DanG wrote:
Separate the motor and the compressor. Find out if one or both
have pistons stuck in the cylinders.

Remove spark plug(s) on the motor and the head of the compressor
if they are both stuck, generously apply Kroil or similar release
agent. Allow to sit, then attempt turning the flywheel again.
Look into getting a long cheater pipe to use on the flywheel(s)
without bending or hurting it.

Another common method of getting the rings loose is Coca-cola.


I've known folks to swear by Marvel Mystery Oil. Just pour generously into the cylinder
heads and let stand. Then use a cheater. You may wait days or weeks but it will
eventually penetrate it.