Engine knock a 500 miles

MN6.2 · October 30, 2019

21 hours ago, KB Chevy said:

This is my 5th diesel and none have ever sounded like this with the loud knock, and my 2020 does. I can't believe they changed anything from 2019 to 2020 that would cause this obnoxious knocking sound.

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.

KB Chevy · October 30, 2019

That could be a contributing factor, thank you for the info.

KB Chevy · October 30, 2019

1 hour ago, MN6.2 said:

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.

That could be a contributing factor, thank you for the info.

newdude · October 30, 2019

On ‎10‎/‎28‎/‎2019 at 11:34 PM, bass mechanic said:

honestly i dont think for as long as this engine has been around this is a problem sound. diesels are noisy! if it was rod knock it would get louder with RPM and likely get worse under load.

and the fact others have the exact same sound, im sure any dealer will tell me its normal. ill wait till something bad happens and have it covered under warranty.

I watched your youtube upload and the ones you sent. The youtube one I heard it most I think. That deep "da da da da da da da da da da da da" thumping sound I assume is the one? I went to some 2020's we have but they have zero miles on them and didn't have a similar thumping sound. I can definitely hear the DEF injector tick in park that hits about every 1-1.5 seconds.

5 hours ago, MN6.2 said:

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.

No. Same rear flywheel housing on the back 2017-2020.

Edited October 30, 2019 by newdude

KB Chevy · October 30, 2019

1 hour ago, newdude said:

I watched your youtube upload and the ones you sent. The youtube one I heard it most I think. That deep "da da da da da da da da da da da da" thumping sound I assume is the one? I went to some 2020's we have but they have zero miles on them and didn't have a similar thumping sound. I can definitely hear the DEF injector tick in park that hits about every 1-1.5 seconds.

No. Same rear flywheel housing on the back 2017-2020.

Yes it's a deeper thumping sound that is heard. It's harder to get it on an audio file to hear the true sound but it sounds like you can hear it. In person it's very noticeable. Yes i hear the injector tick which you can hear on all diesels and I actually like it. LOL The thumping is obnoxious, I own a RV dealership and my service manager was a Chevrolet service manager for years and worked at the Chevy dealership for over 20 years in different capacities. She stills has connections with the GM reps and has a call into him about it. She's never heard a diesel motor sound like this so not sure what to make of it. The warranty will cover anything that goes wrong but for 77k you would think it wouldn't sound like it does. Also this is my 5 diesel and when i was in the waste business we had 100+ diesel trucks, most large trucks but again I've never heard a diesel sound like this and not have an issue. Thank you for your time, I greatly appreciate your help! Please keep me posted if you should hear any info on this.

Kenny

GPMS · November 9, 2019

On 10/28/2019 at 10:09 PM, bass mechanic said:

heres a video with the sounds

I have the same thing. it sound like shit when you hear it.

CRApex · November 9, 2019

My 2017 had a knock you could hear while slowing to a stop, 2020 does it too. Knock knock sound then goes away once stopped. Had no issues with the 2017

KB Chevy · November 9, 2019

17 hours ago, GPMS said:

I have the same thing. it sound like shit when you hear it.

Yes that's the exact sound. I had a GM rep come and listen to it and he said that's how they sound now but to confirm it he called a GM engineer who did confirm it. Said the motors are quieter in some aspects now and some sounds like the thumping/knocking are more pronounced. I find it very annoying but not much I can do about it.

joelabq · November 10, 2019

Mine has the same noise. Call me weird, but this sound did not bother me at all and i love how this engine sounds as a whole. I think the deeper noises are much less annoying then the higher pitched of the old. It is subjective though.

jhc2 · November 16, 2019

Great video, mine has the same sound. Dealer said it was noise from the egr system and naturally they say it's normal. Hope someone can figure out what it is.

Silverado1 · November 25, 2019

I had a 2018 that sounded like that but my 2020 doesn't I thought that they fixed something on the newer motors

Turtlern56 · December 3, 2019

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.

Anthony Greco · December 4, 2019

On 10/28/2019 at 11:09 PM, bass mechanic said:

heres a video with the sounds

Sounds like a loose harmonic balancer. Have you checked oil pressure with a mechanical gauge? If it’s a bad or loose crankshaft bearing then oil pressure will be lower than normal. Just thoughts of what could be. Hope it’s nothing major.

Edited December 7, 2019 by Anthony Greco
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jhc2 · December 7, 2019

Similar posts on the dieselplace forum so there others with the 2020 duramax with the same problem. Anyone able to post this video to Banks Power? Gale seems to be the utmost expert on the duramax. He tears these engines apart all the time. If anyone can shed a light on the problem it would be him.

Anthony Greco · December 7, 2019

On 12/3/2019 at 5:02 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.

Never stops amazing me what dealers try to pass off as normal. Usually there are one or two Techs on top of these issues. Those are the ones you want working on your truck.