1999 M120 Kubota 3pt lift lockout (2026 thread)

[TheOldHokie]

Yes I agree makes no sense. It is a la1301 loader. I will have to re assemble 3pt block to check rear remote flow.

on a side note I purchased a used complete 3pt dist block off eBay and it arrived today. Unknown if it worked but have a 30d return warranty if not working or not what is needed.

Forget the remote flow test for now.

Repeat the compressed air test on the draft control valve. Apply air to port one and if you get air out port 3 try to shut it off with a finger. Can you shut it off and if you can do you get air out of any other place on the vslve?

 

[Pmschmitt]

I get some air out of port 2 when holding port 3 closed and inputting air into port 1.

When blowing air into 1 and air coming out of 3 it has a variable sound and variable flow rate at full blast to the air not just a whoosh.

when I do the same thing on the used block I just received it is a consistent clean whoosh coming out of 3 when air input to 1

 

[Pmschmitt]

Also original block if I blow into 3 only a small amount of air comes out of 1

used block if I blow into 3 easy flow of air out 1

 

[TheOldHokie]

I get some air out of port 2 when holding port 3 closed and inputting air into port 1.

When blowing air into 1 and air coming out of 3 it has a variable sound and variable flow rate at full blast to the air not just a whoosh.

when I do the same thing on the used block I just received it is a consistent clean whoosh coming out of 3 when air input to 1

I think we have found the problem. I dont think air should be coming out of that second port when but you pressurize 3.. Thats where the oil is going rather thsn to tank via the filter. Exactly whats screwed up isn't clear but that is bleeding off the unload back pressure that is used to close the unloader (T1) and send pilot pressurse to shift the main raise spool which opens the C port.

Resist the urge to take that new draft control valve apart.

Put it on the tractor and test the 3pt.

Dan

 

[Pmschmitt]

Ok put on used block

now oil going to filter correctly but still no up or down movement of arms when pressing pilot spool manually

 

[Pmschmitt]

Or when using fender controls or interior right arm controls

Man progress, but this is nuts!!!
Again Dan thank you for your methodical process

 

[TheOldHokie]

Or when using fender controls or interior right arm controls

Man progress, but this is nuts!!!
Again Dan thank you for your methodical process

Crap - I was hoping that would do the trick. Disconnect both solenoids and try manual activation again.

 

[Pmschmitt]

Ok I had the solenoids plugged in when I was trying this earlier. I will try with them unplugged and report back.

I guess if nothing else positive it seems at least one of the problems is in the block

 

[TheOldHokie]

Ok I had the solenoids plugged in when I was trying this earlier. I will try with them unplugged and report back.

I guess if nothing else positive it seems at least one of the problems is in the block

I think all of the problem is in "the block". Going forward can we call it by its proper name - its the "draft control valve".

 

[Pmschmitt]

I disconnected the solenoid wires on the used draft control valve started the tractor and depressed the pilot spools manually

NOTHING changed

 

[TheOldHokie]

I disconnected the solenoid wires on the used draft control valve started the tractor and depressed the pilot spools manually

NOTHING changed

You say "spools" . You should only be pressing the lift spool solenoid.

Dan

 

[Pmschmitt]

Yes I was depressing the lift (green) solenoid. No action. I did also press the blue (lowering) solenoid just to see if anything happens and nothing occurred.

 

[TheOldHokie]

Yes I was depressing the lift (green) solenoid. No action. I did also press the blue (lowering) solenoid just to see if anything happens and nothing occurred.

OK.

Have we established with certainty that inlet oil is flowing throughvthe valve and into the filter? Do you have the engine running at max RPM or close to it when you manually activate the lift solenoid?

Dan

 

[Pmschmitt]

We have established there is oil flowing into the rear filter after the draft control valve. It no long sounds hollow when tapped.

I was only running the tractor at about 1500 rpm but I can rev her up to 2500 if I need to

 

[Pmschmitt]

I ran it at 2800 rpm and nothing not a jolt not a jiggle when manually depressing the lift pilot spool. Oil still going to hydraulic filter

 

[TheOldHokie]

I ran it at 2800 rpm and nothing not a jolt not a jiggle when manually depressing the lift pilot spool. Oil still going to hydraulic filter

Lets summarize what we think we know

Based on the last few rounds of testing it seems we now have solid flow into (P port) and out of the (T1 port) of the valve as shown in this cutaway. Presumably the unloader (compensator) spool is shifted left and the light gray circuit is at a slightly elevated pressure caused by resistance through the filter.

This is the prerequisite state needed to initiate the lift operation as described below. For some reason that is not happening when the lift solenoid is pushed or energized. I am open to suggestions on how to proceed



Dan

 

[Pmschmitt]

I have not figured out how to insert the images from the WSM as well as you.

one thing I will note and am not sure if this changes much but since we are looking at the hydraulic circuit I think it bears mentioning.

in the WSM on pages 8-M14 through 8-M16, the labeling for the lift and lower spools is different than it is in section 8-S18 through 8-S19 DRAFT CONTROL VALVE DISASSEMBLY

in the 8-S18 section it denotes the larger bore spool is the lifting and the smaller bore spool is lowering. My understanding is this is accurate as the green wire on the coil coincides with lift (larger diameter spool) and the blue coincides with lower ( smaller diameter spool).

I believe this may be important as we evaluate where the fluid is in the hydraulic diagram as it appears to be labeled incorrectly.

 

[TheOldHokie]

I have not figured out how to insert the images from the WSM as well as you.

one thing I will note and am not sure if this changes much but since we are looking at the hydraulic circuit I think it bears mentioning.

in the WSM on pages 8-M14 through 8-M16, the labeling for the lift and lower spools is different than it is in section 8-S18 through 8-S19 DRAFT CONTROL VALVE DISASSEMBLY

in the 8-S18 section it denotes the larger bore spool is the lifting and the smaller bore spool is lowering. My understanding is this is accurate as the green wire on the coil coincides with lift (larger diameter spool) and the blue coincides with lower ( smaller diameter spool).

I believe this may be important as we evaluate where the fluid is in the hydraulic diagram as it appears to be labeled incorrectly.

I am not goIng to get distracted by questionng the WSM and chasing documentation ghosts. I am going to focus on the mechanism in hand.

The description of the operation in Section M makes perfect sense and its not what you are getting.

Your original valve was not routing thr neutral flow correctly for reasons we still dont know. That is a completely static state that relies on nothing other than mechanical springs ( and proper assembly) to set the default position of the various spools and poppets.

The salvage valve does that much correctly but still doesnt operatte tye lift spool correctly when the mechanical actuator is opersted. Thats where I sm going to focus my attention.

First question to be answered is does the unloader spool close T1 when that manual overide is pressed. If it does not you are never going to get anything more than standby pressure anyplace in the valve. I am struggling with formulating a way to test or possibly force that to happen.

Kubota seems to treat this valve as a black box. If it doesn't work just replace it with a new one and that may be the easiest solution. Do you want to go that route or do you want to press on with the pig in a poke salvage valve you acquired? It seems to behave better than your original.

Dan