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Discussion Starter #1
recently experienced a with system. working one day/nothing next day. emptied an. and refilled with new hyd oil. still no pressure to lift drawbar (not even trying)
anyone have a suggestion as to problem. hoping not to have to rebuild whole unit. never experienced situation before.
thanks.
 

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I'm not super familiar with the M, but does it have the manual engagement for the hydraulic pump? My 60 has a handle that has to be rotated to engage the gear to drive the pump.


By the way,
:wgtt:
 

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There is a threaded hole on top of the touch o matic to screw a guage in to check for pressure or you can take one of the nuts loose on one of the Hydraulic fittings and see if you have pressure. If you do not have pressure, You have pump problems. The pump is located on the front of the engine. It has two gears inside it that pump the fluid. I have seen the teeth break on the 2 gears. All this assumming you are talking about a late 40's to early 50's John Deere M tractor. I have a 1948 I am in the process of restoring.
View attachment 26424 View attachment 26425

There are 2 types of pumps depending on what your serial number is.
 

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I'm not super familiar with the M, but does it have the manual engagement for the hydraulic pump? My 60 has a handle that has to be rotated to engage the gear to drive the pump.


By the way,
:wgtt:
Pump drives off a coupling mounted on front of cam gear that is turned by the crank.
 

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I'm going from memory here because I no longer have my 40U to go look at it.

Is the TOM lever actually moving the TOM linkage? I believe the lever is held onto the shaft it is mounted to with friction discs. Kind of like the friction discs where the throttle lever connects to the throttle shaft at the dash. If the discs loosen up, the TOM lever will move, but the shaft wont be.

Also, there is a linkage coming off the TOM shaft that connects to the automatic depth adjustment where the toplink mounts on the tractor, to automatically adjust the 3pt height when running a plow. I am fairly certain at least the later Ms had that linkage. If that linkage gets knocked off it will cause problems adjusting the TOM.

Lastly, I seem to recall a pressure relief valve somewhere on the TOM housing that if it isn't adjusted properly it will go into bypass all the time.

It has been at least 10 years since I had a TOM apart on my 40U, so I may be a bit fuzzy on some of this.

It is also possible the TOM piston is worn or a seal on it went bad. It isn't too bad pulling the TOM off and rebuilding it. I wouldn't do it if it's not needed, but it wasn't a big project, other than the weight of the TOM housing.

The worst would be if something happened to the hydraulic pump. My pump had a leaky seal and ended up dumping about a gallon of hydraulic fluid into the engine crankcase. Is was easy to diagnose by the overfilled engine oil level. But the TOM still worked, it just kept getting low on fluid. The big problem would be if the coupling between the camshaft and hydraulic pump drive broke. Then you would have zero pressure in the hydraulic lines, even if the TOM is full. The pump on the 40 is like the second one Keefus posted for the later Ms.
 

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recently experienced a with system. working one day/nothing next day. emptied an. and refilled with new hyd oil. still no pressure to lift drawbar (not even trying)
anyone have a suggestion as to problem. hoping not to have to rebuild whole unit. never experienced situation before.
thanks.
This may be of some help to diagnose your problem.
Go to John Deere website and register and get a parts breakdown for your tractor. It is very helpful when having problems. It Will give you some insight on how things look and helps with
disasembly and assembly.
Go here and register.
https://www.deere.com/wps/dcom/en_US/parts/parts.page
Then click on Agricultural Parts and Attachments.
Scroll down to Search for Parts. Look up parts using John Deere parts catalogs.
Click the Look up parts.Then put a M in the find box and check exact model search.
PDF files will come up, click on M JDTractor, after the file loads you can save it to your computer and print them out if you want a hard copy.
Good luck with your problem.
keefess :greentractorride:
 

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Discussion Starter #7
touch a matic-----------------

There is a threaded hole on top of the touch o matic to screw a guage in to check for pressure or you can take one of the nuts loose on one of the Hydraulic fittings and see if you have pressure. If you do not have pressure, You have pump problems. The pump is located on the front of the engine. It has two gears inside it that pump the fluid. I have seen the teeth break on the 2 gears. All this assumming you are talking about a late 40's to early 50's John Deere M tractor. I have a 1948 I am in the process of restoring.
View attachment 26424 View attachment 26425

There are 2 types of pumps depending on what your serial number is.
thanks for the input. good place to start for sure.
 

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Discussion Starter #8
There is a threaded hole on top of the touch o matic to screw a guage in to check for pressure or you can take one of the nuts loose on one of the Hydraulic fittings and see if you have pressure. If you do not have pressure, You have pump problems. The pump is located on the front of the engine. It has two gears inside it that pump the fluid. I have seen the teeth break on the 2 gears. All this assumming you are talking about a late 40's to early 50's John Deere M tractor. I have a 1948 I am in the process of restoring.
View attachment 26424 View attachment 26425

There are 2 types of pumps depending on what your serial number is.
thanks, much appreciative to all members for their replies and trouble shooting info. Jim D.
 
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