Rough engine vibration on certain rpm

Discussion in 'Freightliner Forum' started by Mike2401, Jan 4, 2025.

  1. Mike2401

    Mike2401 Bobtail Member

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    Jan 4, 2025
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    Hi guys,
    I have a problem that follows me for a while now
    I got a 2017 Cascadia dd15 dt12 900k mi
    At certain rpm, and they are different from gear to gear the engine, or at least it fills like engine, vibrates badly almost like I was driving on a rumble strip on a side of the highway.
    It shows up the most on 9th gear at 1100rpm and 10th gear at 1000 rpm. If I accelerate a bit or lift my foot (+100, -100 rpm) it disappears right away. It is also present on other gears.
    Does not matter of a load weight
    There no vibration when the truck is cold. After a few minutes it starts to appear and fully shows after a few hours of truck working.


    I had that since I bought the truck 500k mi. Usually it appeared after long idle, long empty drive or dpf system issues.
    I thought it was related to dpf filters. Like they ware getting clogged or so. Because after I drove loaded for a while it disappeared.


    But a few weeks ago I got checks on my dash. It wasn't far away from home and driving back I noticed the same kind of vibration.

    Ended up I changed the whole scr box. But the vibration stays all the time for a few weeks now.
    No one knows what is that.

    I afraid it may damage the engine

    I'll be grateful for any suggestions
     
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  3. blairandgretchen

    blairandgretchen Road Train Member

    12,993
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    Dec 9, 2011
    South west Missouri
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    Checked drive line - carrier bearings and driveshaft? Engine mounts?
     
    cke Thanks this.
  4. sbaumann14

    sbaumann14 Road Train Member

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    Sep 1, 2010
    Rhinelander, WI
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    Yep. Bettin it’s driveline related. Ujoints first and then carrier bearing.
     
  5. rix005

    rix005 Bobtail Member

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    Jan 15, 2013
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  6. rix005

    rix005 Bobtail Member

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    Jan 15, 2013
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  7. FLHT

    FLHT Road Train Member

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    Aug 2, 2014
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    u joints ?
    hanger bearing ?s/
     
  8. rix005

    rix005 Bobtail Member

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    Jan 15, 2013
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    The Crank Shaft Damper also known as a Harmonic Balancer has a service life of only 500k and is rarely replaced when fleets cycle these trucks at warranty ending at 500k. The damper eliminates vibrational frequency by a soft rubber compound sealed inside. Over time this rubber hardens and the dampening properties no longer exist. In addition, the action of balance minimizes harmonics created by a rotating crankshaft. The first sign of failure is while standing on steer tire, shaking can be seen or vibration can be felt under feet.
    Door mirrors will vibrate or rattle slightly and, continues until engine rpm is raised to 900 rpm to smooth idle. If this serviceable part is not replaced, the vibration will continue until crank shaft breaks in half usually at number 6. Block damage likely. Also this vibration will transgress though Crankshaft into transmission and early input shaft bearing failure followed by secondary shaft bearing. At this stage there are now multiple vibrations and difficult to pinpoint. Early signs also include rear main engine seal and transmission input shaft seal leaking from bearing wear.
     
  9. Daniel Y

    Daniel Y Bobtail Member

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    Dec 27, 2020
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    If you happen to find the reason. Please let me know too on donnyvice@gmail.com

    i had this issue for the last 3 years and no one could help me find the reason. Not a single dealership or a local repair shop.
     
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