Locked motor

[Frank K.]

Will pouring Marvel Mystery oil into spark plug openings free motor. Crankshaft will not turn by hand. Thanks any suggestions?

[Joe R.]

Re: Locked motor

Well it could but I doubt it. Looks like you will be looking at the inside of the motor soon. Why do you suppose it is locked up?

Water? Rust? Something broken?

JR

[Jeffrey S.]

Re: Locked motor

I have seen this method work in the past, but , if the pistons are stuck in the bores the rings are probably stuck in the piston groves so disassembly is in order in any event. I would bite the bullet and remove the intake and heads and message it from there. Hope this helps Jeff

[Dick W.]

Re: Locked motor

MMO works some of the time. Just give it several days to soak. Rock the crankshaft back and forth to break it loose.

[Frank K.]

Re: Locked motor

What do you mean rock the crankshaft back and forth?

[Bob R.]

Re: Locked motor

Try to turn the crank right then try left and so on and so on until it breaks loose.

[Chris S.]

Re: Locked motor

What do you mean rock the crankshaft back and forth?

socket on the crankshaft bolt and a long breaker bar

[Larry M.]

Re: Locked motor

If the engine is in a car, make sure the transmission is in neutral before trying to rock or turn the crank by hand.

[Frank K.]

Re: Locked motor

Great info from all members! Thanks every one.

[Michael W.]

Re: Locked motor

socket on the crankshaft bolt and a long breaker bar

That could easily shear the bolt, compounding the problems.

[Chris S.]

Re: Locked motor

That could easily shear the bolt, compounding the problems.

with some common sense ...... I have done it hundreds of times and never sheared a bolt.... It works

[Patrick B.]

Re: Locked motor

Comp Cams and others make a crank socket that uses the crank key and thus allows as much torque as possible in both directions. Use can use a big breaker bar or even an impact wrench with one of the fairly cheap tools.

[Michael W.]

Re: Locked motor

with some common sense ...... I have done it hundreds of times and never sheared a bolt.... It works

Common sense is an optional extra with many hand tools

[Ronald R.]

Re: Locked motor

Make sure all spark plugs out could be hydro lock

[Darryl D.]

Re: Locked motor

I think PB Blaster would work better.