Thanks, guys. Keep it coming.
It may be too late (time frame in the water) but you have nothing to loose.
Turn the motor so the plug openings are upside down and rotate the crank/flywheel. Then after whatever water does come out, turn it back over so the plugs are straight up and fill the crankcase through each spark plug with engine oil. Doesn't matter what you use but fill it. The oil will move through the ports of the motor and into the crankcase. Don't turn the crank completely, but in small steps to expose any possible covered transfer ports and add oil as the level changes. Then turn it upside down again and let all the oil drain out. Rotate and keep changing the angles until it rotates freely with the plugs out and there is no oil left. This could take a couple of days but you should try to do it twice and take your time.
option #2 ........pull the power head and disassemble it, which is what I would do.
Two strokes depend on the oil in the fuel to lube the entire crank/rod assembly and that oil comes from the carb/fuel mixture. The cranks run on roller/ball bearings and there surfaces are fragile to saltwater. I would also suggest pulling the carb and giving it a good cleaning. filling the engine so that oil runs out both the intake and the exhaust may seem like alot of work and a huge mess but what are the other options other then a new motor.
If it happens to be a four stroke
4 stroke.......Drain the crankcase and flush with oil at least twice, Remove the valve cover and flush out the area and re-oil each rocker/cam lobe with assembly lube. Pull oil pump, and claean and ensure pressure relief valve is not corroded. Clean carb as above.
Don't forget the fuel lines and tank if there was one in the boat.
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