[mclamore]

I had to tear it down to re-sleeve one cylinder due to a cracked piston and broken ring. While inspecting the rods crankshaft bearings ect. I found that the bottom rod and the third one up had wear on the top sides and also the crankshaft had wear from the rods. None of the other rods or crank have any wear nor the bearing. The motor was getting plenty of oil nothing else looks bad. Anybody got any ideas I talked to a friend if mind that is a good outboard mech,he said he did not have a clue.

[rodbolt]

hello without looking at it I dont know. however if the bottom bearing is failing it will allow the crank to walk up and down. time for some careful inspections so it does not happen twice.

[Ray Neudecker]

How many hours are on it? Was the ring failure caused by extreme carbon deposits causing the ring to stick? It would take a close exam of the engine and components to really determine the cause.

[NEECAPRS]

mclamore,Along with looking very closely at everything, it seems like the pistons/rings for those cylinders should have something wrong with them to be forcing the crankpin end of the rod upward. This check should follow the check of the bottom bearing as rodbolt suggests. The shaft running too low on a (badly) failed bearing would give you that and maybe the broken piston you've found.