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Discussion Starter #1
Hello! This question is in regards to the tractor in my signature. I am new to this forum but not new to old tractors... However, this is a problem I've never encountered before. I think something is wrong with the hydraulics but never having owned or operated an M before I'm not completely sure. In short, it lacks the lifting power I think it should have and it is very jerky while under load (a 400# finish mower). Lifting anything heavier than a back-blade results in a groaning/whirring sound from the front of the tractor. Sometimes under a low to mild load the TOM system seems to 'gurgle'. The fluid appears milky, as though it has been aerated.
The conclusion I have come to is that my pump is bad although if there is a way to bleed air out, I'd like to try that before I replace the pump. Any other ideas or am I on the right track?
 

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Thats your pump making the noise you hear comming from the front of the tractor. Check your hyd fluid first to make sure it is full.
You should be able to bleed the pump by cracking the lines that hook to the top of the pump one at a time with tractor running while moving the lift up and down. It could very well be air in the lines causing you problems and aerating the fluid to look milkey.
 

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Discussion Starter #3
Seeing as yesterday was a balmy -0*F I tried wrapping a heavy canvas tarp around the front of the tractor from the alternator to the fuel bowl. It held in enough heat to turn the hydraulics back into a liquid. :laugh: The old gal wasn't happy at first but that seemed to help quite a bit.

I'm currently running 10w oil in the TOM as specified in the owners manual but after reading a few threads on here it looks like modern hydraulic oil is an acceptable alternative for the TOM system. Does anyone else have any winter experience in this area? My experiance is that hydraulic oil is much thinner and so it flows much better in extreme cold.

I live in a part of the world where your snowplow MUST work.
 

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I never owned an M, only a 40, but the M is fairly close to the 40, at least as far as hydraulics are concerned. The hydraulic fluid circulates back through the TOM, even when not being used to raise the lift arms. There is a breather in the TOM unit, and any air in the system should end up there and get bled out. If the lines seem to keep having air in them, I would check to be sure they are all tight up at the pump and air isn't being sucked into the system there. There could also be a leak in the pump body at the mating seam, but I don't think that would be very common.

If the hydraulic system is leaking, it will either be leaking in one of the lines, in the TOM, or at the pump. If the lines or TOM is leaking, you will surely notice the puddle of fluid. If the pump is leaking, it will leak into the engine and you'll wonder why you suddenly have an extra few quarts of oil in the crankcase. Yes, you know why I know this, LOL
 
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Discussion Starter #5
The engine oil is uncontaminated but like all good tractors, there is at least one hydraulic leak on my M. It is going to be hard to pin point the leak because it isn't a very big one, but I guess it only takes a pinhole. The machine holds pressure just fine; implements on the three-point don't drift down even over the course of a few hours. I guess this means my leak is on the return side of the hydraulic circut. I guess that also means that this could be the reason that the pump is ingesting air and the reason that when I pick up on the three-point I hear gurgling from the breather and then the implement raises.

I assume the fittings on the hydraulic lines are the most likely culprit?
 
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Yeah, the return lines basically have zero pressure, so a small leak would be hard to see. That would also be a good source for the pump to be sucking in air. I would check the fittings, but also check the lines over. When I rebuilt my 40 I had to replace several lines because they had been "repaired" with home-made lines. The lines worked, but you could tell right away they were not stock. The cool thing was, a stop at the dealer, and within the week I had brand new factory Deere lines for a 50-year-old tractor. :lol:
 

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Discussion Starter #7
Mine appears to have all factory lines without any kludged-up fittings, splices, or cracks. I'm guessing that the threads which seal the fittings are worn just enough to not seat against each other perfectly. The more I think about it, the more I'm convinced that the problem is on the return side.

Can I use pipe goop (I don't know the real name for it. My Grandpa called it that and used it for black pipe, steel water pipes, and gas lines) to seal the low pressure return side of the hydraulics? Is there a better product or a better way of sealing the system up?
 

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My JD 420W owners manual says use the same oil in the TOM as crank case, so I use 30 weight, but I also live in AZ not the UP. I don't believe you should have to bleed any air out of the system. as it should self purge as the engine runs if there is adequate oil. I don't think you have enough oil in the TOM, mine takes 4 1/2 qts. I think the frothiness you referred to is entrained air from low oil level and the sound is your hydraulic pump. There is a seal in the pump that prevents hydraulic oil from leaking into crankcase, so if you are losing hydraulic oil, check your engine oil level. Good luck.

And by the way, my wife is from Menominee, MI. Went to the Escanaba tractor show a couple oy years ago.
 

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Discussion Starter #9
Resurrecting an old thread

As it turns out the problem was low fluid in the TOM reservoir. The reason for the low fluid was that the gasket between the main housing and the reservoir was torn at the bottom. I replaced the gasket in the fall of '15 and everything went back to operating as it should.

Fast forward to last weekend; I tried to pick up my mower and nothing happened. The underside of the rear of the tractor was soaked in red fluid and I could see little bits of the gasket poking out... torn again... In the same place. :banghead:

Is this a common problem?

The Deere gasket was really thin. Almost like printer paper. Does getting one to use as a template but cutting my own out of a heavier material sound like a better solution?
 
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