Hi, I was wondering if any of you have ever damaged your piston while removing your flywheel nut using oil to hydro lock your engine? I got a used engine and the flywheel was spinning and the nut wouldn't budge. I lowered the piston and poured some oil into the cylinder, then removed the flywheel nut. When I dissasembled the engine, I noticed that the top of the piston looked like it was caved in. The sides of the piston and the sleeve looked almost brand new. Was there enough force to do this to the to of the piston?