Kubota KX121-3

[windyvalleyfarmtabby]

Excavator starts but will not move. It obviously has down pressure. But it will not move period. The boom will not move the thumb will not move absolutely nothing. New machine to us so we are a little confused. I checked all the fuses below the seat and all are good. Can someone please help?

 

[Seven Gables]

Are you dropping the safety lever down on the left side of seat? If you are could very well be the safety switch under the lever. Try wiggling the wires or tapping on the switch while activating a function like boom up , sometimes this will momentarily let it come to life

 

[jdtractor]

Already been stated… make sure the lock out lever to the left of the seat is down or all the way forward. It usually has a red handle… good luck. This would be my suggestion.

 

[windyvalleyfarmtabby]

Are you dropping the safety lever down on the left side of seat? If you are could very well be the safety switch under the lever. Try wiggling the wires or tapping on the switch while activating a function like boom up , sometimes this will momentarily let it come to life

Yes its down all the way.i know how to run the machine just all this electrical stuff is not my gig.

 

[Seven Gables]

Another question to help diagnose the issue. Does that machine use mechanical linkage to operate the dozer blade and also the cab swing? Do these functions work? If they are mechanical linkages and don’t work it would indicate a hydraulic related issue, possibly a stuck open master control valve or pump issue.

 

[hayden]

Another question to help diagnose the issue. Does that machine use mechanical linkage to operate the dozer blade and also the cab swing? Do these functions work? If they are mechanical linkages and don’t work it would indicate a hydraulic related issue, possibly a stuck open master control valve or pump issue.

Excellent suggestion. The dozer blade is definitely mechanical. Also perhaps the boom swing. I'm sure there are test ports when you can check for pressure to help narrow things down too.

 

[Mike1955]

Yes it’s down all the way.i know how to run the machine just all this electrical stuff is not my gig.

He is correct. That’s how it act when this lever is not activated. On mine, when I engage this thing it makes a little hydraulic sound. Hope this helps

 

[4570Man]

Another question to help diagnose the issue. Does that machine use mechanical linkage to operate the dozer blade and also the cab swing? Do these functions work? If they are mechanical linkages and don’t work it would indicate a hydraulic related issue, possibly a stuck open master control valve or pump issue.

A 121 excavator doesn’t have any electrical controls beyond maybe the thumb. The main controls are hydraulic pilot controls. Hydraulic pilots are pretty reliable. They might leak a little bit but complete failure of all of them is extremely unlikely. The lap switch lockout controls a solenoid actuated valve that blocks off all the hydraulic flow when it’s up. I suspect that valve or the 12 v source that feeds it isn’t working correctly. Thats where I would start troubleshooting. I don’t think my KX-040 will move the blade or the boom swing with the lap switch up so that test doesn’t prove anything.

 

[Seven Gables]

A 121 excavator doesn’t have any electrical controls beyond maybe the thumb. The main controls are hydraulic pilot controls. Hydraulic pilots are pretty reliable. They might leak a little bit but complete failure of all of them is extremely unlikely. The lap switch lockout controls a solenoid actuated valve that blocks off all the hydraulic flow when it’s up. I suspect that valve or the 12 v source that feeds it isn’t working correctly. Thats where I would start troubleshooting. I don’t think my KX-040 will move the blade or the boom swing with the lap switch up so that test doesn’t prove anything.

Yes I understand completely how the pilot lock out system works, the lockout switch must get power to the pilot lockout solenoid valve which then opens and allows pilot oil to the joysticks and all other Pilot operated functions. However I believe on the older 121 they used mechanical linkage to the blade and house swing directly to the directional control valves in the main valve stack. Now on your 040 and correct me if I’m wrong they changed this to all pilot operated controls off all Valves in the main valve stack. You’re 040 will not operate any functions with the lockout lever raised . With the 121 there is nothing to lock them out, nothing electrical or pilot oil involved, just mechanically operated.
I would agree his most likely cause is either the pilot lockout switch or the pilot lockout solenoid valve. One of his first tests should be to check for power at the solenoid valve when the lockout lever is down . If no power then it’s most likely the lockout switch or the lockout relay. Did you know there’s a relay involved? Now if he does have power to the lockout solenoid then it is most likely the lockout solenoid, either the coil is faulty or the tiny spool valve is stuck.
The lockout solenoid can also very easily be checked by removing the cap on the electromagnet end and insetting a small Allen wrench to manually shift the tiny spool valve and thus allow pilot oil flow to the joysticks and all other Pilot operated controls.

 

[hayden]

The thing on a 121 is that although most of the controls are pilot valves, a few are not and are mechanically locked in position when the safety lever is up. This is definitely true for the track controls, but I can't remember for others.

So if the safety lever is down and the pilot controlled functions don't work, but the non-pilot valve functions do work, then there is an issue in the pilot control system, not the main hydraulics.

 

[Seven Gables]

The thing on a 121 is that although most of the controls are pilot valves, a few are not and are mechanically locked in position when the safety lever is up. This is definitely true for the track controls, but I can't remember for others.

So if the safety lever is down and the pilot controlled functions don't work, but the non-pilot valve functions do work, then there is an issue in the pilot control system, not the main hydraulics.

True . I’m not sure which controls on the 121 are mechanically controlled except I’m quite certain the dozer blade is and 1 or 2 others . If these mechanically controlled functions don’t work it would have to be a hydraulic issue because there’s nothing electrical stopping them from working. It’s just a test to help separate a hydraulic issue or electrical/pilot issue

 

[alexaali]

It sounds like it could be an issue with the hydraulic lock or safety switch. Sometimes, if the safety lock lever isn’t fully engaged, it prevents any movement of the boom, thumb, and tracks. Double-check that the safety lever is in the correct position. Also, it might be worth checking the hydraulic fluid levels and any emergency stop buttons. If everything looks good there, it might be best to consult the manual or reach out to the manufacturer’s support. Hope this helps!

 

[panamaguy]

Are you dropping the safety lever down on the left side of seat? If you are could very well be the safety switch under the lever. Try wiggling the wires or tapping on the switch while activating a function like boom up , sometimes this will momentarily let it come to life

Try this. I just went through the same thingvwith my IHI 15NX. Tested everything and ended up buy a new nachi pump. From (Alibaba.) and yes the sale went great at a good price. But back to your prolbem. The only thing mine would do is blade up, track extension, and house would swing. But no stick movement. Then i discovered if i pushed the travel levers just slightly the boom would work. The nachi pump is really 4 pumps in one and was getting some working pressure from the swing, blade and track extension part of the pump.

 

[Redlined0002]

Replace your hydraulic filters first. Then check for a stuck relief valve. If that doesn't cure it you probably need a hydraulic pump.

 

[panamaguy]

So out of the 4 oarts of the pump parts 1 and 2 ( closest to the motor) were not working. 3 was giving me my swing and 4 was the pilot part. My boom would use a little of 3. Not enough to dig but at least to lift, kurl, my thumb etc

 

[4570Man]

I tested my 40 today and it won’t move the blade or the boom swing with the safety lever up which I didn’t think it would. I’d feel pretty confident the safety mechanism is messed up. Hydraulic pumps don’t usually fail all at once. The chance of multiple pumps failing all at once simultaneously while they worked correctly the last use would be extremely unlikely.

 

[panamaguy]

I tested my 40 today and it won’t move the blade or the boom swing with the safety lever up which I didn’t think it would. I’d feel pretty confident the safety mechanism is messed up. Hydraulic pumps don’t usually fail all at once. The chance of multiple pumps failing all at once simultaneously while they worked correctly the last use would be extremely unlikely.

 

[panamaguy]

I tested my 40 today and it won’t move the blade or the boom swing with the safety lever up which I didn’t think it would. I’d feel pretty confident the safety mechanism is messed up. Hydraulic pumps don’t usually fail all at once. The chance of multiple pumps failing all at once simultaneously while they worked correctly the last use would be extremely unlikely.

I tested my 40 today and it won’t move the blade or the boom swing with the safety lever up which I didn’t think it would. I’d feel pretty confident the safety mechanism is messed up. Hydraulic pumps don’t usually fail all at once. The chance of multiple pumps failing all at once simultaneously while they worked correctly the last use would be extremely unlikely.

Well i know mine failed all at once. Worked all on day. Loaded the machine, came home unloaded and parked it under cover. Went out in the morning and fired it up. Lifted the boom and swung it 180 degrees, lifted the blade and backed it out. Dropped the blade to lift the machine as i was going to wash it. Centered the boom and set it down only to find out it would not lift the machine. Naturally we hope and pray thatvitvis a cheap fix and so did i. Tore apart the safety armrest first andcthen started on different valves. And in the end found the first 2 sections of my Nachi pump had failed. Still had the 3rd section thus the blade, track extension and swing. And the 4th is the pilot. But the 1st two that work in tandem died. I hope he finds a easy fix but now that I just did mine a month ago i think he might find the same. I hope he tries pushing the 2 travel levers just a little forward and at the same time tries lifting the boom. That would tell him 100 % if partvof his pump failed like mine

 

[Seven Gables]

The thing on a 121 is that although most of the controls are pilot valves, a few are not and are mechanically locked in position when the safety lever is up. This is definitely true for the track controls, but I can't remember for others.

So if the safety lever is down and the pilot controlled functions don't work, but the non-pilot valve functions do work, then there is an issue in the pilot control system, not the main hydraulics.

I agree with 4570 very good odds it’s a fault with the pilot lockout system. However if we take the OP’s description literally at his word that “nothing works “ including the mechanically operated functions there must be another issue.
These mechanically operated functions are not locked out with the pilot lockout system, only the pilot operated valves are prevented from working. As Hayden says in his post above at least some of the mechanically operated functions are locked out mechanically with the safety lever up , so it would still have to be in the down position.
On 4570’s newer 040 machine all functions are pilot controled (no mechanically operated valves) and therefore all are locked out with the pilot lockout system when safety lever is raised.
If the Op is correct that ALL functions do not work including the 2or 3 mechanically controlled valves that are not locked out with the pilot lockout system it would indicate that something besides the pilot lockout system is at fault. Could be the the engine to pump coupler let go which would definitely shut down All functions as the Op claimed.
Wish the op would give us some more info like how many hours the machine has or if he actually tested ALL functions

 

[4570Man]

I agree with 4570 very good odds it’s a fault with the pilot lockout system. However if we take the OP’s description literally at his word that “nothing works “ including the mechanically operated functions there must be another issue.
These mechanically operated functions are not locked out with the pilot lockout system, only the pilot operated valves are prevented from working. As Hayden says in his post above at least some of the mechanically operated functions are locked out mechanically with the safety lever up , so it would still have to be in the down position.
On 4570’s newer 040 machine all functions are pilot controled (no mechanically operated valves) and therefore all are locked out with the pilot lockout system when safety lever is raised.
If the Op is correct that ALL functions do not work including the 2or 3 mechanically controlled valves that are not locked out with the pilot lockout system it would indicate that something besides the pilot lockout system is at fault. Could be the the engine to pump coupler let go which would definitely shut down All functions as the Op claimed.
Wish the op would give us some more info like how many hours the machine has or if he actually tested ALL functions

I don’t think the boom swing or blade lift on my machine are pilot operated. They seem firm like an actual hydraulic valve. And the track levers are almost definitely not pilots.