Re: Mercury ME5M locked up?
Most likely overheated and jammed a piston. Lucky it would down and didn't jam up at high speed. It got hotter and hotter as it ran and jammed slowly. No doubt the cylinder wall is scored a little. Rings may be cracked... I'm not familiar with the engine so we'll do better if you give us the serial number. I'm guessing that 2004 is a 4-stroke...??
Why the over heat?
No water circulating in the cooling system; puttering in the garage without water can burn up the water pump impeller; blockage in the water lines, bad thermostat.
If it's a 4-stroke, not enough oil in the sump. If it's a 2-stroke, too lean, not the right oil in the premix.
Worse case is a loose connecting rod on the crankshaft. It's possible, but not likely, the screws holding the connecting rod to the crank got loose and the piston wobbled for a while. Again, not likely. Just possible.
Start by removing the recoil starter. Be sure the starter isn't jammed up. Remove the spark plugs to relieve compression, then try to spin the crank with the flywheel. If it still does not turn, you're gonna have to tear it down and loosen the piston by hand.
With any luck, you'll be able to insert a wooden drift into the spark plug hole and tap the piston free. BE CAREFUL!!! Get another set of hands and apply torque to the flywheel (clockwise) as you LIGHTLY tap the stuck piston. You might get LUCKY.
J
