I have a Kubota KX121-2 mini excavator that is having some hydraulic problems. It was working fine and it sat for 3-4 months. Then I started it back up and the main hydraulics do not work. ( tracks, boom and bucket) The secondary pump that runs the blade and turntable work well. we noticed a hissing/air sound on startup for few second and hydraulics work for mere seconds then it stops completely. sometimes hear bubbles or air in the hydraulic tank ( tank is slightly overfilled) On the KX121-2 there is very little electronics compared to my KX121-3( newer model) It seems like there is a main relief valve stuck open, allowing fluid toflow back into the tank at a high rate ? Hydraulics are my weak spot..... Has anyone had a similar issue ? Thanks Don
Good day Dh I taken a look at the schematic and those circuits you are missing is protected by the same relief valve it would seem that from the description your diagnostics are correct, the other circuits according to my schematic are serviced by the same pump with split flow, that being the case it is unlikely that the pump is the issue. I suggest remove and inspect the relief valve. Kind regards Uffex
Does anyone know how to identify which ones are the relief valves? I mean which one specifically? The 2 lines come in that feed the valve body each one has a relief valve near it. Are those the ones? Or is there something near the return?
If anyone knows the path hydraulic fluid takes through the valve body and which relief valves control the right side lemme know. I swapped the 2 main ones and still it feels like the right side pressure relieves. Only works when I use stick in combo with boom or curl. Could it be that the piston pump is not building enough pressure on those pistons?