New Holland 3930 flywheel won't turn

[pdschloss]

My 1990's New Holland 3930 won't start. For background, this is a weird 3930 where a prior owner replaced the deisel engine with a gas engine. Anyway, it has a new battery and power is getting everywhere it is supposed to be. The distributor rotor is not turning when I crank on the ignition. I took the starter off and have had it tested and it seems fine. When I try to manually turn the fly wheel that the starter attaches to, it doesn't budge. Any ideas what might be going on or what it might take to fix?

Thanks!
Pat

 

[ruffdog]

Maybe hydro-lock?

HL is when a fluid gets on top of the piston and fluids don't compress. If pushed too hard, you can break a piston or bend a rod. Pull the spark plugs and see if it can move by hand. If it can, crank it over. Is it gas or coolant?

 

[Texasmark]

How about some history. Possession, run time, uses, habits, last time it did if it did ever run...PO history of usage.....things like that to steer us in the right direction.

Also does pushing in the clutch allow you to roll the engine by hand? If so, with the clutch out and the tranny in N (both levers) can you roll it?

Hydro lock that PD mentioned could be caused by an open vertical muffler exhaust pipe whereby a sufficient quantity of water enters the combustion chamber and gets trapped. On that it all depends on how much and how many cylinders are affected. Usually you can attempt to rotate the engine by hand in both directions and one direction will allow you to expel the water, or if in any doubt pull the plugs if gas or injectors if diesel and see if it will roll then.

On a gas tractor, if you have a gravity feed tank and a leaking float valve in the carb, you can ingest gas that way. The 3930 has a gravity feed tank but the carb is probably up draft and the engine is OHV putting the intake ports above the block and it would be really hard to fill the cylinders with gas.....on diesel, no way.

 

[CalG]

"Cranking the starter" suggests you are getting some sort of "whirring" sounds that would indicate internal motion of the engine.
But No rotor spin and no flywheel spin suggest things are NOT moving.

It's a gas engine.

Pull the spark plugs. Look for fluid or RUST.

If it's rust, Tow the tractor while in high gear and let out the clutch to see if the stuck pistons will break free.

If fluid, leave the plugs out and crank with the starter.

If the fluid is WATER, you may have both issues.

An Aside:

I have a Fordson E27n, I got it some years ago (when I was a young man), and for a while, I ran around the country persuing work and raising a family. I left the tractor "with a friend".
I fianally settled in and went to retrieve the Fordson. It was a cold but sunny January day. The hand crank wouldn't budge the engine a bit. I went back to the tractor a few days later. We were having one of those "January Thaws", and I thought the warm air would ease the investigation and removal plans. Low and behold, The engine hand cranked over as free as could be.
Turned out, that the many years of sitting had condensed water into the crank case. Enough to freeze up on cold winter days and lock the crank throws solid. I put two and two together on the spot and loosened the sump drain just enough to allow the water to dribble out. When oil showed, the plug was put home again. A few sins with the handle, and that old gal was running right then and there, even after all those years. ;-)

Just a story to recall, but you might have something blocking the free movement of the crank or pistons. My money is on rust in one or more cylinders. But you need to look into it more.

 

[Texasmark]

I had some work done by a shade tree mechanic on a Ford one time and when he installed the clutch mechanism onto the flywheel, the bolts he used were too long. They stuck through the rear of the flywheel and jammed on the engine casting preventing the engine from turning. Don't know how you would verify that without a split.