2014 6.7 momentary engine knock under acceleration - Dodge Cummins Diesel Forum
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post #1 of 7 (permalink) Old 09-17-2014, 09:19 PM Thread Starter
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2014 6.7 momentary engine knock under acceleration

I tried the search feature but all I come up with is third gen trucks with knocking at idle.
My new truck has developed what I would call an engine knock, sort of like the one you'd hear on a gas engine when the timing is off.
It only happens under acceleration, firs to second and into third gear and rarely third to fourth.
It is a very distinctive, very different sound than the engine normally sounds like. It is louder and with a higher pitch if you will. Happens for about 1-2 secs and then is gone. Again, only under acceleration and as soon as I take my foot off the clutch and hit the go pedal, no noticeable loss of power.

Is this a normal thing for these new engines? I don't want to waist a trip to the dealer if all I am going to get is a "its normal" type of answer.


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post #2 of 7 (permalink) Old 09-17-2014, 10:09 PM
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They all do it, very normal. Doesnt sound right to most!
Gb

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post #3 of 7 (permalink) Old 09-17-2014, 10:14 PM Thread Starter
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Originally Posted by Rigman View Post
They all do it, very normal. Doesnt sound right to most!
Gb
Thanks, I never had that with my old 5.9 so I wanted to make sure

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post #4 of 7 (permalink) Old 10-19-2014, 03:21 PM
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Damnit, this is unfortunate. I am looking to get a 2500 instead of my Tundra because I have a similar knocking coming from mine under accel and when coming to a stop. So far Toyota is replacing the T-case as they feel thats where its coming from....still waiting to get it back to verify.

During my test drive on the 2500 Diesel Ram the other day I was not able to hear any knocking noise. May have to take another drive/extended drive to get more of an opportunity to really hear and feel the truck over a couple days.

Last edited by 14burrito; 10-19-2014 at 03:55 PM.
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post #5 of 7 (permalink) Old 10-19-2014, 03:52 PM Thread Starter
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Its more like an off timing thing, not a hard knock. Trucks fine, just a normal noise.

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post #6 of 7 (permalink) Old 10-19-2014, 08:20 PM
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mine has it too, sounds a lot like timing knock

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post #7 of 7 (permalink) Old 10-19-2014, 11:21 PM
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Originally Posted by smok'em View Post
Its more like an off timing thing, not a hard knock. Trucks fine, just a normal noise.
That's exactly it. When you accelerate hard, the ECM advances the timing to produce more power. If it were a gas engine, you'd call it pre-ignition. On a diesel, its just call "timing rattle". All normal.

You'll find it more prevalent when it is cold out during warm up. They advance the injection timing more during cold warm up to enhance combustion.

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