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D31PX-21 Komatsu Dozer travel and work equipment stops abruptly

Discussion in 'Dozers' started by Noland, Apr 23, 2020.

  1. Noland

    Noland Member

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    Hi there! I hope everyone is doing well and staying safe!

    I have a 2001 Komatsu D31PX-21 bulldozer. Does anyone have any suggestions on what would cause the machine to abruptly stop meaning the machine came to a sudden stop while backing up. The engine cranks and runs fine and the gears will shift but nothing works. The machine won’t move forward nor will it reverse. The work equipment (blade lever) also stoped suddenly at the time and the travel. Both lock-out levers are in the up position and still nothing works. I’ve checked hydraulic oil level and it’s full and I’ve also checked for blown fuses and none are blown. Sounds like it’s something simple like a bad safety switch, solenoid etc but don’t know where to start looking.

    Any help will be greatly appreciated!

    Noland
     
  2. southernman13

    southernman13 Senior Member

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    I’d look at the lock out switches/wiring on the levers. Sounds like one may have failed. Could be one slid down and not making contact all the way or a wire broke. Wouldn’t think it shorted out due to no blown fuse. I’d bet it’s something simple like that. Good luck.
     
  3. Noland

    Noland Member

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    That’s kind of what I’m thinking also. I haven’t started working on it yet but that’s where I’ll start. Both lock outs work independently. I’m not sure how the two connect together or even if they do. The machine will crank but neither levers move anything. They both stopped functioning at the same time. I’m like you I think it’s something simple it’s just a matter of chasing it down.
     
  4. southernman13

    southernman13 Senior Member

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    the left lever locks out the travel. I know it does on my two Komatsu dozers. I have an older D31px-21 and it has a micro switch on each lever that’s activated when u move the lever. Good luck
     
  5. jvd

    jvd New Member

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    did you find out what it was i have the same dozer and ii turn machine off and when cranked back up i had no hydrolics on blade or travel checked switchs i get a code kb130
     
  6. Noland

    Noland Member

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    Still working on it. What year model is your machine? This one is a 2001. It doesn’t have a screen to display error codes so unless there’s somewhere to connect a code reader I’m not sure it has codes.

    At first we thought it was a bad park brake solenoid. When the Lock-out (safety) level is pushed down it activates the PB solenoid and allows hydraulic fluid to flow to the other pilot controls. We replaced the solenoid but that didn’t fix the problem. My Mechcanic now thinks it might be the pilot pump not producing enough pressure to open/close the spools. Next step is to check the psi on the pilot pump but haven’t done it yet.
     
  7. Noland

    Noland Member

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    Update: I wanted to give an update on the what we figured out the problem was. After spending $800 on a 4hr service call from the Komatsu dealership their techincian said the problem is the main HST pump went out. The pump was producing some hydraulic pressure but not enough for the attachments to function and thats why it shut down all of a sudden. They quoted me a new pump at $23,000 plus tax. A quick recap of recent repairs: Two years ago I replaced a final drive that cost $12,000 just for the drive plus. Less than a year of the HST pump I replaced the entire undercarriage at $5,500 just for the parts. So since the machine was only worth maybe $25,000 (at best) in good condition I decided to sell it for salvage.
     
  8. southernman13

    southernman13 Senior Member

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    Wow wish i would’ve know I would’ve bought it for the undercarriage if it would fit mine. I have a D31p-20. I need the track frames. Who bought it. Maybe they’d be interested in selling parts idk. Sorry for your aggravation I understand
     
  9. Noland

    Noland Member

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    The guys name is Kent Baugh Equipment and Parts. He’s out of Texas. His contact info is in the attached pictures.
     

    Attached Files:

  10. southernman13

    southernman13 Senior Member

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    Thanks man!
     
  11. epirbalex

    epirbalex Senior Member

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    I might have the wrong pump but I would say your quote is far to high for the pump
    https://www.google.com/search?q=D31...Y7XMBHcrkA0IQ9QF6BAgKEAE#imgrc=OHq7TPVLK9RcqM
    https://en.av-gk.ru/catalog/komatsu/d31px-2r/180040/
    The second link has the pump priced little over 400 dollars if its the right pump . I searched for a D31 px-21 pump on google after the Komatsu parts list showed what I thought was a very cheap pump to see if the pictures matched , much the same by the looks .