Kubota B7100 Bucket Drops within 5 minutes

[Spencer_4-hire]

Hello,

New land owner and just bought my first tractor. Did a lot of reading on this site and ended up purchasing a '94 Kubota B7100 HST with 500 hours.

The tractor shows little use and appears to be in excellent mechanical condition, however I discovered an issue that I need assistance to diagnose and repair.

When I set the bucket tilted up, within 5 minutes it is dropped down to facing forward. Also the height has dropped a bit, but mostly an issue with the tilt. I believe this is an internal hydraulic leak, but is it in the cylinders, control valve, or ?

How does one go about pin-pointing the source of this issue?

Thanks so much.
Spencer

 

[J_J]

Hello,

New land owner and just bought my first tractor. Did a lot of reading on this site and ended up purchasing a '94 Kubota B7100 HST with 500.

The tractor shows little use and appears to be in excellent mechanical condition, however I discovered an issue that I need assistance to diagnose and repair.

When I set the bucket tilted up, within 5 minutes it is dropped down to facing forward. Also the height has dropped a bit, but mostly an issue with the tilt. I believe this is an internal hydraulic leak, but is it in the cylinders, control valve, or ?

How does one go about pin-pointing the source of this issue?

Thanks so much.
Spencer

Spencer,

It all depends on if you are mechanically inclined. If not, I would remove the valve take it to a hyd shop, and if it test good, then take the cylinders. The other way is to purchase a gage and use it to test the pressure at good locations where there should be tractor operating pressure. The lift and tilt dropping is probably caused by fluid flowing out of the cylinders back to the tank through the valve. $45 to $60 will get you about an hour of hydraulic service, testing cylinders, and valve, etc. If you know about how hyd fluid works, you can use logical trouble shooting procedures to isolate the trouble. If it's gummed up, a good cleaning might help. If it's worn out or broke, repair or buy new stuff.

 

[Ken Cunningham]

Assuming you have quick connects, you could unhook the lines once you have it up and if it does the same thing then the piston seals are bad in the cylinders. If it doesn't then have the valve looked at. Your gonna have to have a way to relieve the pressure off the line to rehook them, so plan ahead. If you only leave it a little off the ground put a jack under it to make hooking back up easier.

 

[Spencer_4-hire]

Thanks for the advice. Unfortunately, it does not have quick connects, so I will proceed to remove and clean the control valve and see if that helps correct the issue.

After R/R on the control valve, is there any bleeding procedure that needs to be followed when reassembled, or are the hydraulic lines self bleeding and I just need to verify fluid level?

Also planning on changing the Hyd fluid soon. Would you guys recommend I use Kubota UDT, SUDT, or TSC Hyd fluid or ? .

Thanks,
-Spencer

 

[Ken Cunningham]

You will have to cycle the hydraulics a few times to get the air out, but the air will follow the fluid back to the tank. So no bleeding of the hyraulics

I just thought of this so:
What about if you raise the bucket and then lossen the line that returns to the tank, if fluid keeps oozing out the that would show the valve to be bad, and if it doesnt then its the seals in cylinder.

 

[art]

Do not take off the valve! 95% of the time it's the packings in the cylinder.

A simple test we do is to roll the bucket back, remove or loosen the hydraulc line on the opisite of the cylinder from the pressure port that filled the cylinder. If it leaks out then it's the packings. To do one you might just as well do both!

 

[Bird]

My 1995 B7100 had the same problem; maybe even worse, while it was still in warranty. When I was mowing or tilling, every few minutes or less I'd have to raise the FEL. The dealer first tried "rebuilding" the cylinders and when that didn't help, all 4 cylinders were replaced under warranty. And that fixed it.

 

[Wayne County Hose]

I will bet that at least 25 cylinders have a problem to every valve problem. I would not hesitate to rebuild the cylinders without even checking the valve.