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  1. A

    PC55 unload pressure too high

    Thanks Kobe, I was able to get the track back on. So if, I understand correctly, you are suggesting to put a pressure gauge directly on the Pump LS port and plug the LS line coming from the controller (and do vice versa)?
  2. A

    PC55 unload pressure too high

    I didn't check that but I am not sure what that test be indicative off? As an update, I have put a T on the pump LS hose and joined it to the return line on the TS port by putting another T there and a flow control valve just before the T to be able to control how much LS pressure I am leaking...
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    PC55 unload pressure too high

    Hello Kobe, so the pressure drop right to 450 psi on both p1 and p2 when I took LS line off the pump. So it's definitely false load signal. I took the TS line (return line to the tank at the end of the control valve on the work equipment side) and there is no oil draining from that port when...
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    PC55 unload pressure too high

    Thanks for clarifying that Kobe. I've put a pressure gauge directly on the LS line (between control valve & the pump with a T on the pump side) and am reading a 450 psi pressure at idle rpm with no load. I will try taking the LS line off the pump (I need to find a plug for that line) to see if...
  5. A

    PC55 unload pressure too high

    Thanks Kobe. The LS pressure is right at spec around 450 psi. I am not sure how to adjust the minimum pressure. I tried adjusting PC valve on the pump and it didn't make any difference.
  6. A

    PC55 unload pressure too high

    Looking for some help for my pc55. Just changed the pump and control valve due due to some issues. Things seemed to be fine until I put a pressure gauge on the P1 output and the unload pressure is reading around 900 psi which about 450 psi higher than it should be. What should I be looking at as...
  7. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    All this info is very helpful. I'll work on a T setup to be able to test. Really appreciate your help and guidance. Thanks!
  8. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    I've ruled out the easy stuff like the things you've mentioned. I agree with you and I am not willing to replace/repair the pump until I am reasonable sure that it is a pump related problem. It doesn't seem like it because the symptom is quite unique in the sense that all the troubleshooting...
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    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    You are correct, it is a variable displacement pump like yours with a gear pump in the middle for swing and blade. I tested pressure port 1 and 2 with the pressure guage. At idle the pump reads 500 psi which is as per the specified range. Then when the fault occurs the pressure drops to zero...
  10. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    Alright, so the pilot pressure line is not the issue it seems. I tested like you suggested as well as with a pressure guage. Both before and after the fault occurs I have about 550 to 600 psi of pressure. I tested on the boom raise port on the control valve. Hooked up a pressure gauge to it...
  11. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    What do you mean the control for the boom swing is welded? You are talking about the boom offset? Where is it welded? I do have the pressure gauges but it seems I am going to need an adapter (which is showing to be 500 bucks for what seems to be a t-adapter). I think your suggested method would...
  12. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    Yes, originally it has boom swing but its disabled on this machine. I'll have to look into it's ppc valve under the hood. However in the cabin the control for boom swing is welded so it can't be operated. Here is the hydraulic layout of the ppc valves from the shop manual.
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    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    Would this be the right test?
  14. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    What I am struggling to understand is that if its pilot line/pressure related issue how would the swing and the blade continue to operate while I loose boom, arm, bucket and travel. Wouldn't the PPC switch/solenoid related issue kill the entire pilot pressure feed?
  15. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    Thanks! I'll look into the injectors and see if I can replace them.
  16. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    Are you referring to the 2-spool solenoid valve in the picture? If so, I forgot to mention that this was replaced by the dealer.
  17. A

    Need Help with Komatsu PC55 **Possible Hydraulic Issue**

    I have a Komatsu PC55-MR3 that I purchased from China and got it shipped here in Calgary, Canada. The machine was dropped at a Komatsu dealership and they filled up the machine with fluids and diesel and performed the following work: Filled hydraulic fluid, engine oil & coolant Change the...
    • Amjad.kamal
    • Thread
    • hydraulic komatsu mini excavator pc55mr-3
    • Replies: 22
    • Forum: Excavators
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