Freeze Plug Size

[ThomasHill]

I have the Merc 120hp GM Block. 1977 model which I believe makes it a model one. I need to replace the freeze plugs. One has popped out completely and the other I can feel about 1/4 inch pushed out from the block. My question is what size. Looks like I have a choice between 1 5/8 inches and 1 3/4 inches.
Jack

 

[Don S]

Re: Freeze Plug Size

Read this first.

http://forums.iboats.com/showthread.php?t=192525

 

[ThomasHill]

Re: Freeze Plug Size

Thanks Don, I stand corrected. When I bought the boat they told me they didn't winterize it. I looked the engine over and saw no signs of a cracked block. Sunday, the owner of a marine shop came up to look at and purchase a couple OMC stern drives I had. He looked the engine over as well and mentioned the spots where the block will crack. He's the one that discovered the core plugs had been pushed out. He also discovered what looks like a crack on the exhaust manifold right on an edge. He felt JB weld would handle it. I was going to put the core plugs back in, hook it up to water and see if I see any leaks. If not, try to start the engine and see what happens.