Komatsu PC300LC Hydraulic Problems

[AKDANDER]

I posted this problem here a while back but am not sure I am using this forum correctly so I will run it by again.
I have a PC300LC-6. I had trouble with the arm cylinder and had it rebuilt. ( the snubber came loose from the piston and beat things up pretty bad. some small pieces went down stream.) The arm still drifts both out and in. Any I ideas what to look at next? I tested the cylinder and believe it is OK. There was some damage to the quick return valve but I cleaned that up and the spool floats freely now. I swapped some suction safety valves around and nothing changed. (Note) When I shut the unit down with the arm full in or full out I can here fluid leaking buy in the main arm control valve area. Any more thoughts out there? Also does any one know where I could pick up some used or surplus parts for the control valve?

 

[mikebramel]

If you didn't clear the debris from the valve, tubing, and hoses before you ran the cylinder you will probably going in circles

 

[02Dmax]

Have you pulled out both relief valves on that circuit and cleaned or replaced them?

 

[simonsrplant]

Reliefs, spools, positive check valve if the cylinder has one... If the cylinder took a dump you will be chasing faults mainly on that system for a long time. Material will be everywhere.
Saw a similar failure on a Hitachi 30tonner... After tearing apart the obvious I dropped the hyd oil to clean the tank... I'd never seen anything like it. Material everywhere. Strainer was plugged, filter caked, it was everywhere. Think that machine was sold not long after that.

 

[Hydraumind]

Check the arm drift prevention valve, it should be mounted on the cylinder itself on the rod side. Maybe this is what simonsrplant called positive check valve
And try to take a look to the compensation valve

 

[AKDANDER]

I did clean the system as best I could. There was a fair amount of junk in the filter but the tank was clean. I did find a chunk of material in one of the compensation valves. I did swap the suction safety valves but did not take them apart. I will give that a try as well as look for the check valve. Thank all of you for the reply's. Does anyone know where I can find some used parts for this unit?

 

[AKDANDER]

Swapped them with some on other circuits with no results. Will try to disassemble them. Thanks. Know where I could find some used or surplus parts for this unit?

 

[02Dmax]

I use Road Builders in Kansas City and have had good luck with used parts from them.

 

[02Dmax]

H&R Construction Parts might be worth a try also.

 

[AKDANDER]

Thanks. I'll give them a try.