Farmall M transmission locked up?

[js2318]

I was blading a driveway last summer, when I heard a grinding noise at which time transmission appears to have locked up and killed the engine.

With clutch pushed in, tractor will start and it can be rolled/towed. Letting out on clutch will kill engine and lock up drivetrain. I pulled shift lever and verified it is not stuck between two gears, and it acts like I can still shift through all gears freely.

Pulling the top cover looks to be very time consuming and painful - anything else that could or should be checked before tearing everything apart? Thoughts on the potential issue?

thanks.

 

[used red MN]

I was blading a driveway last summer, when I heard a grinding noise at which time transmission appears to have locked up and killed the engine.

With clutch pushed in, tractor will start and it can be rolled/towed. Letting out on clutch will kill engine and lock up drivetrain. I pulled shift lever and verified it is not stuck between two gears, and it acts like I can still shift through all gears freely.

Pulling the top cover looks to be very time consuming and painful - anything else that could or should be checked before tearing everything apart? Thoughts on the potential issue?

thanks.

Hello js, welcome to YT or I should say welcome back since you posted about this in July of ‘24. I would assume that the tractor is towable in neutral only? I suppose by your description with the engine off with the transmission in any gear it will still be locked an unable to be towed even with the clutch pushed down, again meaning it is only moveable or towable in neutral? Up under the gas tank your tractor will either have a belt pulley drive or a block off plate where a BP drive would go. Remove that and see what you can see in there, most of the transmission can be seen under there.
Your description suggests something is locking one of the following, the input bearing or the what I call the “constant running gear set” that turns the lower transmission shaft or one of the bearings for the lower shaft has seized.
Here is a link to the transmission breakdown CNHI Farmall M trans diagram
Number 19 is the BP block off plate, numbers 40 and 65 are the constant running gear set.
When this happened do you know if the transmission had plenty of gear lube in it?

 

[js2318]

would assume that the tractor is towable in neutral only? I suppose by your description with the engine off with the transmission in any gear it will still be locked an unable to be towed even with the clutch pushed down, again meaning it is only moveable or towable in neutral?
-with clutch pushed in, I can move regardless of if in gear or not. With clutch not pushed in, it is locked up whether in gear or not.

Up under the gas tank your tractor will either have a belt pulley drive or a block off plate where a BP drive would go.

-there is aftermarket power steering that I am pretty sure sits on top of that plate. Will have to double check the next time I am there.

 

[wh]

Sounds more like problem at clutch. If tractor rolls free with clutch in, gears are not locked. Had the front pilot bearing go out once in an H. Locked it instantly. It would not roll period.

 

[BarnyardEngineering]

Stalls/won't roll in any gear or neutral with the clutch pedal out, but runs/will roll with the clutch pedal pushed in? Honestly I don't see how that's possible.

What the clutch does is release the fingers on the pressure plate, allowing the disc to spin freely.

When the tractor is rolling in any gear, the clutch disc is spinning, so everything from there back is okay.

When the tractor is running, the flywheel and pressure plate are spinning, so everything from there forward is okay.

There is simply no combination of problems in the flywheel, pressure plate, clutch disc, transmission input shaft that would cause what you describe.

I'm not saying you're lying, but perhaps you're mis-remembering something, or making assumptions/drawing conclusions based on incomplete information?

 

[Jim Becker]

Stalls/won't roll in any gear or neutral with the clutch pedal out, but runs/will roll with the clutch pedal pushed in? Honestly I don't see how that's possible.

What the clutch does is release the fingers on the pressure plate, allowing the disc to spin freely.

When the tractor is rolling in any gear, the clutch disc is spinning, so everything from there back is okay.

When the tractor is running, the flywheel and pressure plate are spinning, so everything from there forward is okay.

There is simply no combination of problems in the flywheel, pressure plate, clutch disc, transmission input shaft that would cause what you describe.

I'm not saying you're lying, but perhaps you're mis-remembering something, or making assumptions/drawing conclusions based on incomplete information?

I'm not sure this is exactly what he is trying to say. The original post says: "With clutch pushed in, tractor will start and it can be rolled/towed. Letting out on clutch will kill engine and lock up drivetrain."

It isn't clear to me it should be interpreted as being able to roll/tow while the transmission is in gear, nor that pushing the clutch has any direct bearing on rolling/towing. I read those statements as consistent with something jamming the lower transmission shaft, keeping that shaft from moving. An example might be a bearing failure that produced a foreign object that is now jammed in the constant mesh gears.

In any case, the OP needs to clarify exactly what his symptoms are.

 

[D Slater]

I was blading a driveway last summer, when I heard a grinding noise at which time transmission appears to have locked up and killed the engine.

With clutch pushed in, tractor will start and it can be rolled/towed. Letting out on clutch will kill engine and lock up drivetrain. I pulled shift lever and verified it is not stuck between two gears, and it acts like I can still shift through all gears freely.

Pulling the top cover looks to be very time consuming and painful - anything else that could or should be checked before tearing everything apart? Thoughts on the potential issue?

thanks.

If rolls with clutch pedal depressed and shifter in neutral the countershaft could be locked. Check hydraulic unit in center housing for locked up and for something jammed at input shaft or between it and constant mesh gear. With clutch disengaged the input shaft can sit still and tractor still roll in neutral because counter shaft doesn't need to turn. Might try engaging PTO and see if shaft will rock back and forth to dislodge a broke piece lodged between gears. Was typing when post above was put on and didn't see until I posted?

 

[wh]

If constant mesh gear is locked by bearing failure or whatever, then releasing clutch would not let tractor roll. If releasing clutch allows tractor to roll and engaging clutch stalls tractor then it has to be forward of transmission. Or he has facts wrong.

 

[Jim Becker]

If constant mesh gear is locked by bearing failure or whatever, then releasing clutch would not let tractor roll. If releasing clutch allows tractor to roll and engaging clutch stalls tractor then it has to be forward of transmission. Or he has facts wrong.

This all comes down to how you parse the OP's sentence "With clutch pushed in, tractor will start and it can be rolled/towed." Does the part before the comma only apply to the part to the left of the "and" or does it also apply to the part following the "and".

You are reading that sentence as:
"With clutch pushed in, tractor will start. With clutch pushed in it can be rolled/towed."

He may have intended the seemingly more probable symptoms as:
"With clutch pushed in, tractor will start. It can be rolled/towed."

OP still needs to clarify before anyone can provide more suggestions that will be known to apply.

 

[wh]

For sure need to clarify issue. If transmission is locked it cannot be rolled or towed without sliding wheels.

 

[D Slater]

For sure need to clarify issue. If transmission is locked it cannot be rolled or towed without sliding wheels.

If input shaft locked and clutch disengaged the engine can still turn because clutch plate is not turning with flywheel. If all speed gears are in neutral everything to top shaft in transmission can still turn and tractor roll because pilot bearing on end of transmission shaft can let the shaft turn with input shaft stopped.

 

[js2318]

let me try again.

With tractor running or not, the symptoms are the same.

-I can shift between all gears - shifts as smoothly as you would expect for a tractor that age. Don't have force or struggle to get it to shift.
-with the clutch pushed in and held, the tractor will move freely. You can push it, pull it, tow it, whatever. Doesn't matter if in gear or in neutral, it still moves freely
-letting go of the clutch binds something up and tractor will not move. Doesn't matter if in gear or in neutral, it does not move. When tractor running, letting go of clutch also kills engine.

in reading the posts, almost sounds like it is clutch related vs transmission?

 

[wh]

If tractor rolls with clutch released and in gear then transmission is not locked. You can access clutch thru the inspection plate underneath. Remove belly pump and you have a clear view of it.

 

[used red MN]

let me try again.

With tractor running or not, the symptoms are the same.

-I can shift between all gears - shifts as smoothly as you would expect for a tractor that age. Don't have force or struggle to get it to shift.
-with the clutch pushed in and held, the tractor will move freely. You can push it, pull it, tow it, whatever. Doesn't matter if in gear or in neutral, it still moves freely
-letting go of the clutch binds something up and tractor will not move. Doesn't matter if in gear or in neutral, it does not move. When tractor running, letting go of clutch also kills engine.

in reading the posts, almost sounds like it is clutch related vs transmission?

Okay my friend, you said this was last year yet you posted about it here on July 22, 2024. Which is two years ago. Have you messed with the tractor much say during last year or even recently this year? Your descriptions really don’t mesh together with what can mechanically happen in the transmission and clutch assemblies. We need you to go back out by the tractor and confirm that what you are saying is indeed happening or if the symptoms are a bit different. I suspect what you’ll find is that when the shifter is shifted into one of the gears, as in trying all 5 and reverse, you will find that in one of those gears it will move under power of the engine with the clutch let out and that shifting it into any other gear or possibly neutral will return it to stalling the engine when the clutch is let out. One possible scenario could be that the flex coupler has come apart and some how pieces of it are jamming the clutch extension input shaft and not allowing it to turn. It is number 28 in this linked parts diagram and the flex coupler is number 29. Messicks Farmall M parts diagram I’m using the Messicks version of the diagram because it has all the parts descriptions left in it. That shaft sets above the belly pump, it’s about a foot and a half long. If your tractor has a belly pump I am not to sure how well it can be seen when you pull the bottom access plate. That shaft connects to “transmission drive hub” 49 in the first diagram I linked above in reply 2. This possible scenario would not be able to explain why pushing the clutch would allow the transmission to be free, but weird things happen.

 

[mschwartz]

Does the tractor have a lift all pump ? Could something have failed or jammed up in the gears of the pump? Mike