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Backhoe not starting- Komatsu '99 WB140-2

Discussion in 'Tractor/Loader/Backhoes' started by LoneStarLand, Sep 16, 2022.

  1. LoneStarLand

    LoneStarLand Member

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    Hey guys; did not find solution in the prior recent post
    Komatsu WB140-2N wont turn over- Discussion in 'Tractor/Loader/Backhoes' started by Shblack, Jul 31, 2022.
    so starting fresh with this post...even though the Backhoe will not


    Older & has some worn buttons/switches remaining unidentified
    Had been running and starting consistently; then one day after getting out of the woods, parking in normal location, and cleaning greenbriar and branches from below driveshaft & other; It did not want to start, Checked battery -new as of 12/21 -I noticed the starter was really beat up; so I replaced the starter-
    Battery and @ starter I am getting 12.7-12.8v;
    seems to have good continuity @ all grounds
    checked all (discovered) related fuses; confirmed operable or replaced.
    have tried jumping @ battery, key and direct -screwdriver & jump cables-@ starter to bypass possible breach/loss
    starter has been confirmed operational; flywheel & engine move w socket-not locked up...
    pre ignition shows fuel, power, turn to start then just the tapping starter, or nothing at all
    SO ---- I suspect it must be electrical; no not a genius to figure that out :)
    Discovered some rodent damage @ wires behind console. repaired what I could find; some relays were found- but don't know how to test a relay ?? to determine if it needs replaced.
    Not sure how to test continuity from in the cab to fuse box under hood- maybe extensions on the test leads ?? w aligator clips ??

    This is on a farm/ranch, so just me ever using it; is there a work around wiring to bypass a relay and test that way ?
    20220909_193725.jpg 20220909_193532.jpg 20220905_194115.jpg 20220905_154626.jpg Certainly the most beautiful fuse box; the 'empty' has been replaced 2 a new 80 20220909_193532.jpg This button labeled 'power' but never seemed to do anything previously 20220909_193725.jpg

     
  2. coalrulz

    coalrulz Well-Known Member

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    Good Question
    Location:
    Western US
    Please post machine serial number, electrical schematics can change by serial number. Does the engine turn over with the starter?
     
  3. LoneStarLand

    LoneStarLand Member

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    No sir, not turning over; just tapping of the starter in and out...that is why I think maybe there is a relay or something that should be happening but is not...I'm not the dumbest guy, but I am not mechanic-smart like some folks...sure wish I was...
    Thinking I will check the battery cells just to say I did everything I know...
     

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  4. LoneStarLand

    LoneStarLand Member

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    here is the elec specs if it helps...Still have not discovered the source of the non-start
     

    Attached Files:

  5. Delmer

    Delmer Senior Member

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    So when you turn the key to start, the starter "taps in and out"? That tells me you have power going where it's supposed to but not staying there under load. So you have to do the same checks you're doing under load, which is going to be difficult, so you will probably be bypassing relays, switches etc. to test. No easy way to explain electrical troubleshooting, but I like to start at the battery, then the starter, just like you've done, but now read the voltage when trying to start. A half hour on youtube general vehicle electrical diagnostics, and a power probe should get you pretty far toward finding the issue.
     
    LoneStarLand likes this.
  6. joe--h

    joe--h Senior Member

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    Any chance it's the wrong starter? Teeth are hitting and bouncing back?

    Joe H
     
  7. Coaldust

    Coaldust Senior Member

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    Sounds like a safety relay/starter relay issue. You really need a wiring diagram to help troubleshoot it. Dig into the archives. There are good threads on the subject.
     
  8. franklin2

    franklin2 Well-Known Member

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    You said in your first post that you bypassed everything and hooked the starter directly to the battery with jumper cables? Did the starter work then and turn the engine over? Can you put a picture of the starter up?
     
  9. Dave Neubert

    Dave Neubert Senior Member

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    if you have a battery load tester hook it to the starter and see if you get a power drop. If starter is clicking then the electrical system is doing what it is supposed to sounds like a bad connection that looses power under a load
     
    LoneStarLand likes this.
  10. LoneStarLand

    LoneStarLand Member

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    Have the wire schematics; -posted pdf above
     
  11. LoneStarLand

    LoneStarLand Member

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    Starter works, but engine not turning; starter seems to be popping in and out...enginge & flywheel confirmed as 'not locked up'
    Starter appears to be same size; confirmed it is same #teeth; I have measured the depth to flywheel and starter gears pop out that far (when it is tested freehand) and measured the extension distance
     

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  12. LoneStarLand

    LoneStarLand Member

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    Starter does the same even with straight to starter power...makes me think there is some odd safety relay or ?? that is preventing other functions...may look into trying to test the alternator....not sure how to test relays- yTube perhaps
     
  13. LoneStarLand

    LoneStarLand Member

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    Do not have a Load tester; might test the battery fluids and run it to AutoZone or Napa for a load test
     
  14. LoneStarLand

    LoneStarLand Member

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    Now I still get 12.7 @ my battery and starter; but no power w @ the key & console....
    Could that be rat chewed wire somewhere or perhaps a failed relay ?
    Any advice how to test a relay (or hardwire bypass) ?
    Any good resources to purchase the relays
    Have already tested and replaced all failed fuses
    Fuse3.jpg Fuse2.jpg Fuse1.jpg
     
  15. Delmer

    Delmer Senior Member

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    Spell it out for us. You said the starter works, and now you say the starter doesn't turn the engine over??? That's kind of what a starter should do in my book.

    IF you short the two big terminals on the starter solenoid, what happens?

    If you short the big battery terminal on the starter solenoid to the little terminal on the starter solenoid, what happens?
     
  16. joe--h

    joe--h Senior Member

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    What kind of starter, post a picture of it. If you could record a video with sound it might be helpful.

    I think I've seen this trick eons ago, starter solenoid wasn't moving the bendix far enough & it would just bang back and forth.

    Joe H
     
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  17. Dave Neubert

    Dave Neubert Senior Member

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    Was there a spacer that maybe you left on the old starter
     
  18. LoneStarLand

    LoneStarLand Member

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    Apology for the confusion.; hope this clarifies current experience.
    Perhaps I should have typed The starter is 'operable but not performing intended function';
    when out of the backhoe and tested, bendix pops out and spins. I have measured with calipers the extension and the distance from mount position to the flywheel; these measures are compatible.
    When in the machine it just sounds to pop in and out (tapping) and does not turn the engine/flywheel. Same condition when shorted across pwr to start or ground terminals.
    Lately, I am getting no power at the key/console- though I still have power at the battery, starter, etc.
    I am looking into testing relays; how to test alternator; and tracking down possible breaches in the electrical system.
    upload_2022-9-25_9-47-56.png
    upload_2022-9-25_9-50-21.png
    upload_2022-9-25_9-56-22.png
     
  19. LoneStarLand

    LoneStarLand Member

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    [​IMG]
    A few times early on with the start sequence I was getting a bit of smoke from the battery area...could not see specifically where from the cab...I suspect that is not a good thing :confused:

    [​IMG] upload_2022-9-25_11-44-3.png
     
    Last edited: Sep 25, 2022
  20. joe--h

    joe--h Senior Member

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    When in the machine it just sounds to pop in and out (tapping) and does not turn the engine/flywheel.

    Is this tapping rapid, like machine gun ? How fast, and how long will it do it if you leave power applied?

    Bendix is hitting the flywheel and bouncing back and forth?

    Joe H