M125X Hydraulic issue

[Fedup]

I'm back with this M125X yesterday, The issue this time seems to be the hydraulic pump itself. Over recent months it has developed a problem picking up prime. When first started in the morning the hydraulics don't work until the engine is revved up to nearly full throttle for twenty or thirty seconds, after which the pump starts working. It will work for the rest of the day without problem, engine stopped and started multiple times.

My first thought was something suction related. Both pumps are mounted side by side, and each have a separate suction supply from a common filter manifold. The steering/transmission pump has no problem coming to life when first started even at idle speed. The hydraulic pump, not so much. After inspecting the two different supply sides for oil leaks, obvious problems, etc, tightening hose clamps with no effect I decided to remove the seat and panels for a look at the pumps. The pump was wet, with signs of body seals leaking to some degree, so I pulled it off to install a seal kit.

The body seals were indeed hard, brittle, and in need of replacement. The wear plate seals were both actually broken as well as brittle. The gears, bearings, and housing look good, so new seals, it's back together, all lubed up and back on yesterday. It didn't pick up and go to work as I'd hoped it would. Once going, it seems to perform well enough, with no leaks. Left overnight with everything still exposed it was started again today and once again it won't prime without a few seconds of elevated RPM. I have not replaced the hose/coupler or the O ring on the filter manifold yet. Not sure if either would make much difference at this point.

Any thoughts?

 

[North Idaho Wolfman]

I'm back with this M125X yesterday, The issue this time seems to be the hydraulic pump itself. Over recent months it has developed a problem picking up prime. When first started in the morning the hydraulics don't work until the engine is revved up to nearly full throttle for twenty or thirty seconds, after which the pump starts working. It will work for the rest of the day without problem, engine stopped and started multiple times.

My first thought was something suction related. Both pumps are mounted side by side, and each have a separate suction supply from a common filter manifold. The steering/transmission pump has no problem coming to life when first started even at idle speed. The hydraulic pump, not so much. After inspecting the two different supply sides for oil leaks, obvious problems, etc, tightening hose clamps with no effect I decided to remove the seat and panels for a look at the pumps. The pump was wet, with signs of body seals leaking to some degree, so I pulled it off to install a seal kit.

The body seals were indeed hard, brittle, and in need of replacement. The wear plate seals were both actually broken as well as brittle. The gears, bearings, and housing look good, so new seals, it's back together, all lubed up and back on yesterday. It didn't pick up and go to work as I'd hoped it would. Once going, it seems to perform well enough, with no leaks. Left overnight with everything still exposed it was started again today and once again it won't prime without a few seconds of elevated RPM. I have not replaced the hose/coupler or the O ring on the filter manifold yet. Not sure if either would make much difference at this point.

Any thoughts?

Yea it's got a suction problem, and that was probably the reason for all the damaged pump seals, it got too hot.

I personally would pull all of the suction side off and look into every component, looking for scracks, splits or any other oddity, and replace all the O-rings, and maybe all the hose sections.

 

[Fedup]

No doubt you know Kubota far better than I do, so your opinions would be valued. I had planned to replace at least the suspect hose connector and the lower O ring as a next step. The O rings on the lower tube may come later if that fails to make any improvement, but since the steering pump has yet to show the symptom I'm leaning toward something other than the common circuit.

I think the pump seal conditions are probably a result of how the system is treated. The tractor spends it's time operating a laser guided drag scraper supplied with oil from one remote valve in constant use. I believe the flow demand of the unit is less than the tractor's output from the remote and probably runs at a higher pressure than it should. I think that operating the tractor in this manner is the reason for the pump problems to begin with. I haven't confirmed that yet, but will once the pump issue is resolved. It may require some means of reducing the flow/pressure through the lines to the scraper.

 

[North Idaho Wolfman]

No doubt you know Kubota far better than I do, so your opinions would be valued. I had planned to replace at least the suspect hose connector and the lower O ring as a next step. The O rings on the lower tube may come later if that fails to make any improvement, but since the steering pump has yet to show the symptom I'm leaning toward something other than the common circuit.

I think the pump seal conditions are probably a result of how the system is treated. The tractor spends it's time operating a laser guided drag scraper supplied with oil from one remote valve in constant use. I believe the flow demand of the unit is less than the tractor's output from the remote and probably runs at a higher pressure than it should. I think that operating the tractor in this manner is the reason for the pump problems to begin with. I haven't confirmed that yet, but will once the pump issue is resolved. It may require some means of reducing the flow/pressure through the lines to the scraper.

Do you remember, is the issue more on the inboard or outboard pump?

That system uses a air evacuator system, so I'm wondering if there is an issue with that system.
I'll look into if I have the WSM and see if there is anything to that.

 

[Fedup]

Unclear on the question. This is the hydraulic pump. The two pumps are side by side on top of the rear housing directly below the seat. From the rear this one is to the left of center, the transmission pump is to the right of center. They both drive from what the parts list refers to as the PTO valve body. Not aware of any air evac system.

 

[North Idaho Wolfman]

Pump on the left looking forward is the inboard pump.
And yes it has a air evac system, still trying to get more information on it.

 

[Fedup]

I've studied the above posted parts diagram many times. I concluded that the filter base has two filters, each connected to a common supply tube from the rear housing. Each pump has it's own suction tube leading from the filter base. I've always assumed they draw fluid from a common filtered oil passage in the base. Maybe I'm wrong in that assumption. Could be only the filter inlet is common, and the pumps each draw from a separate filter and separate outlet on the filter base. Can anyone confirm that one way or the other?

I know the filters were changed at some point before I was involved and had no effect on the problem so I have not yet gone in that direction, again ASSUMING both pumps draw from a common source of two filters in parallel.

 

[Marcos]

Hi there.

Have you solved the problem with the kubota M125X? I have the same problem.

When first started in the morning the hydraulics don't work until the engine is revved up to nearly full throttle for twenty or thirty seconds, after which the pump starts working.

Thank you very much for your help.

 

[moesfarm]

I got a M105X the little brother to your M125X. My PTO started slipping a week ago using a disc mower. I am still trying to diagnose my problem. My problem is with the other pump.
I finally got the heavy air ride seat out the back window. I am dreading getting it back in.
What is the best way to remove the very heavy air ride seat? I unbolted mine and flipped it straight back out of the rear window. Should i have rotated it 180 degrees before i tried to flip it and get it out of the window?

 

[Middlemesa]

I'm back with this M125X yesterday, The issue this time seems to be the hydraulic pump itself. Over recent months it has developed a problem picking up prime. When first started in the morning the hydraulics don't work until the engine is revved up to nearly full throttle for twenty or thirty seconds, after which the pump starts working. It will work for the rest of the day without problem, engine stopped and started multiple times.

My first thought was something suction related. Both pumps are mounted side by side, and each have a separate suction supply from a common filter manifold. The steering/transmission pump has no problem coming to life when first started even at idle speed. The hydraulic pump, not so much. After inspecting the two different supply sides for oil leaks, obvious problems, etc, tightening hose clamps with no effect I decided to remove the seat and panels for a look at the pumps. The pump was wet, with signs of body seals leaking to some degree, so I pulled it off to install a seal kit.

The body seals were indeed hard, brittle, and in need of replacement. The wear plate seals were both actually broken as well as brittle. The gears, bearings, and housing look good, so new seals, it's back together, all lubed up and back on yesterday. It didn't pick up and go to work as I'd hoped it would. Once going, it seems to perform well enough, with no leaks. Left overnight with everything still exposed it was started again today and once again it won't prime without a few seconds of elevated RPM. I have not replaced the hose/coupler or the O ring on the filter manifold yet. Not sure if either would make much difference at this point.

Any thoughts?

When you pulled the pump did you remove the whole base with both pumps? And did you get the hydraulic pump issue solved? I have the same issues with mine.

 

[Fedup]

When you pulled the pump did you remove the whole base with both pumps? And did you get the hydraulic pump issue solved? I have the same issues with mine.

NO. I removed only the one pump that had the problem. I did end up replacing both suction hose couplers, hose clamps, and the O rings on all four of the upper suction pipes. That got rid of the problem so I didn't go into the lower suction pipe leading into the filter base. That would have involved draining the fluid, and spending some time working under the tractor (in the mud) so opted to let that ride at the time.

The tractor has been in operation ever since and the problem has not reoccurred. Knowing these people, I would have heard about it.

 

[Middlemesa]

NO. I removed only the one pump that had the problem. I did end up replacing both suction hose couplers, hose clamps, and the O rings on all four of the upper suction pipes. That got rid of the problem so I didn't go into the lower suction pipe leading into the filter base. That would have involved draining the fluid, and spending some time working under the tractor (in the mud) so opted to let that ride at the time.

The tractor has been in operation ever since and the problem has not reoccurred. Knowing these people, I would have heard about it.

Today I went ahead and pulled the hydraulic pump by itself instead of the base as you did, found the suction tube going into the pump was missing the retaining nut, since this has been a problem since I bought the tractor with only 17hrs on it, I believe this was an original issue from day one. Will get new oring and rubber couplers next week when shop opens, Thanks for the reply will let all know of the outcome.

 

[Fedup]

I'm not sure what nut you're talking about. All I remember was bolts holding everything together.

 

[Middlemesa]

I'm not sure what nut you're talking about. All I remember was bolts holding everything together.

The tube going to the Hydraulic pump has a stud where the pipe connects, there was no nut to hold the suction pipe in place is what I found.

 

[Fedup]

It's been too long since I was in there. I don't remember if there were studs involved, but missing a nut on one could well have an effect on sealing the tube to the pump housing.