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Hitachi EX100-2

Discussion in 'Excavators' started by MCF, Jan 19, 2022.

  1. MCF

    MCF Member

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    We just bought a Hitachi EX100-2. When we went and looked at it, ran great, hydraulics were fast, but were unable to actually dig with it. When we got it home and went to dig a hole I was very disappointed. Hydraulics are fast, but it is short on hydraulic power. I checked pressure at the pump and it is 4-4200 psi. I tightened the main relief valve the last 1/2 turn that it had left and no change in pressure. I pulled the relief valve out replaced all o-rings and zero change. I ordered a new relief valve thinking this one is just shot, that will be in next week. Does anyone have any other ideas of what could be wrong? Also does anyone have a parts book for this machine that they would part with?
    Thanks in advance,
    Andy
     
  2. hseII

    hseII Member

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    I can’t say if ours is a -2 or -3, I’ve not got the plate or othe books in front of me.

    Does this machine have the buttons on the display that changes priorities?

    Strong man
    Stick
    Boom

    I know ours performs different when those are adjusted.
     
  3. MCF

    MCF Member

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    It does, and I played with those. Those seem to change speed but do nothing for power
     
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  4. mg2361

    mg2361 Senior Member

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    Was the surge relief valve pressure checked? I think Hitachi calls it an Overload Relief??
     
    Last edited: Jan 20, 2022
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  5. MCF

    MCF Member

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    Where is that one located?
     
  6. mg2361

    mg2361 Senior Member

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    Incorrect term. Surge relief is correct, overload is the circuit relief.

    On the bottom of the control valve. Accessed from below machine. One half of the control valve will have 3 circuit reliefs, the other half will have one relief. The single relief is the surge relief. It is supposed to be set to 5300 - 5350 psi. System relief setting is 5000 - 5150 psi (both set with engine on "P" mode with hydraulic oil at 50*C). So the system has to be set higher temporarily to set the surge relief, then turn system down to it's setting.
     
    Last edited: Jan 21, 2022
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  7. MCF

    MCF Member

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    Today I replaced the main relief valve, with no change. Then I screwed the surge relief in and also didn’t change anything. I cannot get more than 4200 psi on the outlet test port on the pump. All functions make the same pressure. Where do I go next? Angle sensor adjustment?
    Thanks.
     
  8. LACHAU

    LACHAU Senior Member

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    Hi everybody,
    With symptoms like this. The first I will also do as Mr. MG guide.
    Next, I will check the UNLOADING valve set as shown below.
    When this valve set is stuck it will also cause the phenomenon of not being able to increase the main pressure.

    EX120-3 Unloading Valve Detail.jpg
    EX120-3 Unloading Valve.jpg
     
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  9. MCF

    MCF Member

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    what section of the service manual is that in? I’m having trouble finding it. What part usually sticks? Do I need to completely disassemble the valve to get to it or can I just take the plug out on the top and make sure the spool is moving freely with a magnet? Also, Will I have to drain the hydraulic tank again?
     
  10. MCF

    MCF Member

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    Ok, I’m seeing where you are at on the valve now. What you have highlighted in green is what the service manual calls the relief valve, and number 11 on your diagram is called main relief when the service manual calls it the surge relief. So now I’m even more confused. I have had the relief valve which I believe you are calling the unload valve out, torn apart, put together with all new o-rings, now replaced with a new one and have zero change in pressure. With it out I stuck a magnet down in the hole and was able to pull the spool under it up maybe 1/4-3/8” of an inch. Seamed to move up and down freely.
     
    Last edited: Jan 24, 2022
  11. LACHAU

    LACHAU Senior Member

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    Please do not confuse the unload valve with the main relief valve.
    The unloading valve is at the top side and main relief valve is at the bottom side.
    The main relief valve has a screw to adjust, and the unloading valve does not have a screw to adjust.

    EX120-3 Unloading Valve.jpg
     
    Last edited: Jan 24, 2022
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  12. mg2361

    mg2361 Senior Member

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    The system relief controls the unloading valve. The unloading valve is underneath the system relief. They work in conjunction with each other to control system pressure. The system relief actually monitors load sense pressure and when load sense reaches the setting of the main relief (it should really be called a load sense relief) it then allows the unloading valve to shift dumping pump pressure. So what LACHAU is saying is the unloading spool may be sticking and not allowing the system to build full pressure.

    Here at Deere we call the main relief in his drawing a surge relief and the valve over the unloading valve the main relief.
     
    Last edited: Jan 24, 2022
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  13. MCF

    MCF Member

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    So the spool that I can see when I remove the relief valve is the unloading valve correct? That seems to move with a magnet ok. Both the relief valve on top and the surge relief on bottom are adjusted all the way in, and I am only getting 4200 psi.
     
  14. mg2361

    mg2361 Senior Member

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    O-rings on the reliefs OK?
     
  15. MCF

    MCF Member

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    I replaced all of the o rings on the main(top) relief but I did not remove the surge(bottom) relief. I figured I’d have to drain the hyd oil to do that.
     
  16. MCF

    MCF Member

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    Alright, I really need some help guys. I have now adjusted the angle sensor to 4.412v, it was at 4.745 before adjusting. And also swapped solenoids on pump with no change. Could it be the DP sensor? I’m starting to lose sleep over this thing. Haha
     
  17. mg2361

    mg2361 Senior Member

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    Just to rule out something electrical, did you get the blink codes from the PVC (that would be the bottom controller of the two)? Looking into the diagnostic connector with the lock tab up, short the two terminals on the right with a paperclip. Key on and count the blinking codes. They will most likely be two digit numbers for a hydraulic related issue. For example, long flash, pause, long flash, pause three short flashes (23). There could be more than one as well. Post if any.
     
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  18. MCF

    MCF Member

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    There are no blink codes at all, and controller blinks normally without jumper in diagnostic port
     
  19. John C.

    John C. Senior Member

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    I wasn't aware that an EX machine had load sensing?

    Your symptoms sound kind of familiar to a machine I worked on over twenty years ago. Same thing happened, plenty of speed with no load, no power when trying to dig something across all functions. We got tired of all the things it could be and just pulled the pump down. We found the case bore for the swash plate control piston worn out and bleeding control oil to the point of not being able to produce flow at high pressure. Had to replace the pump case to fix the problem. Probably not what you would want to hear but something you should consider.
     
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  20. MCF

    MCF Member

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    Pump was gone through by a reputable shop the same time as the engine was overhauled about 300 hrs ago. So I would think that isn’t the issue. You can hear the oil bypassing in the valve bank when you bottom out any function I’ve had both reliefs out and re-sealed now, also tried a new relief on the top with no change.