Overheated. won't start

[kcasper0315]

I have a 1979 Johnson 25 h.p. that recently overheated badly. I don't think i had the water pump copper line attached. Since the OH it is very hard to pull the starting cord and won't fire at all. I checked and it's not seized, but the top piston (2 stroke) is much darker than the bottom. I read to remove the plugs and see if that frees it up, it did. I replaced the plugs with new, but it is still having the same problems. I don't know where to go next.

 

[kbait]

Check compression first, if good, check spark with an open-air tester set to 7/16”.
If compression is poor, pull cylinder head and check head gasket, as overheats can slightly warp the head, causing gasket failure (check head for warpage before re-ass’y). If no spark, most likely cd box failure due to overheat.
Good luck!