Kubota BH90 Valve Problem

[kubotam125xoklahoma]

Hey guys,
Have a problem with my Kubota BH90 Backhoe. The problem lies within the 2nd valve from the left hand side looking at it from the rear. In the following picture, 3rd section from the left. It is leaking from the spool on the bottom and I have no flow going to the cylinder in the down position. Up however, works fine. By down I am referring to, when sitting in the operator stanchion, pushing to dipperstick lever away from you and by up I mean pulling it toward you. Problem is in dipperstick valve only. Now, I have taken it all apart, except for the spool, and replaced the o-rings between the stacks and the o-rings in the relief valves to no avail. Kubota wants 600 dollars for the rebuild kit for the spool in that valve and 1200 for a whole new valve. I can't spend that much. Any suggestions?

 

[DiskDoctr]

I have no flow going to the cylinder in the down position

Welcome!

Curious how you tested for flow? Are you sure the outlet, hose, and cylinder aren't to blame?

I wanted to get you a quick reply so you know we're looking at your post. Some hydraulics experts will likely post shortly.

- JC

 

[kubotam125xoklahoma]

Welcome!

Curious how you tested for flow? Are you sure the outlet, hose, and cylinder aren't to blame?

I wanted to get you a quick reply so you know we're looking at your post. Some hydraulics experts will likely post shortly.

- JC

Thanks for the reply. :thumbsup: Oh sorry, let me clarify about how I tested for flow... I was just going off of the cylinder not retracting when I push the lever forward. I didn't check for flow from the valve. To do that, would I just remove the two hoses from that valve, start the tractor, and see if any fluid squirts out when I push the lever away from me? I assume everything is fine with the hose, and cylinder as the dipperstick section works perfect when I pull the lever toward me. However, per your suggestion, I will go hook that cylinder and its hoses up to another valve and test them, will report back. Also, I did take both lines off the cylinder and blew them out with compressed air, no obstructions.

 

[DiskDoctr]

I will go hook that cylinder and its hoses up to another valve and test them

Much better idea than squirting >2000psi hydraulic fluid. A bit cleaner, too

When you replace the o-rings, how were the old ones? Any pieces of the o-ring missing or broken? See any scoring of the components?

Sure you put it back together correctly? (Not being smart, it happens).

- JC

 

[kubotam125xoklahoma]

Much better idea than squirting >2000psi hydraulic fluid. A bit cleaner, too

When you replace the o-rings, how were the old ones? Any pieces of the o-ring missing or broken? See any scoring of the components?

Sure you put it back together correctly? (Not being smart, it happens).

- JC

Cylinder works perfect, I just swapped hoses with the bucket curl valve. The dipperstick valve is the culprit I think, as it did the same thing when hooked to the bucket curl cylinder. Oh, I should also add that the valve leaks too, from the spool cap that is secured by the 2 hex screws.

O-rings were perfect. Everything looked great.

Yes, the problem started before I replaced the o-rings and the problem still exists after re-assembly. I should have worded that better... I replaced the o-rings in an attempt to fix the problem, the problem did not start because I put it back together incorrectly.

Thanks for your help, keep it coming :thumbsup:

 

[DiskDoctr]

Wish I had more for you. You've been pretty thorough responsive with your tests and answers.

At this point, instead of confusing things by suggesting tests that may not be the most diagnostic, I'll pause and we'll wait for some of the experts to weigh in. I think the info is set up for some good feedback.

- JC

 

[kenstrac]

Hey guys,
Have a problem with my Kubota BH90 Backhoe. The problem lies within the 2nd valve from the left hand side looking at it from the rear. In the following picture, 3rd section from the left. It is leaking from the spool on the bottom and I have no flow going to the cylinder in the down position. Up however, works fine. By down I am referring to, when sitting in the operator stanchion, pushing to dipperstick lever away from you and by up I mean pulling it toward you. Problem is in dipperstick valve only. Now, I have taken it all apart, except for the spool, and replaced the o-rings between the stacks and the o-rings in the relief valves to no avail. Kubota wants 600 dollars for the rebuild kit for the spool in that valve and 1200 for a whole new valve. I can't spend that much. Any suggestions?

This might be the problem the spool O-rings were not changed?

 

[J_J]

Do you have the same travel on the lever in both extend and retract? The problem almost has to be in the spool, perhaps the spool is not moving enough to allow fluid to flow. Parts could have come loose on the bottom of the valve jamming things. That second valve looks like part of a joystick lever, and some parts may be worn. Look at the spool as you move the lever and see if the spool pushes in the same as pulling out.

 

[kubotam125xoklahoma]

This might be the problem the spool O-rings were not changed?

I think you may be right... I would have purchased new O-rings for it, but they were extremely expensive, like I think 2 o-rings were $190 dollars on their parts breakdown picture of the valve. I wonder if they would be readily available sizes? I will be disassembling it again today, this time removing the spool cap and inspecting internal o-rings, I guess I will find out then! Thanks to all for the continuing assistance.

 

[kubotam125xoklahoma]

Do you have the same travel on the lever in both extend and retract? The problem almost has to be in the spool, perhaps the spool is not moving enough to allow fluid to flow. Parts could have come loose on the bottom of the valve jamming things. That second valve looks like part of a joystick lever, and some parts may be worn. Look at the spool as you move the lever and see if the spool pushes in the same as pulling out.

Yes, from what I can tell it moves the same distance as it always has, so I think everything is in one piece. The more I think about this, the more I think it is an internal o-ring problem, in the spool. Yes I think it is just wore out. The unit only has 450 hours. I have used the piss out of this backhoe since new on my ranch, I guess I need to buy an actual excavator from CAT or Deere that will be reliable.. Thanks for the continuing assistance.