70 horse johnny threw a rod.

[rolmops]

I have been offered a late seventies Johnson 70hp outboard that threw a rod right through the crankcase.There is a hole about the size of a quarter in the crankcase.
I would have to replace or repair the crankcase,which does not seem to be a real big deal.I know that the engine did not set up, but what can I expect to find inside?Is the inside just a lot of destruction or is it usually a matter of the specific rod and maybe a reeds replacement?
Please, share your previous experience.
Oh by the way,If you have a late seventies crankcase in your junk pile,shoot me a PM, thank you.

 

[Silvertip]

Re: 70 horse johnny threw a rod.

First things first. Are you sure its a rod that let go and not a piston skirt that broke? If its a skirt that broke (rather common) you will need a piston, rings, and a gasket set as a minimum. Once you get the engine torn down, you will know more so don't buy parts until you've gone that far. I had a 60 that had a skirt break off and go through the crankcase. It was successfully welded. However, in your case, if it was a rod that broke, you may be looking at crankshaft damage, cylinder wall, and additional interior damage in the port areas, etc. If all of that has happened you would be best off by looking for a used or rebuilt power head. But, as I said, tear it down and see what you are dealing with.

 

[F_R]

Re: 70 horse johnny threw a rod.

The crankcase is not replaceable as a separate part. You have to do both cylinder and crankcase as a unit because they are matched.

Depending on exactly what let go, chances are about 90% that it had been getting water in the crankcase and that has destroyed the bearings, including the crankshaft. As said, you just gotta look.