the bolts and they were tight. Can any one tell me what happened? Is the cover bad? Did the engine blow a gasket? How serious is this problem? Thanks

 

[conan1]

Re: Water leak around spark plug

I had the same problem with my 1975 Merc 85hp motor. The water jacket gasket was bad. If the motor hasn't gotten hot and warped the head, I don't think it is a hard fix. I had it replaced but had to come back and retighten all the bolts after I ran it about 5 or 6 times. The major cost is labor, I think. Just my opinion. Good Luck

 

[*EdC*]

Re: Water leak around spark plug

If your motor is mainly used in salt water, it may be corrosion. I have a '70 85 hp. It's a 4 banger with a siminlar problem. I assume your's is a 3. Below is a photo of a 4 cylinder block with the block cover off. I'm not sure if your's is the same, but I'll explain what I found in mine. In the photo, notice the machined flat area at each of the plug holes. Corrosion can eat away at the diameter of the flat spots right down to the plug socket. The cover plate and the gasket have wider plug openings. Corrosoion will eat the flat spots beyond the gasket and water will pass through the space between the plug hole and cover hole allowing water to escape.
I'm no expert here! Some one that is better qualified may be able to offer a fix!... Me, I got a new block

 

[limblines]

Re: Water leak around spark plug

Pretty easy fix remove the plugs, take out the bolts holding the plate on and there will be a gasket there. GO to your Merc store get the gasket you need you may want to take your old one with you. Clean all the old gasket off make sure both surfaces are clean and re-install. Should be ready to go.