Freeing a stuck engine

Question:

What is the best product and method to free up a stuck engine? I have a 327 cid V-8 in a 1966 Chevy that has been stored inside for 8-10 years. The car ran at the time it was parked. I was hoping to find a product to spray in the plug holes and let set for a time, instead of tearing the engine apart.

Answer:

Since the engine was running when the car was parked, it’s safe to assume that the engine’s failure to turn now is not due to a broken connecting rod or other internal damage.

In all likelihood, one or more of the piston rings is probably stuck to a cylinder wall because of rust. Remove all of the spark plugs and squirt a generous amount of Marvel Mystery Oil or an equivalent penetrating oil into the holes. Do this a couple of times per day for several days.

Use a socket and ratchet on the harmonic balancer bolt to try to break the engine free. If it doesn’t readily break free, try alternative turning of the balancer bolt clockwise and counter-clockwise. If you can’t break the engine free, your best course of action is to disassemble it.

If the rings are so severely rusted to the cylinder walls that you can’t free them up by applying a reasonable force to the balancer bolt then the chances are good that you’ll break rings and/or pistons if you apply enough force.