12.7 detroit studders and knocks

Discussion in 'Freightliner Forum' started by ptwn1, Jan 22, 2014.

  1. Kari77

    Kari77 Bobtail Member

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    I have a series 60 that has a loud knock. Seems to be injector issue. Installed new injector on hole #1 still knocking. Unplugged injector harness at hole #1 and knock goes away. Why???!!!
     
  2. Chubby Fly

    Chubby Fly Medium Load Member

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    Did you do the work? Thats an important piece of infor to make sure it was done right with injector height and etc.
     
  3. Kari77

    Kari77 Bobtail Member

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    Have a knock on hole #1 changed injector and still knocks. When I unplugged the injector harness from hole #1 the knock goes away. Compression test passed. Checked oil pan and lower engine for anything funny.
     
  4. Kari77

    Kari77 Bobtail Member

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    Nope. Came in on the back end of this one. Set injector height and valve lash myself when I got to it. Didnt do the swap of injectors. Checked with mechanic previously over the job to make sure no orings were cut.
     
  5. Chubby Fly

    Chubby Fly Medium Load Member

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    sounds like possible o-ring issue from the install then
     
  6. Rideandrepair

    Rideandrepair Road Train Member

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    What about injector cup damage? Any idea how it looked. If damaged, did you install a graphite crush ring, along with a the big fat O ring, to seal it up?
     
  7. Kari77

    Kari77 Bobtail Member

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    The orings look good. And after all injectors were install a compression test was performed. Held steady for over 3min.
     
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  8. stranger

    stranger Road Train Member

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    If you have a scanner, see what the engine coolant temperature sensor is showing. I had one that had a horrible knock that was there 95% of the time when warm. Every now and them it would straighten out and sound great. Coolant sensor was sending to the ECM the engine temp was 75 deg, throwing the injector timing way off.

    I put in all new injectors, two at a time, chasing it.
     
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  9. jotz007

    jotz007 Bobtail Member

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    Are u suppose to install graphite crush ring along with fat auxiliary ring on a N2 injector 12.7 ddev 4?
     
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  10. Rideandrepair

    Rideandrepair Road Train Member

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    Yes,
     
  11. jotz007

    jotz007 Bobtail Member

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    How about injector calibration if i installed new sets?
     
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