Kubota LA 401 FEL Won't go up!

   / Kubota LA 401 FEL Won't go up! #1  

Girtski

New member
Joined
Sep 19, 2011
Messages
15
Tractor
Kubota B2710
Second post new member here.

I have a B2710HST with an LA401 loader with 4 position valve. Never has my loader bucket raised consistently to the prescribed height. Occasionally it would, but mostly it only went up about 3 feet until recently. It now only raises about 10". I changed the transmission fluid from Super UDT to Super UDT2, changed the spin-on hydraulic filter, cleaned both screens (which were not at all dirty). None of this made any difference in the height. It sounds and feels like it's reached it's limit when I raise the bucket.

If I take the hoses off and put them on the curl/dump side, the bucket raises full travel and lowers fine. I replaced both detents with new kits a couple years ago because they were sticky and rusted. That made no difference at the time.

I've read where the quick-couplers could cause problems so I swapped them from side to side to see if that would make any difference. It did not.

What I did discover when taking out the quick couplers was that the top port in which the coupler screws on the lift side has no holes in it. It's a dead port. I'm wondering if this is normal? If so that would only leave one port for raising and lowering. Since there is no hole for oil travel I suspect this to be normal or the bucket wouldn't work at all. I would love to see a hydraulic schematic showing the fluid flow during lift and drop activity.

Can anybody give me some tips on things to try next? Although not a hydraulic specialist by any means, I am a mechanic by trade and do not understand why I have intermittent operation and now am only limited to 10" of lift.
 
   / Kubota LA 401 FEL Won't go up! #2  
Second post new member here.

I have a B2710HST with an LA401 loader with 4 position valve.
Welcome, I have the same machine.
If I take the hoses off and put them on the curl/dump side, the bucket raises full travel and lowers fine.
Did the curl/dump function work when switched?
 
   / Kubota LA 401 FEL Won't go up!
  • Thread Starter
#3  
Welcome, I have the same machine.

Did the curl/dump function work when switched?

No..It would work partially one way and fully the other depending on which port I put the hoses on the lift side.
 
   / Kubota LA 401 FEL Won't go up! #4  
I have the loader shop manual but am not very good with hydraulics. There are two kind of valves, a 3 position and a 4 position bucket control. That might explain why you see one port that appears blocked. I would guess from what you've described that the spool is bad for the boom function. Hopefully someone more knowledgeable will chime in.
 

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