Duramax Engine Rattle-Knock

[Kevin4167]

I purchased my new 2015 Sierra late December and it has about 2500 miles on it (Diesel Option) and while going up through the gears on acceleration if I did not know any better I would think the motor was gasser and it had bad gas because it sounds like spark knock. I have been told (not real versed on this so I might be talking some smack) this is due to the pilot valve which is used to help eliminate turbo lag. I had my 06 Duramax which ran like a scarred rabbit no turbo lag and no knocking. Just wondering if anyone else has had or heard of this issue. Any help would be appreciated.

[2018GMC]

That doesn't sound normal. I would take it to the dealer and have them take a look. You could also drive another duramax and see if it makes the same noise on acceleration. We have a 14 LML duramax in the family and it has been smooth and quiet (for a diesel). Has had no problems whatsoever, currently at 18k miles.

[redwngr]

Duramax injection systems fire multiple pulses per rev at lower rpms. One of the things this does is reduce the amount of 'injection noise' compared to older diesels.

 

Under hard acceleration at higher rpm use of this technique is reduced/suspended and there will be more injection noise.

[Vlad3500]

I have a 2016 3500 dually. I just noticed the noise today on highway. When I cruise at 65mph and slightly press the gas the starts rattling and nocking then it normal...soon as I press gas again it rattles, but on idle does not do that..I'm gonna take it to the dealer let them check it out.

[2TrakR]

Very rare to hear any knock/rattle from my Duramaxs. Could be a few things. Does it do this on different tanks of fuel (could have some bad stuff, maybe try different pump station)?

[jerseydrew]

i heard a rattle from my truck not to long ago and it turns out that there is an oval thing sitting on top of the engine dead center that as the dmax 6.6 logo on it. there is one bolt on that piece that faces forward. mine had come loose. i just snugged that up and my rattle went away.