Eaton fuller 10 speed light roar and slight loss of power

Discussion in 'Ask An Owner Operator' started by Jihye, Feb 21, 2020.

  1. Jihye

    Jihye Bobtail Member

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    May 30, 2019
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    I have a 2012 freightliner coronado with a dd15 motor. Ive noticed in the low gears 1-5, the truck has enormous power. It will really get up and go, but in the high gears 6-10, upon switching gears I hear a light roaring noise or like something is spinning and the power (speed) of the truck lags a bit. If I gradually (slowly) press the accelerator it doesn't make that noise and everything is smooth. It makes going on to the highway from the entrance ramp a real hassle. Please help me!!
     
  2. Hulld

    Hulld Road Train Member

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    When you experience the problem is the tachometer rpm climbing but the speed is lagging?
    If so it could be a slipping clutch.
    If the tachometer and speedometer are proportionate to each other it could be a blown boot on the charge air system.
    Do you have a boost gauge?
     
  3. Jihye

    Jihye Bobtail Member

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    May 30, 2019
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    Yes... thats exactly whats happening. The Mechanic said he recalibrated the clutch. The truck only has 340k on it. Im not to sure if it has a boost gauge but I will check tomorrow.
     
    Hulld Thanks this.
  4. Hulld

    Hulld Road Train Member

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    If the RPM is rising and is not proportional to speed rise then you definitely have a slipping clutch.
    Is there any free play in the clutch pedal before it starts to engage?
     
  5. Jihye

    Jihye Bobtail Member

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    May 30, 2019
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    Yes I have the 2 inch free play in the clutch pedal
     
    Hulld Thanks this.
  6. Hulld

    Hulld Road Train Member

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    If you have the required free play and the clutch is still slipping in the higher gears ( the higher the gear the more load is applied to the clutch) then you have clutch replacement as your only option.
     
  7. stillwurkin

    stillwurkin Road Train Member

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    If the clutch is slipping, you should smell it ( like a hot brake smell) also any i have had slip, you will soon loose your free travel in the pedal.
     
    Hulld Thanks this.
  8. Hulld

    Hulld Road Train Member

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    Upstate NY
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    If you stay in it long enough you may get a smell but any of the ones I have had slip on me I would back out of it and let it catch again.
    Also most of the big trucks use ceramic friction material and they don’t really smell a whole lot when slipped.
    With that being said the old organic friction material had a horrific smell when they slipped.
    Also If you have the friction material glazed they will slip but still have free place.
    My last one I could slip it at will in high gear if I choose to and it still had free play.
    I ran it that way for three months before I got to where I had the available time so I
    could change it
     
    Last edited: Feb 22, 2020
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