Hey guys I just got a 85 rx7 with a 12a. I was told it's been sitting for only a month but as of now the motor is sized up and I cannot rotate it at all. I have poured Marvel Mystery Oil in through the carb and the spark plug holes. I have also removed the spark plugs so that there is no compression. I have tried getting the engine to rotate in all of the gears by attaching my truck to it and pulling. (The clutch master cylinder is bad so I can't pop the clutch) I have used a breaker bar on the crank to try to rotate it that way to no avail. And I read that rotating it counter clockwise might help but it won't rotate at all counterclockwise. Any other suggestions short of pulling the motor and doing a rebuild?

 

You might try some SeaFoam. If a breaker bar wont budge it them it might have a lodged seal or seized barring.

 

I hear seafood is only a little better than Marvel Mystery Oil and alot more expensive? Is it really alot better?

 

Without knowing why the engine is not moving, any solution is going to be crap shoot. I know your hoping it's just carbon locked or maybe even rust. Whatever product you use must be able to dissolve carbon or even rust.

If what you have tried so far isn't working, I say the only solution is to tear the engine apart. Trying to force it might damage the rotor housing.

 

I've used seafoam quite a bit with success. As for the engine not turning, it could be that the eshaft bearing has gone bad. At this point the seals are probably stuck and bad too.