Re: water passage crack
I had a 77 115 that had a 1" wide chunk of metal pushed out on the bottom of one of the water jackets right where it meets the head. Apparently the previous owner did not properly winterize it and the water froze and cracked the water jacket fairly severely. I took it to the mechanic and was told that the motor was junk, there is no way to fix it.
I recalled an old trick I learned back in middle school GMR working on lawn mower engines with cracked blocks...J-B Weld
Mind you the water jacket is under very little pressure, it isn?t like the combustion chamber, I think it is maybe 5 PSI
Here is how I fixed mine:
1) Order new head gasket
2) Remove head ( once the head is off don?t remove those rubber tubes around the inside of the water jacket, they are for a very important purpose, if you need to remove one to make the repairs make sure you put it back where you found it)
3) Trim the motor to where you can get at the inside of the crack easiest
4) Clean cracked area with acetone meticulously from both sides (inside and out). Use a dentist tool if needed to get down into the crack but be careful not to make it worse.
5) Put a piece of duct tape on the under side of the crack making sure it is as close to the metal as possible
6) Apply J-B Weld liberally from the inside but don?t apply so much that it will block the flow of water, again use the dentist tool to push the J-B Weld down into the crack
7) Trim the motor all the way down and let the J-B Weld seep down into the crack
8) Remove any excess that would potentially black the flow of water
9) Allow to cure for 24 hrs in HOT sun or under a heat lamp
10) Remove any old gasket material from the head and the block with a razor blade and fine sand paper
11) put the head back on, make sure to use the factory torque sequence and torque to proper ft/lbs per manual
