40 hydraulics

[Michael Priar]

Hello, my JD 40 has a relatively loud whining coming from the hydraulics, seems like it is making noise all over - the pump, hoses, rear unit. The lift works fine. Noise goes away when arms are going down, rather loud when raising. Is this a pump problem, or something else? I also have an MT, it has just a little noise (more like a vibration), but that 40 is loud. Any help would be appreciated.

 

[Mike M]

Wonder if it is sucking air ? Check your connections and also see if the factory pipe holders are all there and tight.

 

[Rusty wheel]

Is it running hot? Sounds like it's making noise when it's under a load. When the arms are going down, you're releiving the load on the pump. The noise might be oil going over a relief valve. You only have one way hydraulics.

 

[Kerry50]

Your 40 makes a noise. When the lift arms are all the way up on mine, they drift down slightly and then pop right back up. Anybody have any suggestions as to what is wrong?

 

[Tennessee Wayne]

The drifting down is probably caused by worn piston seals, then the draft control causes it to jump back up.
If you have the service manual, you could try changing the crossover valve lever, under the seat, to dual or single operation and see if this stops it. Could be just one piston causing this. I am using my 420 in the dual position, using only the outside control knob for up and down, and it does not leak down. But will leak down in the other position.

 

[Anonymous-0]

The TOM units have check valves inside that hold the rock shaft or rock shafts in the raised position. Many times these check valves are the cause of the leak down and bobbing problems.

There are tests you can run to determine if it is the piston seals, head gasket or the check valves. Many times a bit of lapping is all the checks need to make them straighten up and fly right.

The 40 shop manual's section on the Touch O Matic units does a very good job of explaining these units.