First thing to do is determine why it is stuck. Do not assume a fried powerhead. Can you grab the flywheel and wiggle it back and forth at all? Often you can wiggle the flywheel some even if a rope pull feels like a solid stick. I’ve had this caused by seized lower unit gears, and related parts, even seized when in neutral, and have seen broken water pump impellers make them stick. If the flywheel will not move more than a barely detectable super small amount back and forth, it is likely one or both pistons are stuck. If so, determine if it’s one or both by sticking a long screwdriver in the spark plug hole until it touches the top of the piston – then try and rock the flywheel back and forth while keeping you other hand on the screwdriver to "feel" if the piston is moving at all. I recently had a 5-1/2 Evinrude, 1957, that I was able to determine had one piston stuck using this method. For stuck pistons/rings, as has been already said here, there are several methods of trying to free them up. I start by positioning the motor so the spark plug holes are straight up and then putting in a solvent that attacks corrosion like penetrating oil, liquid wrench, transmission fluid, or I’ve heard a lot of great things about Kroil freeing up pistons and rings. Once soaking, try to move the flywheel back and forth every few days – you may want to try moving it with a wrench on the flywheel nut just don’t put enough load on the wrench to unscrew the nut.
Dave
.
