Hello, i need little help with problem iam dealing with right now. I have for repair 988 K loader with low power on implements. Lift and tilt is weak and sometimes slow. Also sometimes its not smooth when lifting with load, its kinda jumping, like the pump does not delivere enough flow. We checked pressure and that is what does not make sence to me. On idle is like 330 bar which is normal, on high idle drops to like 240 bars with strange noise coming from pump, its like cavitation sound but more sharp sound. We did calibration of the pump and control levers, still the same. A took the implement pump out, when i was removing the hoses, i noticed some fine brass shaving. I dissasabled the pump and its absolutely fine no scoring on anything, nothing wrong with the pump. So my question is, what to check next? I also checked pilot pressure and its around 35 bar, little low but not that bad i think. I also removed the brake and pilot piston pump, because i was suspecting it for the brass shaving, only thing i found was some pitting on one of the bearings in the pump, but no sign of from where the brass shaving are. If you have any suggestion plase post. Thank you very much and have a nice day. Also machine have like 20.000 hours.
I forgot, serial number is TWX. I dont know the exact number but that should be enough.
From your description I wouldn’t be looking for a suction line to the pump from the tank that is either sucking in air or restricted somehow. Also check the obvious like hydraulic oil level in tank.
Thanks for tip, we checked supply tube for the pump, its conected with some rubber hoses, some clamps were little loose, so i tighten them, no diference, but tommorow, i will check strainer in the tank. Fluid level was ok.
Hello, little update, all pump torn down, inspected, all seems to be fine. Like i said only pump for brake and pilot have bad bearnig and bronze bearing for swash plate pretty worn, that is why there was little brass shavings in oil, we clean the tank, new oil, all connections on suction side tightened. We did pump control solenoid calibration, pump is maitaining around 20 bars stand by pressure on idle. Speed of implement is now in spec. But i am still trying to sort out problem with low pressure on high idle. On low idle 330 bar with high idle pressure drops. Do you guys have any idea what is going on? One more thing i noticed when holding lever down on high idle there is slightly more pressure then holding lever up. I am starting to suspect the main control, seems to me it is not the pump when is building pressure at low idle. I did check main relieve valve, but seem fine i also tried to fiddle with line relieves, again no change. Thank you for your time