thanks for the reply. The fan and crankshaft did not turn when being pulled in gear .I will try to see if the the clutch turns when being pulled in gear. Yes hopfully it the clutch or flywheel. It would not turn over at all with the pony motor , it would just bog it down. I did not want to do this too much.

Yes, get the clutch inspection cover off and bar things over in and out of gear and with and without clutch engaged and check what moves and what doesn't.

I bought a D2-5u on new years day. Hauled it home yo the Cat Night Shop. The pony wouldn't run, and the main was locked up. Clean gas, new plugs, and fixed the plug wires.....had the pony purring. With the compression controll in the start position the pony would not turn the engine over, so to speak. The fan-crank would just start to move, then stop. We pulled the injectors, and turned over the main with the pony. Everyone standing close by was soaked with water that fiiled the cylinders. Water will not compress. It will just lock up an engine. We reinstalled the injectors. The main fired off with ease. I have had no problems with the cat since. I assumed that the cat was parked with no cover over the exhaust and rain water got in the cylinders. It was in too long as the long term damage was not there.

When you said the water was down a little, it got me wondering about water lock. With your last post about pulling it though, I'm lost. Was the clutch snapped in? If it was, must be a broken crank or something in the clutch or drive train locking everything up.

What about coolant leaking into the Cylinders.

I have had corrosion problems around the injectors before that ate a hole where the O-Rings go.

I had one of the two piece pistons unscrew on my D4 7U and it did not lock the engine. It did send a million little pieces of aluminum out the exhaust. I suppose it would be possible for the top half of the piston to unscrew and stop the engine. under the right load and rpms. I hate the idea of dragging a locked up engine around. If you have a leaking head gasket and one of the cylinders is full of antifreeze it would be hard to clear out without taking the head off. I doubt that there is any problem with the clutch. I would think the two piece pistons could be a likely problem as the dozer ran well before it locked up. This is just my two cents worth. Hope you find out the problem soon.

My bad, now that you mention it I know I had put it in gear but I dont think that I pulled back on the clutch in other words It was in gear but not engaged, oops. Tomarrow I will pull it from behind with the tractor in gear and engagedand see if it just drags which is my guess is what will happen.
Then I will test for water lock by disconnecting the injectors and try starting the big motor and see what happens. Any input is welcome Thanks

Just to clarify, do not just disconnect the injectors, remove them. You are really asking to bend something expensive by trying to crank a locked engine in any way.

HOWEVER- Speaking of locked, I have a pertinent question for Glen, OM, others-

Do you think it is possible to hydrolock a running engine?

A) It seems like it would be difficult to get enough water into the cylinder in one half revolution (1/30th of a second)* to cause a problem.

Even if the above happened the reciprocal mass (have you seen a Cat flywheel?!) would cause an immediate and catastrophic failure, not just a lock.

Rebuttals?

CS

*at 900 RPM each rev is 1/15 of a second. The compression stroke (no valves open) is 1/2 rev.

I agree, not likely to hydraulic lock, unless you drowned the engine, short of that, I would expect to seize the engine from lubrication problems/cylinder washdown, but not hydraulic lock it.

I've never seen a tear down of a drowned engine, (running when it went down), but I would expect a bent rod(s) at a minimum.

Hi Carl,
Would agree.....I'm not buying the running hydraulic lock theory either:rolleyes:
Sounds more like a mechanical or lube related issue to me.

Digdeep, I would not advise trying to drag the machine to turn over the engine. You risk doing further damage with that kind of force. I would try turning over the engine with a bar on the flywheel. Just to be safe.
When the engine quit did it make a lot of noise? If a piston let loose the clatter would be noticeable. Was the engine laboring hard when it stopped? that could indicate loss of lubrication. With out a working guage, would be hard to tell.
If the engine just quit and coasted to a stop might indicate a failure in the fuelpump or pump drive mechanism. I am not familiar with this machine, but a sheared key or broken gear could cause the "putt, putt then stop" senario.
The running engine could not hydrolock that fast. And water in the cylinders would show some serious smoke out the exhaust. Go slow and be gentle until you find the problem. Good luck, Jim.