3-Point Hitch MF 231 hydraulic issues

wttalvin · Apr 7, 2020

I have a MF 231 made in 1993. 3 point hitch seemed to work till I put a load on them. Would not lift the tiller or mower. I put a pressure gauge where the stand pipe comes out of the plate on the lift cover. Had only 500 PSI at best. Changed the filter and fluid, no improvement. ACGO web site shows/list a RELIEF VALVE (2800 P.S.I.) part number 828927M92. I took the lift plate off, drained the oil and can't find the relief valve. Does any one know what year MF stopped using the preset relief valve on their hydraulic pumps?

Bentrim · Apr 22, 2020

wttalvin said:
I have a MF 231 made in 1993. 3 point hitch seemed to work till I put a load on them. Would not lift the tiller or mower. I put a pressure gauge where the stand pipe comes out of the plate on the lift cover. Had only 500 PSI at best. Changed the filter and fluid, no improvement. ACGO web site shows/list a RELIEF VALVE (2800 P.S.I.) part number 828927M92. I took the lift plate off, drained the oil and can't find the relief valve. Does any one know what year MF stopped using the preset relief valve on their hydraulic pumps? View attachment 649642

There is no relief valve used in this tractor. The main pressure is controlled by the pressure control valve, the tall thing just off the side of the picture. It appears that after SN 9A349239 it was no longer used. I suggest you get a service manual to get the adjustment right before reinstalling the top cover. But if you have issues remove the right side cover and inspect for leaks with the tractor operating or lift the 3 point by hand with the tractor operating shut it off and listening and looking thru the cover for a leak. Be sure to check the stand pipe o rings as they sometimes will blow out and leak.

wttalvin · Apr 22, 2020

Bentrim said:
There is no relief valve used in this tractor. The main pressure is controlled by the pressure control valve, the tall thing just off the side of the picture. It appears that after SN 9A349239 it was no longer used. I suggest you get a service manual to get the adjustment right before reinstalling the top cover. But if you have issues remove the right side cover and inspect for leaks with the tractor operating or lift the 3 point by hand with the tractor operating shut it off and listening and looking thru the cover for a leak. Be sure to check the stand pipe o rings as they sometimes will blow out and leak.

Thanks for the info about relief valve. MF web site had the old style relief valve listed in part list but did not state when it's use was discontinued. I did buy a service manual shortly after buying the tractor about two years ago. The drawings in the manual are not the best. I did see the adjustment on the new style relief valve but as the tractor only had 49 hours on it when I bought it two years ago I was having a hard time comprehending why someone would have been inside the tractor making adjustments. Anyway the problem turned out to be a blown out o-ring where the lift cylinder bolts to the bottom side of top plate. Blown out o-ring most likely caused by the two of the four bolt studs holding the cylinder were broken. All seems to be working so far. Used a 700 lb. mower Monday and a 6 foot tiller today. Also, I did buy two new stand pipe o-rings from a MF dealer, both the NEW black rings were dry rotted. I went back with the original ones.

Bentrim · Apr 24, 2020

wttalvin said:
Thanks for the info about relief valve. MF web site had the old style relief valve listed in part list but did not state when it's use was discontinued. I did buy a service manual shortly after buying the tractor about two years ago. The drawings in the manual are not the best. I did see the adjustment on the new style relief valve but as the tractor only had 49 hours on it when I bought it two years ago I was having a hard time comprehending why someone would have been inside the tractor making adjustments. Anyway the problem turned out to be a blown out o-ring where the lift cylinder bolts to the bottom side of top plate. Blown out o-ring most likely caused by the two of the four bolt studs holding the cylinder were broken. All seems to be working so far. Used a 700 lb. mower Monday and a 6 foot tiller today. Also, I did buy two new stand pipe o-rings from a MF dealer, both the NEW black rings were dry rotted. I went back with the original ones.

Glad you found the issue at least you didn't have to "pull you hair out" to find the problem Back in the 60's MF came with what they called Pressure Control It was a weight transfer system so you could transfer weight off the implement and the front of the tractor so a smaller tractor could be safer and do a bigger job with less wheel spin. Kind of like a draft system for pull type implements. They accomplished it by special hitches and making the relief valve adjustable and lever controllable so the amount of transfer could be varied. When using position or draft the valve was "locked down" and would blow at the system pressure. It appears MF is no longer producing Pressure Control and has gone back to the old "screw in relief valve". Back in the 60's I was fairly new working at a dealer and was given a pocket hang tag that said "Pressure Control make us prove it". Have a Great day.

def38 · May 16, 2020

Bentrim said:
Glad you found the issue at least you didn't have to "pull you hair out" to find the problem Back in the 60's MF came with what they called Pressure Control It was a weight transfer system so you could transfer weight off the implement and the front of the tractor so a smaller tractor could be safer and do a bigger job with less wheel spin. Kind of like a draft system for pull type implements. They accomplished it by special hitches and making the relief valve adjustable and lever controllable so the amount of transfer could be varied. When using position or draft the valve was "locked down" and would blow at the system pressure. It appears MF is no longer producing Pressure Control and has gone back to the old "screw in relief valve". Back in the 60's I was fairly new working at a dealer and was given a pocket hang tag that said "Pressure Control make us prove it". Have a Great day.

Ben, My 231S is a 2003, made in Turkey. It is at the local dealer here in Alabama for repair (no 3 point action). Once inside the case, I suspect something similar to what WTTALVIN found; O-rings and leaks. But, my question has to do with the pump. Can the the scotch pump be replaced without splitting my tractor? While inside, what items should be replaced "while the tractor is open"? I'm thinking pump, diverter valve tube o-rings, hydraulic cylinder and piston. What else?

def38 · Jun 9, 2020

Update. The MF dealer found several issues with my hydraulics.

1- Old hydraulic oil with some water.
2- O-ring changed.
3- Damaged hydraulic oil filter.
4- Adjustment to the drop circuit (the turtle-rabbit valve).
5- Damaged shift lever boots.

All is well now and my wallet is not as heavy as it was previously.

Now the flail mower is vibrating severely and needs a new bearing at the top drive pulley (junk Chicomm bearings are trash). I think I'll install a new bearing and buy a Woodsmaxx flail mower. Anybody need a lightly used flail mower with a new FAG 6207 bearing?