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Komatsu PC80MR-3 – hydraulic load sensing problem

illy ยท 2025-02-01 03:44

Hello, I'm troubleshooting a hydraulic load sensing problem on this excavator. When cold machine works fine - the load sensing pressure is following the main pump pressure. Doing what ever the load sensing does - raising, lowering, adjusting the pump flow. But then... When the machine heats up, in one moment, load sensing pressure gets stuck between 90-100 bar (1305-1450 PSI). That puts a lot of load on the engine, RPM almost to idle. All commands work but the movements are rough. Any idea where to start looking? P.S. There is a electric solenoid valve on the pump regulator. How much is he involved in load sending pressure adjustment?

Replies7
  1. #1illy2025-02-03 15:51

    The solenoid I mentioned is called Tvc valve but the manual got nothing about electrical system. Is there any information about the working principle? And, is it possible to enter some kind of diagnostic mode via monitor?

  2. #2Simon C2025-02-03 19:10

    Wondering if that solenoid could be dropping out once it gets to a certain hydraulic oil temperature. Could hook up a meter to the Solenoid while running and watching the meter. If it suddenly changes voltage, would be worth looking into. I worked on the electrical of Dash 5 and 6 machines, but not yours. Simon C

  3. #3illy2025-02-10 03:45

    This solenoid regulates the pump max. output (via the eco-power button on the display in the cab). I've disconnect it and machine worked completely normal until the fault reappeared. So this solenoid doesn't create this problem.

  4. #4illy2025-03-12 04:35

    Now I'm working on a Komatsu PW118MR-8 and it has the same problem! When in low idle and commands in neutral LS is 90 bar (1305 PSI) and the pump is on 180 (2610)! It seems that there is a factory issue. Anybody knows something about this? Is there any bulletins regarding this issue from Komatsu?

  5. #5illy2025-03-12 05:35

    @John C. Hello sir, I've seen you around a lot of threads with Komatsu machines. What do you think of this?

  6. #6Simon C2025-03-12 10:40

    Have not seen John C around the site lately. Maybe I have missed him. He has worked alot around Komatsu machines. Hope he is okay and can assist you. Think Lachau is the other member that is good on Komatsu stuff. Simon C

  7. #7illy2025-03-14 04:20

    @LACHAU Hello sir, I've seen you around a lot of threads with Komatsu machines. What do you think of this?