B7100 lift arm issue

[stig]

Hi guys, I hope you can offer some advice for an issue I've got with my B7100D.

Basically, the only way of keeping an implement 'raised' with the hydraulic control lever (which controls the lift arm), is to hold it in the 'raised' position. So the valve/seal/o-ring(?) that stops the leakback of the hydraulic oil doesn't seem to be working?

If I raise an implement - say - half way, it will drop back to the ground of its own accord very quickly. The only way I can get it to stay 'up', is by holding the control lever in the 'up' position - which obviously isn't great because the pump is having to work the whole time to keep it there!

Any ideas?

Thanks

 

[Bird]

And the pump working to keep the arm up is also probably keeping the relief valve open, so you need to fix the problem right before you have more problems.

 

[mwb]

Is the control lever falling back down because it is not tight enough? Sounds like it if you have to hold it up. The lever should stay in place where you leave it; there is probably an adjustment to tighten the lever so it stays in place. If your tractor is labouring or the relief is going then that is a different problem.

Maybe the parts manual would help?
Index of Kubotabooks/Tractor Parts Manuals/

 

[charlz]

Most likely you need to replace the o-ring in the 3pt lift cylinder. Fortunately not only is this a cheap and easy fix but I also documented it when I did mine:

http://www.tractorbynet.com/forums/parts-repairs/88048-repair-kubota-b7100-dropping-3pt.html

 

[stig]

Most likely you need to replace the o-ring in the 3pt lift cylinder. Fortunately not only is this a cheap and easy fix but I also documented it when I did mine:

http://www.tractorbynet.com/forums/parts-repairs/88048-repair-kubota-b7100-dropping-3pt.html

Great - thanks Charlz!

I don't suppose you have the part numbers for the bits you need?

 

[allenr]

Is the control lever falling back down because it is not tight enough? Sounds like it if you have to hold it up. The lever should stay in place where you leave it; there is probably an adjustment to tighten the lever so it stays in place. If your tractor is labouring or the relief is going then that is a different problem.

Maybe the parts manual would help?
Index of Kubotabooks/Tractor Parts Manuals/

The 7100 doesn't have a position control TPL. It works more like a spool valve for a loader but with a detent in the raise and lower positions.

 

[charlz]

04810-08500 o-ring for piston
04811-50550 o-ring for cap

There is another little o-ring under the cap but I don't know the part number for it, I didn't buy it originally and just went and bought one from a hardware store when I figured out I also needed it. Dealer should be able to figure it out.

 

[stig]

04810-08500 o-ring for piston
04811-50550 o-ring for cap

There is another little o-ring under the cap but I don't know the part number for it, I didn't buy it originally and just went and bought one from a hardware store when I figured out I also needed it. Dealer should be able to figure it out.

Thanks Charlz - the part number of the little one is 04811-00080

 

[IL4now]

FYI...just replaced mine last weekend and followed the instructions on the link above.

However, I didn稚 have a magnet strong enough to pull the piston out. I was able to remedy this situation by the following:

I disconnected the stoppers (I don稚 know the correct name), but they stop the 3PT hitch from going up or down to far. Now I was able to raise and lower the 3PT hitch by hand to the max. I raised it all the way so the piston was at the top. I then slowly lower the 3PT hitch so the piston stayed near the top. You can稚 see this, but the rod then drops down (see pic) and when I raised it back up the rod pushes the piston out into my hand.

I know it sounds confusing, but I was able to complete the whole process in 2 hours without any technical skills

 

[Andy JH]

I just replaced the 3pt lift piston o'rings on my B7100 and the drooping lift is gone. Used IL4now's method of getting at the piston as I didn't have a magnet either.

Want to thank charlz for a brilliant post and excellent pictures.

I sourced the O'rings through a local seal specialist. Total cost was AU$ 3.65, and a skinned knuckle, which sure beats the hundred of so quoted.