MF 135 Hydraulics

Howdy All...
It's been a while since I posted about this but here goes:
I have a US built MF 135 Gas that formerly had a pressure control servo (I'm assuming it was removed when the tractor was mechanically rebuilt). I also have an auxiliary control box mounted on the top cover, an OEM Massey valve that would have been current with the MF 35/50/65 (Has the two lollipop levers).

I've run into this issue again lately. When I use the LEFT auxiliary valve lever, the Ferguson linkage hesitates and lifts with a slightly jerky upward motion. I have a Ferguson 14N-AO-28 plow mounted at the moment.

The manual for the auxiliary hydraulic valve says to pin the lever back and the hitch linkage will function normally.
>If I use the position control lever on the quadrant, it will go up and down slowly and kick the lever back out.
>If I use the draft control lever and attempt to follow what the Massey service manual, moving the draft control lever down approximately two inches will cause the plow to drop.

In other words, I believe the tech manual as a quick check says to put the draft control lever between two segments on the quadrant and to push down and then up to test the master control spring.

I performed the master control spring test, and if I press down on the plow, the plow starts to fall. If I press up, the plow will start to raise. I have noticed that if I jostle the top link when the linkage hesitates, the plow will raise.

In the spring, the linkage would not work at all. I drained/ran diesel/refilled with hydraulic fluid that meets the Permtran 821XL spec.

My mechanical spidey-sense says that it's probably the control spring or control valve. I can't find any leaks coming from the top of the lift cover nor did I see any fluid spray from where the relief valve is located at.

I have not taken off the top cover yet and removed the pump. Is there anything I need to look for before I remove the top cover that can act as a diagnostic?

Also, David P, years ago you had posted a blueprint for a MF-163 tool which I am assuming is the same as the FT-358 tool mentioned in the US tech manual. My friend couldn't read the dimentions in the picture that was posted in 2009. Could you please e-mail me the file so I can have the tool made?

Thanks,

Christos
Untitled URL Link

Hello Christos,
No sooner done than said with the sketch for the MF 163 tool. You should find this image sharper.
Before going into any thinking about the isolating valve operation have you checked that the control spring adjustment is correct and that the spring is stiff to turn by hand?

The fact that you have a plough fitted can certainly influence the lift if the/any play in the control spring and yoke is just enough to cause an imbalance on the control lever.

With the DRAFT position lever fully lowered check the yoke for end float. Ideally there should be none. If you have not done so it would be worth removing the CS assembly and making sure that the spring is STIFF TO TURN BY HAND.

If the Pressure Control components have been removed presumably you now have a relief valve fitted in the rear plate of the pump and not the plain plug.

I would want to be sure that the CS is correct before looking further.

Cheers

DavidP