B7100 Hydraulic Help Needed

[gobux3]

Alright guys,



Need some help to get my B7100 hydraulics working the way they should after adding a new (to me) loader. I’ve read everything I can find on this forum (and others) on the topic, and while it’s been a great help in getting me to this point, now I’m stuck. I’m going to spell out steps in detail in hopes that it will help diagnose the issue.



1. Added Kubota factory diverter block to tap into integral tractor hydraulics. Original o-rings on diverter block looked ok so I reused them.

2. Plumbing: a) diverter block to loader inlet b) loader outlet to hydraulic reservoir c) loader Power Beyond back to diverter block (to send fluid to 3PH)

3. Loader works, hooray! Worked loader cylinders to displace air & added Kubota hydraulic fluid back to appropriate fill level

4. Uh oh, 3PH doesn’t work – didn’t realize a special adapter was required to tap the Power Beyond port, so when I originally plumbed it this way, I only had “return” flowing back to 3PH, and 3PH obviously would not operate. In the immediate aftermath, I did the following (listing in case these things could’ve caused damage)

a. Swapped PB & Return line

b. Rotated “selector” handle for 3PH auxiliary function (located directly in the front of the seat)

5. Time to get to work – despite not being able to put any weight on the rear end without 3PH function, I proceed to move and grade 45 yards of topsoil. No Power Steering is a PITA, and it’s hard to keep the rear tires on the ground at times, but it gets the job done.

6. I finally receive & install correct power beyond adapter from manufacturer of loader spool valve (Metro). Now I can feel pressurized fluid coming through the PB hose, however 3PH still won’t lift?! In an attempt to troubleshoot, I do the following:

a. Run a “jumper hose” across the diverter block, directly connecting the inlet & outlet, while completely removing all loader connections from the hydraulic system. Start the tractor and 3PH raises immediately. I lower it, and it won’t raise back up. Check hydraulic fluid & add to full. Still no lift.

b. Manually raise and lower 3PH arms while trying to actuate cylinder in hopes of working any air through the system. No luck.

c. Thinking I may have somehow caused an issue with the pump, I plumb the loader back into the system and it still works like a charm.



And that’s where I sit. My thoughts on next steps are 1) closely investigate the entire system for a leak somewhere in daylight 2) go back to 100% factory setup (pass-thru diverter block) to eliminate the possibility of a faulty quick connect somewhere. Please let me know where I screwed up or what to look for next! Really worried that somehow I damaged the 3PH, although I don’t see how that could’ve happened.

 

[North Idaho Wolfman]

Check the position of the valve under the seat, sounds like you have that in the wrong position.

Pulling up on the three point arms does nothing as the cylinder for the three point is not hard coupled to the linkage so that it can float.

You've cut off fluid to the three point in some way.
If it worked before you altered it it will work again.

On the loader valve, no fluid should flow out of the Tank (return port) until either the loader valve is used to the point where it trips the internal relief valve or there is a blockage on the PB port.

 

[fender76]

Assuming your loader is using the tractor hydraulics and the factory diverter valve you should not need the power beyond port. Use an open-center valve, go from the front opening on the diverter valve to the inlet port of the loader valve, then from the return port on the loader valve body, go back into the rear opening on the diverter block. This way you do nothing with the valve under the seat, or with the fill port.

This is how I plumbed my front blade, and either the front hydraulics or the 3-point can be used without switching anything.

 

[100 td]

Recheck hose connections, you state you swapped PB and return hoses to get it working before installing PB adapter. Ensure delivery from block to inlet on loader, PB from loader valve back to block.

Check per page 302 of the pdf here.
http://kubotabooks.com/AutoIndex/index.php?dir=Tractor%20Owners%20Manuals/&file=B7100HST_WSM_complete.pdf

 

[torch]

a. Run a “jumper hose” across the diverter block, directly connecting the inlet & outlet, while completely removing all loader connections from the hydraulic system. Start the tractor and 3PH raises immediately. I lower it, and it won’t raise back up. Check hydraulic fluid & add to full. Still no lift.

Ok, at this point you are basically back to factory original and the loader is completely out of the circuit.

When you say "start the tractor and 3ph raises immediately", do you mean that literally? It raised without operating the lever? Or do you mean that it worked right away when you operated the lever?

I would start with the simple stuff: check the position of the diverter valve under the front of the seat and the sliding stops on the lift lever interlock rod. This sounds like it could be a mis-configuration issue.

The only other thing I can think of is that some debris entered the system during installation of the FEL hydraulics and entered the 3ph relief valve when that piston hit the end of it's travel and is now stuck in the relief valve seat, holding it open. That would explain why it worked once and never thereafter.

 

[gobux3]

All,

Thanks for the ideas and recommendations. Had a chance to jump back on it tonight and determined the root cause. I replaced the factory diverter block (pass thru) and 3ph worked perfectly, which told me there was an issue with the block, jumper hose or quick connects. I isolated each component until I discovered that I had a faulty female quick connect that was restricting flow significantly.

Plumbed that connection direct with NPT in the short term, and everything functioned perfectly.

Thanks again!

 

[Lil Foot]

Glad to hear you got it resolved, and thanks for posting your results!

 

[matski]

Assuming your loader is using the tractor hydraulics and the factory diverter valve you should not need the power beyond port. Use an open-center valve, go from the front opening on the diverter valve to the inlet port of the loader valve, then from the return port on the loader valve body, go back into the rear opening on the diverter block. This way you do nothing with the valve under the seat, or with the fill port.

This is how I plumbed my front blade, and either the front hydraulics or the 3-point can be used without switching anything.

What exactly is the front and back? Just so I'm sure I'm doing it the same... any pictures?

 

[TheOldHokie]

Check the position of the valve under the seat, sounds like you have that in the wrong position.

Pulling up on the three point arms does nothing as the cylinder for the three point is not hard coupled to the linkage so that it can float.

You've cut off fluid to the three point in some way.
If it worked before you altered it it will work again.

On the loader valve, no fluid should flow out of the Tank (return port) until either the loader valve is used to the point where it trips the internal relief valve or there is a blockage on the PB port.

Return is also used for exhaust oil from the cylinders. For a typical valve when you operate the loader there should be oil flowing out tank return and none on power beyond.

Dan

 

[TheOldHokie]

What exactly is the front and back? Just so I'm sure I'm doing it the same... any pictures?

Do not follow that advice. The tank port is not designed for the hydraulic pressure the 3pt will generate. A typical tank port is limited to ~500 PSI and exceeding that can damage the valve. For high-pressure carryover you need to isolate tank from power beyond.

Dan

 

[matski]

Do not follow that advice. The tank port is not designed for the hydraulic pressure the 3pt will generate. A typical tank port is limited to ~500 PSI and exceeding that can damage the valve. For high-pressure carryover you need to isolate tank from power beyond.

Dan

I'm not the most knowledgeable when it comes to terminology. Are you saying that the adapter block method is the only way to use the loader and 3pth?

 

[TheOldHokie]

I'm not the most knowledgeable when it comes to terminology. Are you saying that the adapter block method is the only way to use the loader and 3pth?

I am saying this advice about power beyond is wrong and can cause damage to your machine. You need to use a valve with power beyond.

Assuming your loader is using the tractor hydraulics and the factory diverter valve you should not need the power beyond port. Use an open-center valve, go from the front opening on the diverter valve to the inlet port of the loader valve, then from the return port on the loader valve body, go back into the rear opening on the diverter block.

Your original plumbing using the outlet block, a valve with power beyond and a separate tank return is the connection method Kubota intended. It protects the pump and valve from damaging overpressure conditions. I don't know exactly what you had wrong but the plumbing was basically correct. Go back to it. It will allow you to use the loader and 3pt without any need to switch back and forth.

Dan