I have a 2012 Kubota M126GX. I purchased it used when it had about 1200 hrs on it. About a year after I got it, one of the rear auxiliary hydraulic valves locked up. We had the dealership look at it and they replaced the valve. About a year later it happened again. I replaced another valve and installed it myself. Now (about 2 years later) two more valves locked up. I took them to a hydraulic repair shop and they couldn’t fix it because the bore was slightly scored. I then took the valves to a Kubota dealership and had them take a look. They put the valves back together for me and said the scoring is small enough that it shouldn’t be an issue. They also said it was from a small piece of metal that would have gotten stuck in the valve. I installed them back on the tractor and now I have very little flow and only about 200 psi of pressure (should be around 2800 psi) the front end loader, 3pt hitch, steering and brakes are all working fine and have never given me issues. I have tried to find problems in the relief valve like a broken spring or foreign piece holding it open but it looks clean. I change the hydraulic filter yearly and changed the hydraulic fluid after this last breakdown. Hydraulic level is good. Is there anyone out there that has a diagram or schematic of this hydraulic system? Or any advice on something else to check? I don’t know where these metal fragments are coming from (internal from the tractor or an implement) and I want to get this issue fixed. New valves are too expensive to be replacing this often. Thank you for your help.
M126GX hydraulics
- Thread starter Sask80
- Start date
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
I know nothing about that tractor but if you are getting low flow and pressure at the valve outlets but good pressure and flow elsewhere the valve is not opening or the outlet is obstructed.
I lookef at the owners manual - do you have flow control on the valves?
Is the hydraulic system open or closed center?
Are you measuring pressure at a quick coupler?
Dan
Last edited:
North Idaho Wolfman
Moderator
Staff member
Lifetime Member
Equipment
L3450DT-GST, Woods FEL, B7100 HSD, FEL, 60" SB, 743 Bobcat with V2203, and more
When your changing the filter are you reinstalling the magnet?
Are you using remote implements on other tractors?
Have you pulled and checked the Assy. relief valve?
Are you using remote implements on other tractors?
Have you pulled and checked the Assy. relief valve?
The valves do have individual flow control. They are at max flow. Not sure if I have open or closed center. Is there something I can do to verify that? I am measuring with a quick coupler. It is a male pioneer hydraulic fitting attached to a good quality gauge. I believe I have checked the right assembly relief valve and it seems to be ok. We have used other tractors on all of the other implements we have and not had any issues. As for the magnet, I didn’t notice a magnet in the filter or in the filter housing. I will show some pictures of what it all looks like.
Note: there is supposed to be 3 valves on this block. The third one is currently at the dealership for having flow in only one direction. The last time I talked to a service technician there, he told me it is a problem in the relief valve. Am I checking the wrong spot? I checked inside the caps on the block directly below the remote valves. There is a spring on the left side.
Also, thank you very much for your time responding to me. I really appreciate it.
Also, thank you very much for your time responding to me. I really appreciate it.
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Internet sources say the tractor has open center hydraulics. What relief valve is the service guy talking about and where is it?
If you only have problems with one remote the problem is in that work section.
Have you verified the control linkage is working and the spool is being fully shifted in both directions?
Does the valve have float or self canceling detent?
In any event I would suggest removing the coupler from the malfunctioning work section and connecting your pressure gauge directly to the work port on the section. That will eliminate the couplers from the equation.
Dan
Last edited:
The pressure problem is with both rear remotes and in both directions on each. The service tech told me to check the relief valve which is located below and kinda tucked in closer to the cab. It is visible in my second picture. It is painted grey and has a jamb nut on it. I checked that one but found no problems and also found that that was for the 3 pt hitch. I tried starting the tractor and moving the hydraulic levers with that relief valve off and no oil came out. I then tried the 3 pt and oil flowed out.
I then tried just below the remote valves. There are two hex head plugs on either side. They are visible in the pictures but are tough to see. They are rust colour.
I did not try moving the levers while running with one of these plugs off and I did not try pulling the hex key (Allan) plug off the front below the remote valves. I will try this tomorrow to check for flow.
The valves have self canceling detent.
From what I remember, the tractor should have a slight sound difference when I push or pull the lever, it’s not much but just a slight groan or hum. That is gone now.
I then tried just below the remote valves. There are two hex head plugs on either side. They are visible in the pictures but are tough to see. They are rust colour.
I did not try moving the levers while running with one of these plugs off and I did not try pulling the hex key (Allan) plug off the front below the remote valves. I will try this tomorrow to check for flow.
The valves have self canceling detent.
From what I remember, the tractor should have a slight sound difference when I push or pull the lever, it’s not much but just a slight groan or hum. That is gone now.
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Thats informative but I fail to see anything that would point to a relief valve issue. The relief you describe is lift cylinder safety overload and after the remotes. I would think the only pressure relief for thevremotes is the main pump relief. A hydraulic schenstic would be helpful.
Lets break this down a bit.
- Since all of the outlets have the same problem it would seem the problem is not in the work sections.
- You are checking pressure at the individual outlets and have no pressure on half the outlets in one direction but full pressure in the others.
If you hook a DA cylinder up to one of the sections does it operate in just one direction or not at all?
Dan
Sorry for the confusion, there was only one valve that had pressure in only one direction, I took that to the dealership to be repaired. I am guessing that is a coupler problem, not valve. After taking that off and putting the two re-built valves back on, now I have the no pressure in either direction problem.
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
This is starting to become wack-a-mole
.Ok - originally there were three work sections in the stack and one had no pressure on one work port. It was removed and now we have two rebuilt work sections in the stack and no pressure at any outlet but the 3pt stil works fine - correct?
Dan
Sorry if I am not being clear, I know it’s all very confusing.
Here is the timeline.
- 3 properly working remote valves on tractor. (Numbered 1,2,3)
- 2 of these locked up and would not move in either direction. (Numbers 2,3)
- I removed the two bad valves and took them in to be rebuilt. (Numbers 2,3)
- I kept running the tractor with one properly working valve. (Number 1)
- The one remaining valve started only having flow in one direction. (Number 1)
- I got the two rebuilt valves (2,3) back from the shop and dropped off the one (1) with flow in one direction.
- I put the two rebuilt valves (2,3) back on the tractor and now have a small amount of flow and 200 psi of pressure
- Brakes, Steering, Front end loader, 3pt hitch and PTO have all remained in-affected throughout entire life of tractor.
Here is the timeline.
- 3 properly working remote valves on tractor. (Numbered 1,2,3)
- 2 of these locked up and would not move in either direction. (Numbers 2,3)
- I removed the two bad valves and took them in to be rebuilt. (Numbers 2,3)
- I kept running the tractor with one properly working valve. (Number 1)
- The one remaining valve started only having flow in one direction. (Number 1)
- I got the two rebuilt valves (2,3) back from the shop and dropped off the one (1) with flow in one direction.
- I put the two rebuilt valves (2,3) back on the tractor and now have a small amount of flow and 200 psi of pressure
- Brakes, Steering, Front end loader, 3pt hitch and PTO have all remained in-affected throughout entire life of tractor.
Russell King
Well-known member
Equipment
L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
I should stay out of this since I am weak in hydraulics but…
Since you have number one at the shop I assume it was the first in line from the pump and now number two is first.
Does each valve have to have a power beyond sleeve or just the first one?
Does number two valve need a power beyond sleeve added?
Are the inlet ports in number two in the same place as number one or is it blocking the flow through the stack?
Since you have number one at the shop I assume it was the first in line from the pump and now number two is first.
Does each valve have to have a power beyond sleeve or just the first one?
Does number two valve need a power beyond sleeve added?
Are the inlet ports in number two in the same place as number one or is it blocking the flow through the stack?
I am not real good with hydraulics either.
All 3 remote valves are identical, they are stacked up on each other with a cap placed on the top one. I have posted a picture of two of them mounted on the tractor. I have also posted a picture of a remote valve sitting on a bench. That picture the top of the valve. Here is a picture of the bottom.
The 3 small outside holes are for the mounting bolts.
All 3 remote valves are identical, they are stacked up on each other with a cap placed on the top one. I have posted a picture of two of them mounted on the tractor. I have also posted a picture of a remote valve sitting on a bench. That picture the top of the valve. Here is a picture of the bottom.
The 3 small outside holes are for the mounting bolts.
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
These are work sections in a stack valve. If there was a power beyond which there is not it would only be in the outlet section that caps the stack.
Dan
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
OK - we are back on track. I am having trouble with those pictures. It does not look like any open center valve I have seen. Based on the class of tractor and rated flow I am beginning to suspect it is a closed center load sensing valve with two independent pressure delivery ports and a center load sense / pilot pressure port.
In any event based on the timeline it seems likely that there is debris in that area in the system and if my guess about load sense is correct the debris is clogging the pilot passages and disrupting the signal to the controller. Definitely over my head here but if it were my problem I would disassemble and clean every passage in each work section,
Dan
Last edited:
TheOldHokie
Well-known member
Lifetime Member
Equipment
L3901/LA525, B7200DT/B1630, G2160/RCK60, G2460/RCK60
Thanks to the crazy way this site handles post composition that comment got lost in my final version. Does not apply after seeing the pictures.
Post #13 pretty much sums up what I know and dont know. The one way behavior makes more sense if the valves are in fact closed center load sense (CCLS). In that scenario the pilot signal tells the controller to supply pressure to one of the ports I labeled P1 abd P2. The pilot passages are pretty small and easily obstructed by debris. But again in deep water here and barely able to dog paddle.....
Dan
Thank you all so much for your suggestions. I am going to contact the dealership tomorrow to get a breakdown/schematic of the entire system. Looks like I am going to have to start digging deeper into this than I want. Just thought I would throw it out and see if someone else knew about something I didn’t or had a similar issue but by the sounds of it, it’s not a common problem with these tractors. Thanks again.