Good morning all, Working with a 2006 Kubota KX161 (4,300 hrs), 5.5 ton machine. Flow tube on the side of the thumb cylinder was damaged, ended up cutting damaged tube off and TIG'ing new tube to cylinder barrel. While cylinder was apart, I rebuilt it with an OEM seal kit (ordered from Kubota, seal kit was from Rosenboom). New fittings and two new rubber hoses connecting cylinder to metal lines on dipper arm. Once everything was back together, thumb worked great. After about 2 hours of operating and moving some small boulders on the property, I blew the rubber hydraulic line for the thumb that connects the main boom to the dipper. This is on the return side. Once I had it off, the hose was badly dry rotted. I may have overpowered the thumb with the bucket. Ended up replacing both hoses as they appeared to be the originals. They're covered ion a metal spring for protection and kinda makes it hard to inspect them. All back put together, topped my hydraulic oil off and got everything bled out. Cylinder moves smoothly but seems to drift on me now. If I'm closing the thumb and let off on the button, the cylinder will drift down a few inches before stopping. While digging, every few minutes, I'll have to retract the thumb to get it back out of the way. It won't close completely, but slowly fall. If I retract the thumb, once I let go of the button, it will drift down a few inches and stop. If I park the machine and retract the thumb all the way back, once it drifts down a few inches, it will stay in place. Park it overnight and the thumb stays up. No leaks from the cylinder. Again, probably 2 hours on a cylinder rebuild before the hose bust and this drifting started. Ran the machine about another 5 hours since. Seeking some guidance on troubleshooting at this point from the wise forum members. Should I break the cylinder back down and inspect the seals? Valve block?
No replies yet.