Funny you should say that actually..
A good friend of mine had a look at my engine when it was still in the boat, and he thought it was the big end that had gone - don't ask me, I can only drive 'em
After getting the engine out of the boat and giving it a good coat of looking at, we found the problem - Shattered piston, with half of it sitting in the sump!!
Anyway, we now have replaced the piston, oh, and the snapped push rod and I now have one lovely little thumper again.
The engine seems to be fine, but I'm now awaiting for my friend to carry out some welding as the engine's only had two bearers to sit on, instead of the four. They were bolted to the engine but weren't fixed to the hull in anyway.
I'm getting there - only a full repaint and a fit out to be done now LOL.
Don't ya just love boating..