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Engine knock a 500 miles

bass mechanic
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bass mechanic Enthusiast

bass mechanic

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that was published in 2017, so its not relevant to our engines. if the 2017 engines knocked so would ours. has to be something that changed on the new L5P

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bass mechanic
bass mechanic

heres a video with the sounds  

Sask Farmboy
Sask Farmboy

My first chime in for this topic. My 2020 Denali DRW is being built in 2 weeks so I will be checking it out closely. I used to be a Chevy tech and finding stuff like this was my life. I

MN6.2
MN6.2

Didn't they have to change the back of the engine to accommodate the new 10 speed transmission? Doesn't seem like enough to create a knock like that but that is one major thing they changed. 

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Cool J Enthusiast

Cool J

Posted
Posted

I would assume Banks has done a great amount of testing on the 2020 Duramax and wonder if they have heard the same sound that we all are hearing.

Tomato Enthusiast

Tomato

Posted
Posted

Key takeaway is that it sure seems to be coming from the EGR system. 

redwngr Senior Enthusiast

redwngr

Posted
Posted (edited)
22 hours ago, bass mechanic said:

that was published in 2017, so its not relevant to our engines. if the 2017 engines knocked so would ours. has to be something that changed on the new L5P

Which might mean the thump is something related to the 10 speed or the new fan and accessory drive.

 

(what's changed, lets look there first)

Edited by redwngr
Capt.Wackencracker Enthusiast

Capt.Wackencracker

Posted
Posted

Broke out the stethoscope and it seems loudest at the egr on the passenger side 

Gonna put a few hundred miles on it then go to the dealer with my stethoscope and see who needs a hearing test.

It's also starting to high idle a lot.

jhc2 New Member

jhc2

Posted
Posted

Have been following problem also.  First dealer said it was a "normal" egr system sound.  Next dealer said it was also "normal".  This is my 4th dmax and none of the others had this knock.  I agree with Cool J that 

Banks takes these engines apart all the time.  I was wondering if there was a way to send Banks the sound clip from Bass Mechanic since they could probably figure it out.

Capt.Wackencracker Enthusiast

Capt.Wackencracker

Posted
Posted

That sounds like a great idea. 

Unfortunately, that's beyond my computer literacy. 

I think if this was posted on YouTube,  it would get a lot of hits.

Then maybe gm would have to pay more attention to our problem. And we would probably get more response from other owners with the same problem who can help join the cause.

I looked pretty hard on YouTube and the best I could find was a lot of ticking complaints for duramax. 

A good video might get Gale Banks attention. 

Tomato Enthusiast

Tomato

Posted
Posted

I sent an email to Banks asking if they have observed this.  In addition, I asked if they had a programming solution of any kind.

 

Sonny James Enthusiast

Sonny James

Posted
Posted

I am wondering if the folks that have commented on this post can add another post stating their make, model, and trim.  The reason I say this is becuase I wonder if the noise is more noticeable on certain makes such as a Chevrolet 3500 LT, or LTZ or GMC SL or SLT than say a Chevrolet High Country or GMC Denali or 2500HDs.

 

I currently have a 2020 3500HD Denali that definitely makes the noise.  The noise became louder around 500 miles.  But other than when I first start it, I don't hear the noise once I start driving.

 

I do however have another noise that is prevalent at 1550 RPM.  The dealer is getting ready to swap with me for another 3500HD Denali ( last 6 of VIN 30 numbers lower than my current truck) that doesn't make the noise.  I will report back on the other Denali truck as to whether there is a loud clunking noise coming from inside the cab.

dwoods123 Enthusiast

dwoods123

Posted
Posted
27 minutes ago, Sonny James said:

I am wondering if the folks that have commented on this post can add another post stating their make, model, and trim.  The reason I say this is becuase I wonder if the noise is more noticeable on certain makes such as a Chevrolet 3500 LT, or LTZ or GMC SL or SLT than say a Chevrolet High Country or GMC Denali or 2500HDs.

 

I currently have a 2020 3500HD Denali that definitely makes the noise.  The noise became louder around 500 miles.  But other than when I first start it, I don't hear the noise once I start driving.

 

I do however have another noise that is prevalent at 1550 RPM.  The dealer is getting ready to swap with me for another 3500HD Denali ( last 6 of VIN 30 numbers lower than my current truck) that doesn't make the noise.  I will report back on the other Denali truck as to whether there is a loud clunking noise coming from inside the cab.

Ours is a 2020 GMC 2500HD SLE Duramax that we custom ordered.    It was the first SLE in the dealership in December and the noise has been there from day one  at 7 miles on the truck.  

tonysnoo New Member

tonysnoo

Posted
Posted

I just picked up a 2020 Denali HD2500 from a dealer in another state late last week. I have the "thump" just as it sounds in the vids. It was not noisy when I picked it up but it certainly was noticable when I first fueled. It now has 800 miles on the truck and it's very noticable. It does blend away at rpm. It is not a clicking ticking or even a sharp sound like an exhaust leak.

 

The compressor "thump" is the best description for sound I hear. The frequency is about 4-5 beats a second kinda like the firing tempo of only one of the cylinders. 

 

I'm all ears as to what anyone finds. 

dwoods123 Enthusiast

dwoods123

Posted
Posted

This was on another forum....   As promised here is an update on my previous post regarding the thumping/knocking noise many are experiencing with the 2020 GM Duramax. After having my new truck in the shop for two weeks and the Dealership tearing down the top end of the engine to complete adjustments to the valves, the Dealership advised that the problem was related to the clutch in the fan. I was surprised with this as one of the first things they did when they first started to diagnose the problem was run the truck with the drive belt removed which they did with no change in the knocking noise. So I have the truck back and have been told that they are now waiting for a plan for repairing the problem from GM. I will update this tread as soon as I hear what the plan is.

FLTRXS Enthusiast

FLTRXS

Posted
Posted

I just sent a video from inside my cab to my Dealer for him and the service MGR to listen to.  2020 GMC Denalli 2500HD, 2700 miles and its very loud now.  They are going to send on to GM and see if they have any answers.

 

Hope its something they can correct, its pretty bad to have a brand new 75K truck that sounds like its falling apart.

Clint GEFFERS New Member

Clint GEFFERS

Posted
Posted
On 12/3/2019 at 4:02 PM, Turtlern56 said:

I have a 2020 AT4 HD 400 miles now and mine has made that exact same knock as the video outlines.  I commented to the salesman about it but he said he wasn’t that familiar with any of the sounds.  I had been waiting a month for delivery bc of the GM strike.  I went back to the dealer the same day I took delivery last week and made them start another diesel and it had same knock but not near as loud as mine. Heard three others since with no noise. It’s Horrible at idle and seems to go away about 900-1000 rpms.  Some mornings not audible for a minute or two then comes on strong as it warms. Service manager today says it’s normal and they printed me off the ticking service bulletin. It’s a knock not a tick. He also told me to drive it and about halfway through oil life if still audible then they might investigate it. It’s a little embarrassing I’ve had a couple people ask me “what’s that knocking?”  I give them the $70k shrug and say it’s normal. Lol. I hope they figure something out. Reprogram an injector if it’s like a fuel knock or something.  Found this thread researching and thought I would chime in. 

I have the same issue gets louder when engine reaches operating temperature. Dealership gave me the ticking printout like everybody else. I had the dealership send videos of it to GM and after a week went buy they said it is normal. Then they gave me a printout. It is not a ticking sound. Frustrated!!!

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