B6100 3pth leaking down

[Brushwacker]

Hi all,
My newly aquired B 6100 raises the 3pth nicely but will not hold the impliment up.. any ideas? I'm not opposed to tearing into a hydro valve if its just some o-rings. thanks

 

[Piker]

Just replaced the O ring & backup washer yesterday (also cover O ring) on the piston in the hydraulic cyl. under the seat on my 1980 B7100. All winter it would hold up a heavy (app 400lbs) 4' blower for about 4 hrs. But as the temps. warmed up it would only hold my back blade (app 200lbs) about 2 hrs. After O ring replacement it now takes about 4 hrs. for the back blade to drop. Bore of cyl. was smooth with no nicks or grooves. Piston fit much tighter with new O ring - piston & old O ring popped out easily when I quickly raised the rear lift arms. When I have more time I might remove the spool that the control lever operates & have a look. Manual doesn't show any O rings on it to replace. It will be plenty fine for working as-is.

 

[Brushwacker]

thanks for the replys guys.. piker could you describe the procedure a little better? I don't have a service manual.

 

[Brushwacker]

OK today was the first time I've worked the tractor for any length of time..I graded my 1000' driveway which gave the little guy a workout. I noticed the 3pth WILL hold up the blade if you wiggle the lever a bit. If you don't then the grader will almost immediatly fall. Is there somthing to adjust/replace on the valve etc ?? thanks

 

[Piker]

On my 1980 B7100 there was a missing ball bearing (internally) that provides a detent for the hyd. control lever in the neutral/centered position - rather than having gravity/vibration cause the lever to fall & the 3 point to lower. Here is a link to some free manuals - http://www.kubotabooks.com/AutoInde...s/&AutoIndex=320d729de9fb03538c9d6e8aec0f847c
The cyl. & piston for the hydraulics is under your seat, behind the trans. shift lever. There is a bracket attached to the trans. & the front cover. Remove 6 bolts & the cover/diverter valve will pull straight out (don't pry sideways to remove as the cover extends into the cyl. & has an O ring to seal it). The top of the piston is what you're looking at with the the cover off & will move when you raise/lower the lift arms. My O ring on the piston was compressed enough that the piston moved easily in the cyl. & popped up far enough (by raising lift arms quickly) so I could get a grip on it & pull it out. Install new O ring & backup washer, lube it with hyd. fluid & slide it back in. Less than 1 hr. job.

 

[Brushwacker]

On my 1980 B7100 there was a missing ball bearing (internally) that provides a detent for the hyd. control lever in the neutral/centered position - rather than having gravity/vibration cause the lever to fall & the 3 point to lower. Here is a link to some free manuals - http://www.kubotabooks.com/AutoInde...s/&AutoIndex=320d729de9fb03538c9d6e8aec0f847c
The cyl. & piston for the hydraulics is under your seat, behind the trans. shift lever. There is a bracket attached to the trans. & the front cover. Remove 6 bolts & the cover/diverter valve will pull straight out (don't pry sideways to remove as the cover extends into the cyl. & has an O ring to seal it). The top of the piston is what you're looking at with the the cover off & will move when you raise/lower the lift arms. My O ring on the piston was compressed enough that the piston moved easily in the cyl. & popped up far enough (by raising lift arms quickly) so I could get a grip on it & pull it out. Install new O ring & backup washer, lube it with hyd. fluid & slide it back in. Less than 1 hr. job.

Hey Piker great advice!, I did the job today and the 3pth is still holding up the blade. the only thing I had to do different was to use a strong magnet to help pull the piston out of the cylinder..the hydraulic shop in town had the Oring on the shelf too. Whole job including going to get the parts was under 2hrs.

 

[Dennis]

On my 1980 B7100 there was a missing ball bearing (internally) that provides a detent for the hyd. control lever in the neutral/centered position - rather than having gravity/vibration cause the lever to fall & the 3 point to lower. Here is a link to some free manuals - http://www.kubotabooks.com/AutoInde...s/&AutoIndex=320d729de9fb03538c9d6e8aec0f847c
The cyl. & piston for the hydraulics is under your seat, behind the trans. shift lever. There is a bracket attached to the trans. & the front cover. Remove 6 bolts & the cover/diverter valve will pull straight out (don't pry sideways to remove as the cover extends into the cyl. & has an O ring to seal it). The top of the piston is what you're looking at with the the cover off & will move when you raise/lower the lift arms. My O ring on the piston was compressed enough that the piston moved easily in the cyl. & popped up far enough (by raising lift arms quickly) so I could get a grip on it & pull it out. Install new O ring & backup washer, lube it with hyd. fluid & slide it back in. Less than 1 hr. job.

Thanks Piker,
did the job on a B7100 today. My rota cutter would not hold up for 20 seconds and now it stays up fine.

For others contemplating , just some comments on the job: The piston may or may not be near the top of the cylinder when you take the cover off; I found that if I lowered the arms completely to the ground (before dismantling) the piston seemed to be pressured to near the top of the cylinder.

I had to raise/lower my lift arms rapidly about 20 times until the piston edged itself out far enough out to get a grip and pull it completely out. If it slips back down, do some more cranking on the arms and it will return.

Finally, be prepared for some oil spilling out when you remove the cover. Rags and an oil drain tray underneath the tractor to catch the spill.