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?

The best way to remove the flywheels is to use channel locks to hold the flywheel itself. The colllets hold it tight enough to allow you to loosen the flywheel. I never did like the piston locks.

Another way I do it sometimes, is I take out the backplate and I stick a screwdriver on the crankshaft and I turn it, the bottom of the conrod locks the screwdriver and out comes the flywheel. I dont like this method either but sometimes its the only way. Its a lot cheaper to replace a conrod than a piston and sleeve.

I hydro lock my motors exclusivly and have had no problems. Could you be running a motor with a factory dished piston? It`s hard to figure how oil could do this by hand as the combustion pressure when the motor is running is much higher. By the way I use Permatex assembly lube on my motors as it is very thick and does an excellent job of locking the motor as well as lubing the parts untill the next time I run the motor.

This is the first time I did this because the flywheel was spinning on the crank. I used a socket wrench with a 12" handle, held the engine down on my work bench and really cranked on it. That was the only way to get it off. I tried the screwdriver in the crankcase but it started to scar the crankcase. The top of the piston looks concave with a couple of cracks in it.

Okay, sounds like it was like that already. Not a huge deal. The engine was a part of a complete car. Just wanted to Know if I had done the damage.