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Hitachi EX100-3 problem with relief valve

Discussion in 'Excavators' started by JDirt, Mar 2, 2018.

  1. JDirt

    JDirt Well-Known Member

    Joined:
    Jun 16, 2017
    Messages:
    72
    Location:
    Competition, MO
    I have an excavator that is giving me fits, maybe someone can help me out.

    I have rebuilt the main control valve and the electric solenoid valve block. Put it back in, and I seem to have flow, but my pressure won't come up. All actuators work with a light load, but it doesn't have any hydraulic power. Won't lift itself up, won't dig much, won't track up a hill. Before the rebuild, the machine would lift itself up, dig, etc.

    So I put a gauge on the main pump. Every function to relief is 2600-3000 psi. Book says 5000-5250.

    So I try adjusting the main relief valve, I had it out when I rebuilt the valve stack, so I thought it might be out of adjustment. I've turned it both directions several turns, no change. At about 5 turns in, it got tight, like it bottomed out, still no change. I turned the overload relief for the bucket down a few turns and relief for that function dropped below the rest.

    I don't think it's electrical, because I can unplug the swash control solenoids and put the pump full bore, and I still never see more than 3000 psi from the pump. The only difference is with the solenoids plugged in normally, the machine just seems to go to relief @ 3000 on the gauge. When they are unplugged, same reading, but kills the engine. Am I right in saying this eliminates any electrical problem?

    I have checked for trouble codes, and get 35, which is arm bottom pressure sensor fault. The troubleshooting manual says the symptoms of this is poor combined operation. That doesn't sound related, and I think I've had that code since I've had the machine, without ill effects.

    I have put in a new dp sensor, adjusted it and the angle sensor to specs. I've also replaced the wiring to the right rear of the machine.

    So, does this sound like the relief valve took a dump? It's $550 from Deere, unless someone knows another place to get one. Or is there another possibility?
     
  2. MCF

    MCF Member

    Joined:
    Dec 28, 2021
    Messages:
    15
    Location:
    Blue Mounds, Wi
    Did you figure out your machine? I’m having the same issue with mine. With the main relief screwed all the way in I’m only getting about 4,000 psi. All of my electronics are working, hydraulics are fast, but no has no power.
     
  3. 955cat

    955cat Member

    Joined:
    Nov 25, 2021
    Messages:
    22
    Location:
    North Carolina
    I just bought a angle sensor for a120-2 hitachi online for around $50 middle of the road they were $35 to $120 Deere wanted $650 plus have you looked online. Mine works fine don’t know how long it will last , but I’ve run about 20 hrs.
     
  4. JDirt

    JDirt Well-Known Member

    Joined:
    Jun 16, 2017
    Messages:
    72
    Location:
    Competition, MO
    Put in new relief valve, dp sensor, angle sensor, 2 control solenoids, pump controller. Still acted the same, my solution was to trade it off for a newer machine. I'm back to work now.
     
    John Shipp likes this.