Small Engines (Lawn Mowers, etc.): pull start on honda gx120, honda gx120, intensive job

Question
I have a greens mower with a GX120.  When i pull the pull start to try and crank the engine, and it will not pull, like its stuck.  I pulled off the crank assembly, and when its not attached to mower, i can freely pull the string out and it retracts properly, when i put it back on , it won't pull out.  What could be the problem?

Answer
Hey Mike,

I need some clarification, I think what your telling me is when you unbolt the rewind housing from the engine it works fine, but when its secured in place it does not work is this correct?

IF this is the case then i am afraid to say, but it sounds like your engine is locked up.  You can check this by trying to rotate the flywheel when the rewind assembly is removed.

If the engine is locked up, further investigation is needed to determine the extent of damage.  Usually it requires replacing the crankshaft and connecting rod.  It is a very labor intensive job

Dave