Farmall M Stops moving/PTO while mowing

Trevor H

Member
My 1944 Farmall M stops moving/pto while mowing.

This tractor is new to me I have only owned it a few months and this is the first time i have used it for any operation.

So far i have changed all fluids and filters
Did a valve adjustment
cleaned/rebuilt carb
Converted to a Delco 10SI Alt 1 wire
Rebuilt starter
Installed 3 point conversion with twin lift cylinders
and other general service items

I am using a JD 390 flail mower weighs approx 950 lbs

The tractor runs and drives great and i cant get it to act up while just driving the tractor. But when i shift the PTO into gear approx 5-10 minutes into mowing the tractor just stops moving and the pto stops spinning. the engine continues to runs fine.

If i disengage the pto and shift into neutral, push the clutch in a few times the tractor begins to operate normally again. I can the re engaged the PTO and mow for another 5-10 minutes before it happens again. The only thing that concerns me is that i cant get the tractor to duplicate the problem with out the PTO engaged

No change if i hold the PTO shift arm up....This seems like a clutch issue. I just cant figure out why the clutch would only act up while mowing and not during any other driving operation in any gear.

Any Ideas?
Thanks for your help.
 
During the time the tractor is not moving/pto engaged but not spinning. The clutch is fully released during this time.

You can shift the PTO in and out of gear with out grinding

You can also shift the transmission into neutral and into any gear with out grinding.
 
I'm sure no expert, but first thing that occurs to me is clutch adjustment. Has the clutch rod been adjusted properly? Second, hsa the pressure plate fingers been adjusted properly? [If at all possible; they might be too worn and relaxed to adjust.]
A 70 year-old tractor, things might be worn our.
 
I have checked adjustment of the clutch rod. Free
play at 3/4 - 1 inch

I have not attempted to adjust clutch fingers i
think I have to drop the belly pump to do that.

This M also has LIVE HYDRO if that makes a
difference.

I am not afraid to split the tractor and put a
clutch kit in it. I just dont want to do that and
it not fix the problem...As the tractor operates
great while not in PTO.
 
You need to determine if the drive shaft and countershaft are both turning when this happens. Problem is this can be dangerous. You have to take bottom cover off behind belly pump and when this happens find out if one or both are turning. Mount a mirror underneath so you can see the shafts while you are still in operating position to be able to safely control the tractor. This will tell you if clutch is problem or inside transmission.
 
Your problem is definately in the clutch. The M PTO is very simple. When you engage the PTO you are connecting the drive tube to the back of the trans countershaft.

With the belly pump out, the clutch disk and pressure plate can be removed from the bottom. Perhaps it got contaminated with oil or grease and is glazed over.
 
I plan on keeping this tractor for life.... Would you guys recommend splitting the tractor to service the clutch/ flywheel

Or can I remove the flywheel if the belly pump is removed?
 
I'd try hooking to the tractor to something tht pulls hard. Like an old junk car with no wheels. Or use the brakes to see if you can make the clutch slip without the PTO. That should answer your question but it does sound like a slipping clutch from what you describe.
 
If tractor has a belt pulley gear box, put it in gear when using the tractor. If it also stops turning its a clutch problem or something ahead of the transmission. If it doesn't stop turning it may be a retaining failure of constant mesh gear to countershaft. Although unlikely to start pulling again unless galling.
 
(quoted from post at 03:56:05 08/14/14) I plan on keeping this tractor for life.... Would you guys recommend splitting the tractor to service the clutch/ flywheel

Or can I remove the flywheel if the belly pump is removed?

The clutch can be serviced without splitting the tractor, but the belly pump must be dropped. The pressure plate and clutch disc can then be removed, but the flywheel WILL NOT fit through that opening. That flywheel is HEAVY. A normal guy would not be able to remove it from below, even if it did fit.
 
I mowed about 2 acres with it this am and I can duplicate the problem in 1 2 and 3rd gear. It does not have a pulley gear box so I can't do that test. Over the last 30 mins of mowing when it stops moving I can step on the clutch real quick and shift into neutral by the time the mower stops spinning I can go back into gear with out even dis engaging the pto and continue on.

I have do a lot of clutches in cars and trucks. Never done one in a tractor. I would assume that splitting the tractor so I can surface the flywheel is the best way to go.

Or would you just drop the pump and change only the clutch?
Thanks for all the comments I appreciate the help!!!!
 

Are you saying that the mower keeps on running when the tractor quits moving????

Do you have an M&W on that thing?
 
This tractor does not have a hand clutch. I am just getting
used to it stopping now. If I act fast I can just push in the clutch
and shift the trans into neutral about 20 seconds later the
mower stops spinning I can shift back into what ever gear I
want let off the clutch and the tractor and mower start
operating normally. If I don't act fast and push the clutch in
immediately . I have to shift into neutral and disengage the pto
wait 30 seconds and then everything works as it should again.

This afternoon I am going to hook it to a heavy trailer and see
if I can get it to act up pulling a heavy load.
 
Yes, as usual it's best to re-surface flywheel. It's a stepped flywheel so you'll need a knowledgable shop to grind it.

First drop the belly pump so you can see what's going on.
 
Another idea is a loose coupler flange on the input to the trans from the clutch coupling "joint". It is splined, and if it were loose, the clutch shaft and coupler could move forward enough to disengage, stopping everything in the trans, including the PTO.
It would require the removal of the belly pump/reservoir to access the input shaft assembly. If the clutch will allow you to operate the tractor in road gear with no slipping, I doubt the clutch is the issue. Jim
 
You got a picture of that? Im lost as I dont recall any splines being on that shaft at all, if you want to call it a shaft. Best I can remember is the yoke was connected directly to the coupler, yoke bolted to the shaft for the constant mesh gear with one bolt and a concave flat washer, with a key to keep it from spinning on the CM shaft.

Regardless, sounds like a clutch issue to me.
 
(quoted from post at 23:21:46 08/13/14) I have checked adjustment of the clutch rod. Free
play at 3/4 - 1 inch

Is the pedal back against the platform of staying ahead a bit???
 
No the mower/pto and the tractor both stop when the problem
happens.

Over the next day or so I am going to pull the belly pump And
take a look. I would consider my self an accomplished
mechanic and to me this just does not feel like the clutch is
slipping. It will run in 5 gear with a decent load behind it. If I
drop the clutch it will pull the front tires off the ground. This
does not feel like slipping it feels like everything just gets
disconnected. I can't feel it slip at all.
 
Inside the trans where it connects to the input shaft. (might be a key)
If the yoke center bolt was loose or gone it could work out and stop driving the internals. Jim
 
(quoted from post at 15:59:26 08/14/14) Inside the trans where it connects to the input shaft. (might be a key)
If the yoke center bolt was loose or gone it could work out and stop driving the internals. Jim

I think is a key, had mine off before to change the seal too.

If the flex coupler is good things should not have too much movement in there but it may be worn or have broken or missing bolts also.
 
(quoted from post at 16:42:14 08/14/14) Yep, woodruff key. Im on the same page now. I still think its a clutch problem!

That is why I asked if the pedal was back all the way. (no answer)

When worn out the throwout binds up from a worn clutch and the pedal will not return. (causing lack of pressure on the disc)

Some pics of the linkage would help too. The rod may shortened all the way at this point.

Also his comment about the PTO makes no sense as it drives off the counter-shaft.
 
Having re-read all of it, Im confused!!! It sounds
to me like hes pushing the pedal down, and
everything is stopping like its suppose to, but hes
not pushing the clutch pedal down, am I right,
Trevor? Anytime the clutch pedal is pushed down, the
PTO will stop, so it has to be something from the
clutch back to the trans.
 
I'm not sure what the cause is but one of your posts sounds like you need an overrunning coupler on your pto, do you have one?
 
The clutch pedal is all the way back to the plate at all times. The linkage rod is close to max length for adjustment but the pedal free play is about 3/4 of and inch.

I am well versed on how this tractor/pto works. When I am mowing everything it working like It should, all of a sudden everything stops....tractor stops moving and pto stops spinning.... like the clutch was pushed. I can't feel it slip and no unusual noises/ vibrations. If I then push in the clutch shift into neutral AND let off the clutch THEN push the clutch and shift back into gear the tractor and pto start operating as usual again.
 
The clutch feels good at all times... The free play and pressure
feel normal the linkage is well greased and adjusted properly.
 
This post is exactly correct. Everything stops just like you pushed the clutch all the way in but I did not the clutch is all the way back to the plate and nothing is happening. At this point if I push in the clutch and shift to neutral let the clutch back out I can then push the clutch back down shift back into gear and let off the clutch and everything operates like normal again for approx 10 minutes then I happens again.
 
(quoted from post at 16:01:54 08/15/14) This post is exactly correct. Everything stops just like you pushed the clutch all the way in but I did not the clutch is all the way back to the plate and nothing is happening. At this point if I push in the clutch and shift to neutral let the clutch back out I can then push the clutch back down shift back into gear and let off the clutch and everything operates like normal again for approx 10 minutes then I happens again.

After reading through all the replies, I think I have to agree with guys that mentioned problems with the transmission input shaft, or maybe even an internal transmission problem.
 
Well, one thing is for sure, you don't have a "clutch problem". I think you're going to find either a transmission pilot bearing failing allowing the input shaft mowing forward & back and letting the constant mesh gears get out of engagement, or the lower transmission shaft getting loose in the bearings in the trans. The M had a splined lower shaft where the H has a keyway the full length of the shaft, the gears can move around and get into & out of alignment.

I'd pull the plate off where the belt pulley would attach and push/pull/pry around on various gears and I think you'll find your problem. I would think you're risking greater damage to your M by continuing to run it.
 
I forgot I had to go out of town this weekend... On Tuesday I will pull the pump and others plates to see what's going on...

I will post pictures of anything that looks out of wack. And I am sure will need some more advise. Thanks for you help everyone!!!!!
 
The reason I said to use a mirror to look at the shafts is due to the fact I don't want to tell him to crawl underneath when this stoppage occurs. He may not have it in neutral and get run over. If I was there I would simply take that lower cover off behind belly pump and look at the shafts. Then you will know problem is inside or outside. I have seen the counter shaft break in a super M one time and it did all kinds of things. It broke inside the gear so some things worked and others didn't. Fact is learned a valuable lesson because I pulled cover and could not find a thing wrong. Put it back together and then found out the gear on shaft would move back far enough to press on the cross shaft brake pedal operates and brake lever would bind. Had to dig in deeper to find a problem.
 
When the tractor stops moving and the PTO quits, try shifting into 5th gear without touching the clutch or PTO shift. If it grinds and the PTO is still not working the problem is internal to the transmission lower shaft. If it goes into 5th without grinding the problem is between the clutch and transmission.
 
Why don't you guys think it's the clutch?

It sure sounds like the clutch to me.

If it were internal to the transmission there would be some sort of clatter or grinding or ka-BANG!, and it would happen exactly ONCE.

The clutch is slipping all the time, gets hot, and won't hold anymore. Give it a few minutes to cool and it will hold again for a while. Of course it will run longer from cold because it takes time for heat to build up. Just sitting there for 5-10 minutes only lets some of the heat dissipate.

It doesn't do it when you're not mowing because the mower puts a tremendous load on the drivetrain!

There's no way to know for sure what's wrong until you start taking things apart. You don't have X-ray vision. We don't have X-ray vision. Time to get the wrenches out and get busy.

My recommendation is that you drop the belly pump and pull the clutch through the bottom. If the clutch is indeed shot, you can then split the tractor and resurface the flywheel if you think it's necessary. Otherwise, you haven't put a whole lot of effort into tearing the tractor apart unnecessarily.
 
(quoted from post at 05:26:29 08/18/14) Why don't you guys think it's the clutch?

It sure sounds like the clutch to me.

If it were internal to the transmission there would be some sort of clatter or grinding or ka-BANG!, and it would happen exactly ONCE.

The clutch is slipping all the time, gets hot, and won't hold anymore. Give it a few minutes to cool and it will hold again for a while. Of course it will run longer from cold because it takes time for heat to build up. Just sitting there for 5-10 minutes only lets some of the heat dissipate.

It doesn't do it when you're not mowing because the mower puts a tremendous load on the drivetrain!

There's no way to know for sure what's wrong until you start taking things apart. You don't have X-ray vision. We don't have X-ray vision. Time to get the wrenches out and get busy.

My recommendation is that you drop the belly pump and pull the clutch through the bottom. If the clutch is indeed shot, you can then split the tractor and resurface the flywheel if you think it's necessary. Otherwise, you haven't put a whole lot of effort into tearing the tractor apart unnecessarily.

No, there would not necessarily be a bang, or pop, or any noise at all. I had an H not too long ago that would not stay in 3rd gear. I could shift into third, and just as quick as I let the clutch up, it came out of third gear. The tractor might have moved an inch or two, but that was all. No bang, pop, crunch, or grinding of any kind.
 
Yeah, but this is not that.

The tractor is not coming out of gear. It is just stopping in its tracks if I read things correctly. The OP can shift into any gear and it won't go.

I just don't see how holding the clutch in would let something that's physically come apart move back together and then only hold again for a few minutes... It sounds more like something is "cooling off" to me. The only thing in an M that could be cooling off like that is the clutch.

Again, it's not a huge deal to drop the belly pump and pull the clutch to actually SEE what's going on. If it's further down the line all that has to come out anyway... So no work lost.
 
The whole key here is he said he can shift into any gear and that to me means all gears including 5th. Now I don't really know if he has tried fifth or not but that would sure be a telling situation if we knew. I never like tearing something apart that is inherently this simple to diagnose by looking at a couple things that are or are not happening.
 
(quoted from post at 07:08:53 08/18/14) Yeah, but this is not that.

The tractor is not coming out of gear. It is just stopping in its tracks if I read things correctly. The OP can shift into any gear and it won't go.

I just don't see how holding the clutch in would let something that's physically come apart move back together and then only hold again for a few minutes... It sounds more like something is "cooling off" to me. The only thing in an M that could be cooling off like that is the clutch.

Again, it's not a huge deal to drop the belly pump and pull the clutch to actually SEE what's going on. If it's further down the line all that has to come out anyway... So no work lost.

If I weren't in the process of dismantling an H transmission, I might agree with you. The main input shaft has a gear on it that meshes with another gear internally, and that is what drives the whole thing. If one or both of those gears is damaged and chewed up, as mine is, it is very possible for those two gears to slip.
 
No offense but we already know what it does or does not do at this point. There are only two options:

1. Start tearing into it to find out what's really wrong.
2. Park the tractor in the tall weeds out back where you can't see it and it won't remind you of its failure.
 
(quoted from post at 16:12:00 08/18/14) No offense but we already know what it does or does not do at this point. There are only two options:

1. Start tearing into it to find out what's really wrong.
2. Park the tractor in the tall weeds out back where you can't see it and it won't remind you of its failure.

We know the transmission counter shaft stops turning but we do not know for sure in the input shaft also stops. Until that is determined we don't know if the problem is in the clutch or in the transmission.
 
Ok got the belly pump out.

There was some slack in the 4 bolt clutch joint. All the bolts were tight just some side to side play.

The trans input shaft still has the keyway/key so not an issue there.

I had to call it quits there. I will have the clutch out bright and early tomorrow morning to check it out.

With the pump out I did notice that when the clutch pedal is pushed all the way down it only moves the throw out bearing approx 3/8 of an inch. It does release the clutch disk though.


I also found a fine thread bolt approx 3/8 diameter in the small hole just below the rear main seal behind the flywheel. I can't get the bolt out of the hole I can only assume this is a rear main seal cover bolt??????

I am most likely going to split the tractor to find out where the bolt came from/ surface flywheel and clutch work.
 
Pulled the clutch this am did not find anything broke or out of place. The pressure plate looks like it is in rough shape the disk looked much newer. I am going to put a clutch kit in it and see if that fixes the problems.
 
Alright.... I have installed a new clutch and pressure plate through the belly pump hole...the tractor still acts the same way as before. If I try and shift into 5 gear after the tractor stops moving/mowing it grinds..... I can shift 1-4 with out any issue

Also looked at the counter shaft it is not spinning during the time the tractor is acting up.

So now we know the issue is inside the transmission. Where should I be looking to find the problem...


Thanks again !!!!!!
 
On an M there's really only one place to look: In the transmission!

It's a very simple tractor with a very simple design. You're going to have to remove the top cover to fix it regardless so once you remove the top cover you should be able to see what's wrong plain as day.
 

Sounds like the constant mesh gear on the counter shaft may have stripped the keyway. But I don't understand how it will start pulling again. Unless its not on a hard pull and the press of gear on the shaft is still tight. You say it grinds when trying 5th. Is this with the clutch released or disengaged? If you can push the clutch pedal down and shift to 5th and it pulls it would be a bottom shaft problem. Would think if the input shaft and constant mesh gear have teeth missing or bad bearings moving the gears apart you would hear bad noises when it stops moving.
One other possibility I can think of. Does the tractor have a aftermarket 9 speed transmission or had one partially removed?
 
After the tractor stops mowing/moving I try and put it into 5th gear with the clutch NOT depressed it grinds. If I depress the clutch it will slide into 5th as normal and the tractor will move/mow. From this point I can depress the clutch again go to any gear I choose and it will operate normally until the problem happens again.

Factory 5 speed trans
 
It sounds like the problem is going to be on the lower transmission shaft. Can this shaft be accessed/ fixed with the top plate removed or will splitting the tractor be necessary???

Thanks for the help!!!!
 
Maybe able to see what the problem is through the belt pulley gear box opening, but if the constant mesh gear (front gear on the lower shaft) is bad or anything on the bottom like a key or keyway failure or broken shaft. Transmission top has to come off and enough disassembly under tractor up through the center housing or a transmission split to remove the transmission input shaft with housing.
Normal for gears to grind when trying to shift into 5th without depressing the clutch pedal. If it grinds going to 5th when the PTO stops turning that indicates the transmission input shaft is still turning. If its turning the failure is narrowed to the input gear teeth driving the constant mesh gear or constant mesh gear or on lower shaft as mentioned above.
 
Yes it sure sounds like the failure is going to be on the lower shaft....one thing I forgot to mention is that when I drained the trans/diff oil while putting in the new seals on the counter shaft and main trans shaft. There was a large amount of water in the gear box... I would estimate at least 5 gallons. The insides don't look rusty but I would bet this tractor sat for a long time out side and water got into it and just sat on the lower transmission shaft.

I would have to assume this is what has cause this failure.

The thing that puzzles me is how that amount of water accumulated in the trans. It looks pretty well sealed up. I guess 40 years of water seeping through to top plate bolt holes?????

This tractor will never be stored outside while I own it so this won't be an issue again.

I will get busy popping off the top plate and let you know what I find
 
(quoted from post at 06:02:01 09/06/14) Yes it sure sounds like the failure is going to be on the lower shaft....one thing I forgot to mention is that when I drained the trans/diff oil while putting in the new seals on the counter shaft and main trans shaft. There was a large amount of water in the gear box... I would estimate at least 5 gallons. The insides don't look rusty but I would bet this tractor sat for a long time out side and water got into it and just sat on the lower transmission shaft.

I would have to assume this is what has cause this failure.

The thing that puzzles me is how that amount of water accumulated in the trans. It looks pretty well sealed up. I guess 40 years of water seeping through to top plate bolt holes?????

This tractor will never be stored outside while I own it so this won't be an issue again.

I will get busy popping off the top plate and let you know what I find

I just recently dismantled a Farmall H. I was very surprised when I removed the trans top cover. About 5 gallons of water and NO oil of any kind. Surprisingly, the inside of the housing looked almost brand new. NO rust, and the gears, while being almost entirely chewed up and worn out, had almost no rust anywhere. The bearings even came out in very good condition. With just a little cleaning up, they will be good as new.

For what it's worth, I think you can remove the bottom shaft without splitting the tractor, but the top shaft will have to come out first, and it will be easier if the differential is removed also.
 
To remove the transmission counter shaft:

Remove the LiftAll pump assembly.

Remove the drive shaft coupler and slide the clutch shaft forward.

Remove the cap screw and washer from the transmission input shaft and remove the coupler yoke.

Remove the transmission top cover.

Engage two different gears in the transmission to lock the lower shaft and remove the lower shaft driver coupler/nut.

Remove the transmission input shaft and cage assembly.

Remove the three cap screw retaining the rear top shaft bearing and slide the shaft forward and out of the transmission.

Remove the brake pedal shaft from the rear housing.

Remove the PTO assembly.

Slide the lower shaft back and remove the front counter bearing and cage.

Remove the snap ring retaining the rear bearing to the counter shaft.

Remove the rear counter shaft bearing.

Lift up on the front of the counter shaft and slide the assembly forward and out of the rear frame.

The gears on the counter shaft can be removed with a press.
 
All this info and help has been fantastic!!!!!
Today I had a chance to work on the M for a minute. I removed the belt pulley cover plate and found nothing unusual on inspection. So I put two bolts back in the plate and ran the tractor and mower till the problem showed up.
At this point I lowered the rpm as low as possible threw a large chock in front of the tires and while the tractor was running but not moving with clutch out and in gear I pulled the belt pulley cover off.
The constant mesh gears were turning as if the transmission was placed into neutral. If I shut the tractor off with out any changes you could gear the trans pop back into gear about the time the motor was on its last revolution. After further inspections and looking around it seems tht the problem is further back in the transmission where the shift forks are.

I won't be able to remove the top plate till early next week...but I am hopefull that the problem will be obvious when I get the plate removed
 
This site wont let me post a photo for some reason.

I was going to post the photo and a diagram.

All the gears I can see so far look great and show no signs of damage.

With belt pulley cover off...transmission in neutral and the clutch depressed you can spin the constant mesh gears by hand because while the trans is in neutral the gears are not locked to the transmission main shaft.

This is what happens during the moving/mowing problem. The constant mesh gears are turning but the main/top transmission shaft is not turning like the shifter is in neutral even though it is fully engaged in gear.


With the tractor not running I shifted the trans through all gears multiple times and watched the gears slide around in the trans. And the shifter feels great.

It is killing me not being able to work on this thing till next week!!!!!
 

Was the lower transmission shaft turning also along with the constant mesh gear when you blocked the wheels and looked in. Originally you said 1 through 4 speeds and the pto didn't work. Lower shaft is probably broke inside a gear or a key is no longer retaining a gear to shaft. Gear spinning on shaft and shaft not turning. Unlikely that both the 3,4 and 1,2 gears both have a stripped key. Since 1 to 4 didn't work when tractor stopped I think the problem is toward the front, inside the constant mesh gear or inside the 3 and 4 double gear.
 
The upper transmission shaft was not spinning when the problem is happening. The constant mesh gears at the front of the two transmission shafts are spinning....I did not see if the lower shaft was spinning but I know the gears are spinning....thing slings gear oil out like crazy when I pop the cover off so I only looked for a split second a few different times.

Thanks for your help...what other info do you need to pinpoint the problem?

To me it seems like an issue further back in the transmission. I can put trans in neutral and push in the clutch and rotate the constant mesh gears by hand...put in gears 1-4 can't rotate constant mesh gears even with clutch pushed in. But when the problem happens the gears are spinning the shaft is not and the trans is in gear. Almost like it slipped i between gears although the shifter if firmly in gear.
 
4th gear is the next set to rear of the constant mesh gear and transmission input shaft gear. You can see through the belt pulley gear box drive hole if the top and bottom gear are in mesh when in 4th. If you can see those gears are in mesh and the top transmission shaft doesn't turn the problem has to be with the counter shaft inside the constant mesh gear or just inside the 3rd and 4th drive gear.
Also unless you have a PTO failure and it stops turning when engaged, it would be a failure of the lower transmission shaft to transfer power to it if the constant mesh gear is turning or even if its turning the front of the lower shaft.
 

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