12.7 bull gear

Discussion in 'Trucks [ Eighteen Wheelers ]' started by catwrench55, Mar 26, 2015.

  1. catwrench55

    catwrench55 Light Load Member

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    Well changed my oil for the first time since buying my 98 Pete with a 12.7, 745000 miles. Found metal shavings on plug, after removing accessory drive found the rear half of the teeth on the bull gear are the source. However I was surprised that I could barely see any play in the bearing to be wearing the teeth. My biggest question is can I get by a while to make a couple pay checks or no?
    Thanks
     

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  3. mhyn

    mhyn Road Train Member

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    no, stop it. fix it !
     
  4. Smellfunny

    Smellfunny Road Train Member

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    Agreed fix it. Need to look at all the gears after you get front cover off. There are one or more in there that look like that or worse.
     
    Iguana and mhyn Thank this.
  5. sailboatjim

    sailboatjim Light Load Member

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    It looks like something as fallen into the gear and cause that damage.
    From the pic it doesn't look like wear damage to me.
    I seen this many time in my life on high dollar printing presses with have huge bull gears that run around a CI drum. Operators would leave bolts loose or lying around and the would get in between the print cylinder and the press and cause damage.
    The only way to fix it is with a stone or even a file but unless you can get to the other gears it may not help.
    If it can be determined that something got into the gears and you can find and repair that, truck was running perfect with little blow by, I would probably attempt to file them.
    If you can use a stone then use a stone to do. All you are trying to do is remove the rough spots.

    I had something similar to this happen on a N14 once.
    The truck would crank but would not stay running.
    Pulled the crank sensor and found a piece of gear on that sensor (magnet)
    Took the debris off and ran it. Never had a problem and have no idea were the metal cam from to this day.
     
  6. catwrench55

    catwrench55 Light Load Member

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    Truck runs starts and sounds fine. Was overhauled about 20000 miles ago so definitely a possibility of something foreign causing that. No broken gears just roughed up. The accessory drive and cam gears look great. Guess I'll just have to tear it down and see. Does the idler gear usually need replaced at the same time? Does it run on a bearing?
     
  7. tommymonza

    tommymonza Road Train Member

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    I was thinking the same thing that it does not look like wear.

    I bet there is another gear in there with missing teeth and that is what you are seeing in the pan and in the teeth of the bullgear.
     
  8. mhyn

    mhyn Road Train Member

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    the teeth of idler gear or camshaft's gear..
     
  9. Frghter Century 12.7 Detr

    Frghter Century 12.7 Detr Light Load Member

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    I have a 12.7 also and 815,000 miles and I agree with the other comments. Looks like a piece of metal fell through those gears.
     
  10. catwrench55

    catwrench55 Light Load Member

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    Just to update the thread, found no real slack in the bull gear bearings when disassembled. Still not sure as to what or how caused the damage to the gear but I also replaced the idler gear behind it as it had one broken tooth. Either way hopefully I am good to roll for a while.
     
  11. Smellfunny

    Smellfunny Road Train Member

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    The tooth that broke off may have wedged in between another gear. Look at everything very close. The piece may have fallen out or still be there. Look at every tooth and in between them of every gear that rides in the position that you have damage.
     
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