Engine locked on JD 301A

[domeman]

The engine was running fine. I shut it down normally. When I went to restart it a week later, as I was cranking it with the starter, the engine suddenly locked up with a "clunk" sound. There was no banging, clanging, pecking, pinging prior to the engine locking up. The flywheel cannot be moved, period. I have attempted to pry the flywheel loose using a short steel bar on the ring gear. Can't do it. I have pulled the plugs; all cylinders are empty. Therefore there is no hydraulic lock. Checked oil level - normal. Coolant level - normal. Hydraulic oil level - full (not overfilled). I pulled the starter. It is okay. I'm stumped. Any suggestions other than a stick of dynamite?

 

[jimmysisson]

I suppose you pulled the starter to get to the ring gear? (not starter lock, then). How about with clutch disengaged - will it turn then? No odd noises when you shut it off? Would be weird to spin a bearing or toss a rod at shutoff. Do you think anyone else could have done something to it in your absence (can't think what)?
You describe something pretty unusual, but hold the nitro.
Jim

 

[domeman]

With clutch disengaged, the engine is still locked. No noise at shutdown.
Domeman

 

[Hooked_on_HP]

Did you try turning the engine backwards. If you know any one with a bore scope I would be looking to see if something is on top of one of the pistons. You might want to take off the valve cover and look for a droped valve
Bill

 

[skyhook]

Pull the valve cover and then the oil pan.
Go from there, sounds like something let go.

 

[Zebrafive]

If pulling the valve cover and oil pan do not show what's wrong. Next pull the timing cover and see if the gears are jammed with something.