I am new here and this is my first post and excavator. Also I will likely get some of the terminology wrong. Please bear with me. I recently purchased this machine and have been working through many hydraulic leaks, leaks appear to be corrected at this time. I have things operating but not like they should. The stick is the only pilot controlled operation that will always work. The tracks, blade, and aux controls are directly tied to there respective spool valves. Every function that is directly tied to a spool valve operates as it should. If I feather any of the directly controlled spool valves all pilot controls will work as they should. All I have to do is touch a manual spool and the pilot controls will work even after I release the manual spool, once I stop using the pilot controls then I need to touch a manual spool control to get the pilot controls to operate again. One other thing if I move the pilot control for the stick then the other pilot controls work as the should. First thing in the morning all controls work as they should when the unit is cold, after 15 minutes or so it will stop responding, this is at idle. If I operate any manual spool at idle then the pilot operated controls will function. With the throttle up over 50% sometimes things work as they should but with a little lag in the response. Once one pilot operated control is working the other pilot controls will work also, it is when you stop using them that they stop responding. I have verified the pilot and main pump pressures. These are where they should be. All fluids and filters have been replaced I have replaced the seals on all hydraulic rams as they were all leaking. The valve that is attached to the slew motor was cracked and has been replaced. Their is a pilot pressure accumulator on the pilot circuit could this have any effect to the operation? Thank you for your time and any help.
Sounds like the accumulator or a check valve, leaking off pressure in a short amount of time. Do yo have the manuals and is there any check valves on the pilot valve bank. I am confused on the manual spool operation you are talking about, unless your talking about manually moving the spool valve?
HarleyHappy, Thank you for the reply. The blade, left and right track and auxiliary hydraulic connection are all manual control. They are connected to their spool valves with a cable or lever. Hope this helps clear up any confusion. I will look at the manual for any check valves. Thank you
Sorry for the delay in responding it has been a busy week. Looking over the hydraulic diagram their is a check valve between the pilot circuit pressure regulator and the pilot pressure accumulator. I wont be able to tear into it till this weekend. Is there a recommended way to test the pilot pressure accumulator. It is quite small and looks to be made of cast iron. It is not leaking but I believe that their should be a bladder of some kind inside the accumulator correct? I likely have the fittings to go between the accumulator and the system and can verify the pressure to the accumulator. If I shut down the engine the accumulator should retain some pressure correct? Provided that the check valve is operating. Thank you for your time again
The accumulator will hold a nitrogen charge pressure, in that bladder. That bladder acts much like a bladder in a potable water pressure tank. It makes sure you have smooth pilot operating pressures by absorbing spikes and dips in pressure. You need special tooling to check pressures and for filling. These are reasonably cheap on Amazon. It’s not like checking tire pressures. Just checking pressure with a non contained gauge, you could lose half your pressure. They usually come pre-filled but any shop that uses nitrogen can usually fill them, for a fee.