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Diesel engine knocks under heavy load while towing

Discussion in 'Heavy Duty' started by gakimoff, May 18, 2020.

  1. gakimoff

    gakimoff Junior Member

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    Joined:
    Nov 16, 2016
    Location:
    Georgetown, TX
    Ram Year:
    2016
    Engine:
    6.7 Cummins Diesel
    Towed our 5th wheel for 1st time last week with our 2016 RAM 3500 dually we purchased a few months back. I traded in a 2013 RAM 3500 SRW because our new 5th wheel exceeded the towing limits of our prior truck.

    When accelerating from a complete stop or depressing the throttle to maintain speed on a hill, the engine knocks. This sounds similar to how gas engines ping when the fuel detonates instead of burns. The engine only does this under heavy load. My prior truck never did this, even under similar load conditions. It's basically the same Cummins engine. What gives?

    Have any of you experienced this? What was the cause and how did you address it? Thanks.
     
  2. mtnrider

    mtnrider Senior Member

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    Location:
    Georgia
    Ram Year:
    2016
    Engine:
    6.7 Cummins
    My does not make any kind of knocking sound that that? Strange.

    The truck is not tuned and deleted is it?


    .
     
  3. tjfdesmo

    tjfdesmo Senior Member

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    Joined:
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    Location:
    AZ
    Ram Year:
    2019 3500 DRW CTD
    Engine:
    CGI Cummins 6.7 HO
    They are both Cummins, but are they both the same HP and TQ? The DEF allows them to run a bit more timing, which would normally raise NOx emissions, and that will give a bit of timing rattle under some conditions. My 2019 HO does this.
     
  4. Halligan

    Halligan Senior Member

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    Location:
    Massachusetts
    Ram Year:
    2015
    Engine:
    Hemi 6.4
    I'm assuming you bought the 16' used, am I correct? The first thought that comes to mind is a bad injector. Way back when I had a 2004 5.9 Cummins and I ended up with a knocking sound. I dropped it off at the dealer and they diagnosed it as a bad injector. After it was replaced the knock went away.
     
  5. stevenP

    stevenP Senior Member

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    Joined:
    Nov 9, 2014
    Location:
    northern Indiana
    Ram Year:
    2014 3500 DRW
    Engine:
    6.7L Cummins
    Both of my CTD powered HD's... rattle when they are being pushed hard.. and the boost is up. I had a duramax equipped truck before these RAMs, and they didnt seem to have this type of rattle noises. Must be normal as mine, both run fine, and pull like crazy without any complaints.
     
  6. SouthTexan

    SouthTexan Senior Member

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    Ram Year:
    2014
    Engine:
    408 CTD
    Could be multiple things. Injector like someone already stated or even a cracked exhaust manifold which you can check for with a visual inspection. It could also be the DEF injector under high load that you are hearing. My bet would be that the previous owner removed the intake silencer that is in between the turbo and air filter housing. You will definitely hear more engine noise when this is removed. Just remove the hose coming out of the air filter box and if you don't see a big silencer in their with a lot of foam around it, then this is likely your issue.
     

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