MF 135 Hydraulic question

WolfRunFarm

New User
I have an old MF 135. Years, or likely decades ago, an add-on hydraulic valve bank to operate the end loader lift and tilt functions. The valve bank cracked this spring so I decided to remove it rather than try to get it repaired or replaced since the tractor hasn't had the loader installed for several years.
The original cover cap for the hydraulic lift cover had long ago been misplaced, so I purchased one and installed it.
Not knowing the original configuration of this piping, I installed a plug in the pipe port on the side of the cap like I've seen in several pictures online.
Now, when I start the tractor, the lift arms immediately pressurize and the system seems to deadhead. The lift arm control lever doesn't work as far as letting the arms down.
The lift arms and control lever worked when the diversion valve was in the correct position prior to the valve bank cracking .

Did I plug a return that should be open when I installed the cover cap?

I'm open to any suggestions as to my issue here.

Thanks,
 
I don't think you did anything wrong.

Possibly someone modified the linkage to divert all hydraulics to the loader, just a guess.

But inside the right cover, below the seat, is the linkage to control the lift. Open the cover and see if anything looks out of place. The roller lever that extends up from the pump is what controls the pressure to the lift cylinder. When functioning properly there is position control and top limit control so the pump never deadheads. The roller only moves a fraction of an inch to raise of lower the lift.

Here is some info on it, a shop manual would be a good investment. Be extremely careful not to reach in there with it running!

Might post on the MF board for more specific instructions.
Controls
 
Hello, if your tractor has only operated the front end loader via the
valve block in it’s previous life then it is quite possible that the control
valve in the pump is stuck in the pumping position. With this valve
fitted pressurised oil will be sent up the stack pipe to the valve block
and then back to the transmission via the plain hole in the cover
under the plate or out to operate the loader as required. If the control
valve is stuck oil will be sent to raise the 3-point until it is fully raised
and then the relief valve will blow.
Drain about 1.5gals from the transmission and remove the rh side
cover. Operate the Position Control lever on the quadrant and watch
what happens inside. When you move the PC lever upwards the
pump lever upwards the pump lever should move rear wards and
allow the pump to pump oil. When you lower the quadrant lever the
pump lever should move forwards into the discharge position. If the
pump lever does not respond to the quadrant lever commands then it
looks like the cv is stuck. Try moving the pump lever back and forth.
It may free of its own accord . It must be absolutely free.
DavidP South Wales
 
I appreciate the info and suggestions.
I didn't dig into it any deeper after installing the cap.
I'll get back into it once I get the hay done and see what I can find.

Thanks,
 

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