MF135 Hydraulics issue

certaindeath · Jun 20, 2017

Looking for a bit of help with my 135's hydraulics. I seem to keep loosing oil flow/pressure to my front loader and aux ports.

I have a two way diverter under the seat. One way feeds a three spool valve for my loader the other feeds a constant aux port on the back for running my backhoe.

When I loose flow/pressure in it the loader or backhoe rams are extremely slow and a little judery. I also get a prominent knocking from the transmission when the cylinders reach their extents, normally I just hear the relief valve kick in and dump the oil.

I had the diverter and side cover off tonight and checked the draft/position mechanisms were moving and all seemed ok. I fiddled with the levers in the transmission to make sure everything was free then ran the tractor with the cover off and all appeared to be fixed and working fine. Stuck the cover back on and set about digging again and after a few minutes it started again.

Not entirely convinced its a pressure problem as I can still lift the back wheels off the ground with the backhoe, albeit very slowly.

I found if I moved the draft and position levers through their sweeps and then put them back to draft fully up and position to constant pump it would work fine for a bit and then problem would re-occur. The draft and position levers are a bit stiff and moving one tends to pull the other a bit as well.

Can anyone help me pinpoint what might be wrong. Its a real pain as I'm trying to get drains dug in the good weather.

Thanks

midwesternhayfarmer · Jun 20, 2017

certaindeath said:
Looking for a bit of help with my 135's hydraulics. I seem to keep loosing oil flow/pressure to my front loader and aux ports.

I have a two way diverter under the seat. One way feeds a three spool valve for my loader the other feeds a constant aux port on the back for running my backhoe.

When I loose flow/pressure in it the loader or backhoe rams are extremely slow and a little judery. I also get a prominent knocking from the transmission when the cylinders reach their extents, normally I just hear the relief valve kick in and dump the oil.

I had the diverter and side cover off tonight and checked the draft/position mechanisms were moving and all seemed ok. I fiddled with the levers in the transmission to make sure everything was free then ran the tractor with the cover off and all appeared to be fixed and working fine. Stuck the cover back on and set about digging again and after a few minutes it started again.

Not entirely convinced its a pressure problem as I can still lift the back wheels off the ground with the backhoe, albeit very slowly.

I found if I moved the draft and position levers through their sweeps and then put them back to draft fully up and position to constant pump it would work fine for a bit and then problem would re-occur. The draft and position levers are a bit stiff and moving one tends to pull the other a bit as well.

Can anyone help me pinpoint what might be wrong. Its a real pain as I'm trying to get drains dug in the good weather.

Thanks

In what position on the diverter operates the three point hitch? It almost sounds like the pump is not into the constant pumping mode. Are you moving the position lever all the way back past the stop? If I understand the Scotch Yoke pump operation correctly, when the three point reaches the top of its travel,the pump senses this and the pump stroke centers itself and quits pumping. From what you describe, it. Sounds like the pump is sensing the end of the cylinder stroke on the loader and backhoe the same as the three point and centering the pump stroke reducing the flow and pressure. Try moving the position lever farther back or check for a broken cross pin between the position lever and shaft.

certaindeath · Jun 21, 2017

Hi, thanks for the reply. Positive its going into constant pump mode. The lever is past the stop and if tried moving it further towards the high pressure position just to be sure.

When I had the side cover off I could see oil being recirculated when I moved into constant pump which I assume confirms it was in the right place.

I'll check the pins today and ensure they're all correct.

Thanks

Ian