Anyone have any ideas on why my Kubota SVL 90-2 lift arms wont stay up. I was using a brush cutter and it still works but my lift arms will not stay up. I removed the cutter and the loader arms will not stay up, it will lift the arms but they drift all the way down. I am not getting any codes. Any help will be greatly appreciated.
Sounds like you might need to replace the seals in the cylinders. I am not very familiar with your machine but if mine was doing this, that is where I would start.
I'd be curious to know whether the boom can hold the weight of the machine. Place the bucket on, curl the bucket all the way down (open), and boom down to lift the front of the machine. If the front of the machine stays lifted up, the boom up relief cartridge is suspect. If the boom drifts up (machine settles to the ground), then one of the hydraulic cylinder piston seals is suspect.
I raised the boom up and then tilted the bucked down and it drifts down and lifts up the machine in the front and holds it up (does not drift). With the boom lowered I curled the bucket and it holds the machine up and stays up (does not drift).
Sounds like the valve is being stroked in the down position either spool leakage or pilot pressure in down position...
Leaking spool in the joystick, leaking spool in the directional control valve or plugged drain passage in the control valve.
Either a spool cap has come loose (050 or 060), or a relief cartridge (550) is compromised. After ensuring that boom can't fall, the two 550 relief cartridges can be alternated.
Possible issue with something in the control valve. I would check the centering springs on the boom control spool. Its also possible for a small piece of cylinder packing in the control valve hanging things up as it floats around.
I will post what I find, it may be a few days before I can get too it. thanks to all for your input.
It ended up being one of the overload relief valves in the lift arm section of the control valve assembly. Thanks again for your help I appreciate it.
Does anyone know if the overload relief valve can be rebuilt. The cost is $588, part # V0511-63640.
They can be disassembled and inspected. Based on your symptoms, I'd suspect debris in the seat area. On my Cat excavators, the relief valve assy has an integral makeup valve, and, the makeup valve spring can get unravelled into the relief seat. On them, I just flip the spring over and put it back together. If you mark and index the valve's nuts and count threads, you can put it back together and be amazingly close to the original setting.
I took it apart and cleaned it, it did not help it so I exchanged it with the one on the downward bucked. The control arms are working as they should. But now when I take the bucket to the down (dig) position and when I release the controls it will drift to the level position. I can live with it for now. Thanks for your help.
Could you possibly have taken the wrong one apart? You disassembled, cleaned, and reinstalled one, and saw no change. You then swapped them and the problem moved.
That could be a possibility. you gave me something to think about. I will post any changes I find. Thanks
After running it for a while it cleared up and all is working like it should, must have been something in the valve.
can the relief cartridges be adjusted? I am wondering what there adjustment is for. I am having this same problem. Removing the cartridges I started with the nut on the threaded shaft and then realized that was for adjustment, But what does it adjust?
I swapped mine yesterday and am still having the same problem. WHat are items 50 and 60 you noted? How do I check to see if they are loose as you mentioned?
There are 2 of the 550 relief cartridges, you could count the threads that are exposed and set the other one to match it . They should be set the same. If you swapped one 550 with another 550 and it did not change then your problem is not in the 550.