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Komatsu excavator no hydraulics

Discussion in 'Excavators' started by Bertrrr, Jun 9, 2020.

  1. Bertrrr

    Bertrrr Well-Known Member

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    Occupation:
    mechanic
    Location:
    South Louisiana
    Got this machine working pretty good , been sitting for a few days , had to charge the batteries to get it started but all sounded good, cannot get any of the hydraulics to respond even with the safety latch pushed all the way down,
    Will look at that micro switch tomorrow to see if that is the culprit , had to add about 4 gallons of hyd oil to the reservoir and thought that was the problem,
    Am I missing something ? this is an OLD machine with numerous wires cut, bypassed etc. but it was running fine when I parked it and shut it down a few days ago.
    thanks for any info you guys may have,
     
  2. John C.

    John C. Senior Member

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    A model and serial number would be a good way to start working on your problem.
     
  3. uffex

    uffex Senior Member

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    Good day
    May be worth checking the control lock out.
    Kind regards
    Uffex
     

    Attached Files:

  4. Bertrrr

    Bertrrr Well-Known Member

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    Thanks for the file, it's a good start,
    this machine is a PC-128-UU and has been abused for years so lots of wires or either disconnected or tied together or missing altogether , mechanically sound just all the little issues keep popping up , thanks again
     
  5. Bertrrr

    Bertrrr Well-Known Member

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    Well I've tried everything I can think of with this beast,
    This thing ran really good until I parked it for the weekend, got here Monday and went to start it , Batteries DEAD, not a smidge of power, hooked up charger and got it to kick off, No action on the hydraulics ,,,,,,NADA,,,, it was working fine until I stopped it for the weekend. swapped out a weak battery, tested the Control lockout - switch works - blead air from hydraulic pump ,filled with oil since it was out of the glass, pretty much exhausted all my ideas on chasing this down, does anyone know how I can bypass the control lockout? it seems to be the only way ALL the Hydraulics would be deactivated at once.
    thanks for any info you guys might be able to share,
    :(
     
  6. John C.

    John C. Senior Member

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    I don't recall those machines having an electrical lock out. As I recall it was just a simple valve under the cab that moved manually when you put the left side console down or just a lever to the valve. If is is electrical you are going to need a book with a wiring diagram.

    On the dead batteries, do you know if the battery disconnect shifted to off when you turn the key off. A lot of those old dogs had shut off cables installed on the fuel pump because someone couldn't figure out the electrical stuff on the shut down system. People would forget to turn off the key or would turn off the key and the disconnect didn't drop out.
     
    uffex likes this.
  7. heymccall

    heymccall Senior Member

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    Can you loosen a pump output line and then momentarily run the engine?
    Just wondering if the drive coupling failed, meaning the engine no longer drives the pumps.
     
    mikebramel and DB2 like this.
  8. mikebramel

    mikebramel Senior Member

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    Thats a good thought. Other option maybe key was left on.... is the lockout coil burnt out and open winding
     
  9. uffex

    uffex Senior Member

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    Good day
    John is a very good source of Komatsu information if your pilot system is as he suggests a simple hydraulic valve you could by-pass this linking input to output, it would be real helpful if you have a hydraulic schematic for your machine it sounds as if a manual may be a good investment, for a few dollars you should have a much needed wiring diagram.
    Kind regards
    Uffex
     
  10. Bertrrr

    Bertrrr Well-Known Member

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    Thanks for the info and input, I have considered a bad coupling and have not ruled it out but it's a last resort check as pulling the pump off would be extremely hard , probably have to pull the engine from the machine or remove the counter weight off of it, the control switch in the cab opens and closes the grounding circuit to some relay or solenoid that allows the hydraulic action to happen. As to the battery issue the only thing that had power going to it was a Volt meter I installed , I doubt it would drain the battery but I'll re wire it to be alive when the key is on from this point forward. I did find a cut wire under the cab area late yesterday and will chase it down today and see if that corrects things, I will post when I have more into, I did buy a service manual and use it for reference quite a bit, it just doesn't cover everything you run into. Thanks again for all your helpful hints.
     
  11. Bertrrr

    Bertrrr Well-Known Member

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    Occupation:
    mechanic
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    Found a loose wire under the machine this morning, applied 24 volts and all the hydraulics came alive again,
    Thanks for all you guys help.
    Still got work to do on this dude but making progress now , no doubt I'll need more input from you guys at some point , thanks again for all your input,
     
    JPV likes this.