BT650 boom won't lift

haroldeveryman

New member

Equipment
B20
Aug 13, 2017
7
1
3
ny
After finally conquering the swing problem, I now have another serious problem. I used the backhoe a few times this past summer and all was well. Saturday I took it out of the barn to dig a few holes and found it impossible to remove the safety boom-lock pin. Normally I just pull back on the boom control to take the pressure off but this time it failed to work. I put a floor jack under the bucket and lifted the boom and then was able to remove the pin. However, when I lowered the jack the boom came down a few degrees, then held the position. When I moved the boom control down it went down fine but it failed to return so I used the jack to lift it back and put the pin in.

When I move the boom control to the down position with the pin in place I can hear the hydraulics straining and I can see the boom straining against the pin so I assume that the problem is not in the boom cylinder.

I then decided to make a final test to see that the cylinder is OK. I swapped the hose from the dipperstick control with the boom control and I was able to both lower the boom and raise it again by manipulating the levers. Conclusion: something is wrong with the control valve. The cylinder is OK.

I plan on disassembling the valve body in a few days but would like any thoughts on the problem before I dig in. All input is appreciated.
 

haroldeveryman

New member

Equipment
B20
Aug 13, 2017
7
1
3
ny
Problem solved. From the number of replies I got to my problem I assume there are no other Kubota B20 owners with a bt650 or bt750 backhoe. Just in case someone in the future has a similar issue I will post the solution here:

On the bottom of the control valve section that controls the boom up and down, there is a cap which is held on with two Allen-head screws. Removing that cap revealed a small amount of crud (rust and corrosion) in the bottom of the cap. There was not a lot but enough to prevent the spool from moving down all the way. I cleaned the crud out of the cap and reassembled the valve and hoses and the problem is gone.

So, for all three owners out there of a B20 with a bt650 backhoe, that is the answer.