801 motor problem - diagnosis help

polishdan · May 28, 2015

Was running fine 2 weeks ago, but had locked up. I jacked up one rear tire, pulled the plugs, and rocked in 5th gear. Motor turns smoothly only about 1/8 revolution, but binds up. Before I pull it down, I would like to get a few diagnosis opinions ..... timing chain, broken crank, bearings, rocker arm assembly, or whatever.
thanks

tractorguy2 · May 28, 2015

There is no timming chain on a 801. Could be a stuck valve or maybe even the hydraulic pump.

The hydraulic pump locked up on dad's 641.

souNdguy · May 28, 2015

lets rule out anything in the drivetrain.

with it clutched and plugs out, will it still only roll a bit by hand?

Does rotor move as engine moves?

polishdan · May 28, 2015

Can't roll it - frontloader bucket on ground. I think I can check the rotor by rocking the jacked up rear tire, but I'll have to get a friend over to watch the rotor.

polishdan · May 28, 2015

Thanks, I'll pull the pump and see if that makes a difference. The head was done not too long ago, but that doesn't rule out a dropped valve. DUH on the timing chain!

souNdguy · May 28, 2015

roll the engine! if the engine rolls over, it's AFT of the engine.

old · May 28, 2015

Pull the starter of to rule it out since they can some times jam in the flywheel ring gear and lock things up. As for the loader most have a brush guard on them that you can use a com-a-long on to raise the loader up off the ground so you can move the tractor. Also with the starter off you can use a pry bar to move the engine.

souNdguy · May 28, 2015

a simple stuck down valve won't be enough to do it mind you.. if it found the cyl, that's different.

polishdan · May 28, 2015

I already replaced the starter & solenoid. The motor does move about 1/8 of a revolution, so it is hanging up on something. I have a 1ton and chain to try (tow chain under bucket) & turn it over, but I would rather tear it down. Somebody suggested a frozen hydraulic pump as the culprit and I am going to pull that tomorrow.

polishdan · May 28, 2015

I jacked up one rear and can only turn the motor 1/8 to 1/4 turn while rocking the wheel in 5th. I have a hydraulic pump mounted to the front crank pully for my front end loader and can't get a socket on I to turn it over. Both rear wheels turn normally in and out of gear.

Ultradog MN · May 28, 2015

I would say you are going about this backwards.
Block the clutch down and with the spark plugs out, turn the engine over - either with a wrench on the front pully or pull the starter and roll the engine over via the ring gear.
You want to know if it's the engine that's locked up or the tranny/rear end that's locked.
Turning the engine over via the drive train does not tell you where it's binding up.

old · May 28, 2015

I would NEVER try pulling it to spin the engine over. Do so tends to cause things to break which would be bad. Do you have all the plugs out when you try to turn the engine over?? If you do not then pull then it may have a cylinder full of oil or coolant. Is the clutch held down to rule out a transmission problems??

old · May 28, 2015

Just because you replaced the start does not mean it is not the problem you could have a bad place on the ring gear and the starter drive is locked up on the gear gear and that will lock one up

dmbinva · May 28, 2015

AS others have said pull the starter and turn it with the clutch down.

polishdan · May 28, 2015

I totally agree. I am trying to eliminate causes without creating more problems. It ran fine 2 weeks ago when I last used it, so I don't want to go apesh*t on it. I pulled the plugs and dropped about an ounce of marvel oil down each cylinder. Somebody suggested the hydraulic pump is frozen, is that direct drive? It is jacked up on one rear, and the tire spins freely in neutral, and engages enough to move the fan for 1/8 or 1/4 of a rotation while rocking in 5th. Tomorrow, I am pulling the hydraulic pump.

polishdan · May 28, 2015

I have a front end loader with an auxiliary hydraulic pump on the crank pulley. I have no place to get a socket on the crank pulley. I may have to use a crow bar on the ring gear.

old · May 28, 2015

Block the clutch down and try to spin that tire. If it does not spin problem is in the transmission. If the fan belt is as tight as it should be and clutch locked down one should be able to turn the engine over by hand. That is how I check engines all the time for being locked up when I buy a fence row tractor which I do a lot

old · May 28, 2015

Pipe wrench in the hyd pump drive shaft works well BTDT on more then one. I have 2 fords with the hyd pump up front to run a loader so I know how they are set up and have owned them since 1982

polishdan · May 28, 2015

I'll try that, but I expect a few bloody knuckles.

old · May 28, 2015

Yes things are tight but glove help a whole lot and on many laying under it helps a lot more. That is also why I said if the fan belt is as tight as it should be and plug out one can turn the engine that way and if the clutch is blocked down that rules out a transmission problem. Or depending on which model you have even a PTO problem. If you have say an 851 if the bearings in the PTO shaft are locked up the engine will be locked up with out the clutch pedal down.

souNdguy · May 29, 2015

Never mind, you are wasting my time not reading my directions.

Good luck.

souNdguy · May 29, 2015

No dice. I've asked him twice to do this and still nada.

polishdan · May 31, 2015

Sorry bout not getting after this sooner, but I live in North East Texas, the tractor is outside, and the bass are wearing life jackets!
Plugs out, starter out, clutch blocked, and pipe wrench on aux hyd pump on the front crank pulley - results, still locked. The only thing external I can do is pull the main (or both) hydraulic pumps & see if that is binding ...... true or false?

Thanks for your help.

old · May 31, 2015

I would pull the hyd pump off that hooks to the crank shaft up front and try a pry bar on the flywheel ring gear. If no movement then you may have to drop the oil pan and see what is going on. May have a seized rod or main bearing

polishdan · May 31, 2015

can the main hydraulic pump seize it up? I think it runs off of the cam or ring gear, and I am suspect of it. Otherwise it is as you said. Fortunately, the inspection has all been gentle and I don't think I have compounded any problems.
The sun will be out for the next 5 days, so I hope to get this to a conclusion.
Thanks

old · May 31, 2015

Yes the main pump can lock up but not as likely as the front pump. And it does run off the cam

polishdan · May 31, 2015

I'll try the front first.

polishdan · Jun 1, 2015

Locked up! Pulled both hydro pumps and they spun freely. Bummer, now I'll tear it down. Thanks again for your help.

polishdan · Jul 6, 2015

Locked up 801 follow up. #4 cylinder sleeve dropped slightly (it was replaced about a year ago) & bound up rod. Extremely happy I didn't pull it off and do further damage. Many thanks to all that helped me.

801 motor problem - diagnosis help

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