1999 M120 Kubota 3pt lift lockout (2026 thread)

[TheOldHokie]

Thanks for Dan. I have disassembled every part of that block inspected and re assembled but maybe I missed something. All spools o rings and springs were intact and moved easily. This includes checking the shuttle valve on the bottom between the spools and the check and compensator valve. I currently have the aux hydraulic block disassembled.

From my reading my understanding was the manual over ride would operate the 3 pt even if electrical issues, but I could be totally wrong.

it would be helpful to understand the touting of the fluid through the rear end casing. I may remove the 3pt controller and blow some air through the passages to see if they go to the filter first or the block

Forget the remotes - they work and you have not described anything to suggest they hsve anything to do with the 3pt problem.

Like I said - do your best to verify operation of the unloader. If it does not operate oil is just going straight to tank and you will never get pressure at the cylinder.

Dan

 

[TheOldHokie]

it would be helpful to understand the touting of the fluid through the rear end casing. I may remove the 3pt controller and blow some air through the passages to see if they go to the filter first or the block

The hydraulic schematic is clear on the oil flow.

Oil from the power beyond port on the aux valve stack is fed firectly to the 3pt valve. When the 3pt valve is in neutral the unloader spool loops it straight back out to the filter and from there to tank. The system pressure relief valve is located upstream of the aux valves. Kubota has used this flow model on dozens of different models


Dan

 

[Pmschmitt]

Ok disassembled the 3pt block entirely again. See pics below. The only oddities were the following:

1. shuttle valve - last part with o ring was difficult to remove. Had to use a pick, but assume this is due to the hydraulic fluid and rubber o ring creating a seal. A magnet would not pull it out.

2. lift solenoid top spring appears to have a "bend" see pics

all else moved freely as I assume it should. All o rings intact

 

[Pmschmitt]

Ok well there is no hydraulic fluid going to the rear filter also. So based on the schematic how would it be bypassing that.
My understanding was the hydraulic fluid left the 3pt cylinder and then went to filter and after filter to tank.

Dan really appreciate you digging into this.

pic of new filter when unscrewed nonoil

 

[TheOldHokie]

Ok well there is no hydraulic fluid going to the rear filter also. So based on the schematic how would it be bypassing that.
My understanding was the hydraulic fluid left the 3pt cylinder and then went to filter and after filter to tank.

Dan really appreciate you digging into this.

pic of new filter when unscrewed nonoil

Where did you get that understanding? The schematic is abundantly clear.

If nothing is going to filter my best guess is unloader is stuck closed and lowering valve is stuck open.

At this point it seemes likely the problem is in the 3pt valve.

Dab

 

[Pmschmitt]

Dan
When you say 3pt valve you are referencing the valve connected to the lever under the seat? Yes?

Thanks. I have removed that check valve and the spring was intact and clean and the plunger was easily movable but I have not removed the entire assembly.

Rebuilding the 3 pt block and spools currently for re assembly

 

[Pmschmitt]

Sorry mis read I think you meant it is in the spool in the block correct?
Paul

 

[TheOldHokie]

Sorry mis read I think you meant it is in the spool in the block correct?
Paul

Draft control valve = 3pt valve = assembly with multiple spools that iz bolted to top of hydrauluc cover.

Dan

 

[Pmschmitt]

Thanks

 

[Pmschmitt]

Alright it is all back together and I haven't tried it yet.
I went back to check the self diagnostics to check the electrical.
on pg 8-S11 of the WSM it has the self diagnostic code. The only code showing is 2 blinks which equates to the lift arm sensor being bad or not connected.

it has shown this diagnostic code (2) before and 3pt has never worked. I am trying to distinguish between hydraulic problem or electric problem. When I go to page 8S2 and 8S3 for trouble shooting it says I should be able to manually override the electronic controls by depressing the pushbutton solenoid.

I am confused as to 2) manual operation of the solenoid valve on pg 8S3. From my understanding I should be able to get the 3 pt to move even if the electrics are FUBAR.

therefore I believe this is a hydraulic issue even though I have taken all the spools out and check valves and all moves easily and nothing is bound. The Problem is the hydraulic block is $2700 and only comes in a complete set. I am just trying to be SURE this is the problem.

thanks again for all and any help. This thing is a PIA

 

[TheOldHokie]

Alright it is all back together and I haven't tried it yet.
I went back to check the self diagnostics to check the electrical.
on pg 8-S11 of the WSM it has the self diagnostic code. The only code showing is 2 blinks which equates to the lift arm sensor being bad or not connected.

it has shown this diagnostic code (2) before and 3pt has never worked. I am trying to distinguish between hydraulic problem or electric problem. When I go to page 8S2 and 8S3 for trouble shooting it says I should be able to manually override the electronic controls by depressing the pushbutton solenoid.

I am confused as to 2) manual operation of the solenoid valve on pg 8S3. From my understanding I should be able to get the 3 pt to move even if the electrics are FUBAR.

therefore I believe this is a hydraulic issue even though I have taken all the spools out and check valves and all moves easily and nothing is bound. The Problem is the hydraulic block is $2700 and only comes in a complete set. I am just trying to be SURE this is the problem.

thanks again for all and any help. This thing is a PIA

You dont seem to be grasping the mechanical operation of the draft control valve. The M (mechanism) section of the manual has a pretty good description of how the valve operates. Reading and understanding that is a good starting point for inspecting the valve.

You have taken the draft control valve apart. After you reinstall the unloader spool in the valve body what position is it in? It should be closed from pump inlet to filter outlet.

Check and verify that with the valve on the bench.

Depending on what you find there we can discuss the next step.

Dan

 

[Pmschmitt]

Dan
I will get it back off and report back.

just for the record the re assembled and cleaned unit DID NOT produce any new results when started and the pilot spool for lift was manually actuated.

I will tear it apart again and report back on the unloader spool.
paul

 

[TheOldHokie]

Dan
I will get it back off and report back.

just for the record the re assembled and cleaned unit DID NOT produce any new results when started and the pilot spool for lift was manually actuated.

I will tear it apart again and report back on the unloader spool.
paul

That is not at all surprusung. The manual overide does exactly the same thing as the electric solenoid and nothing else.

Operation of the main lift spool is via the hydraulic pilot circuit. No oil in the filter is concerning. Either there is no pump flow coming to the valve (seems unlikely) or something inside the vakve is malfunctioning.

The unloader is the first component in the circuit so lets start with it and see if we can get oil flowing into that filter. Then step through the lift circuit in an orderly manner if needed.

Leave the valve off the tractor - theres going to be more testing needed once we see where the initial position of the unloader is.

Dan

 

[Pmschmitt]

Dan
Ok valve is off tractor. Wet with oil at base of 3pt block. I do not see any abnormalities in the unloaded valve. What is your thought as to where to go from here?

 

[TheOldHokie]

Dan
Ok valve is off tractor. Wet with oil at base of 3pt block. I do not see any abnormalities in the unloaded valve. What is your thought as to where to go from here?

 

[TheOldHokie]

I asked you to check its position in the vslve body.. Is the pump inlet open or closed?

Dan

 

[Pmschmitt]

I believe it is open? Here are some pics when I blow compressed air in most of it wants to come back out the same hole but some does escape the outlet

 

[TheOldHokie]

I believe it is open? Here are some pics when I blow compressed air in most of it wants to come back out the same hole but some does escape the outlet

I would expect no resistance to that air. Can you seal it tight enough to build pressure?

PS> labels on the picture would be helpful.

Dan

 

[Pmschmitt]

Ok when I blow compressed air at 120 psi is blows right back out the labeled port 3 in the pic

 

[Pmschmitt]

Port 1 and 2 have filters on the casing of the 3pt hitch. I believe 3 and 4 return back to tank?