Engine knock a 500 miles

bsmall1564 · April 20, 2020

I just turned 600 miles on my GMC Sierra and started hearing that dreaded knocking sound. I can't believe this is a normal sound. Never heard anything like it on my 2008. Guess I'll have to wait and see, hopefully it won't get any louder.....

bass mechanic · April 20, 2020

I just turned 600 miles on my GMC Sierra and started hearing that dreaded knocking sound. I can't believe this is a normal sound. Never heard anything like it on my 2008. Guess I'll have to wait and see, hopefully it won't get any louder.....

I’m at 5k miles still 36% to go before my oil change and I would say it’s definitely not as loud as when it started

Sent from my iPhone using Tapatalk

Schmudder · May 11, 2020

2020 Sierra AT4 3500, same knocking sound, started around 500 mi (was quiet when I took delivery). Is about the same volume as the OP's truck. Dealer claimed that removing the accessory belt significantly reduced the noise but due to "insurance reasons" could not demonstrate with me at the bay.

Sierra Knock.m4a

Edited May 11, 2020 by Schmudder
Added recording

Jrscrib · June 29, 2020

I have been working on these since they came out 19 years ago and each time they do something to make them quitter you hear something else. Well I have also owned a 13, 15, 18 and now a 20 I know for a fact my 18 made the same noise the bulletin states as a tick but I would agree it is more of a thump and this is more noticeable in my 20. The noise changes as the oil breaks down and usually the noise is gone before I change it. I can’t say for sure what the noise is exactly from but I can say without a doubt it is normal.

The real question is has anybody had or heard of a duramax with this noise fail?

bass mechanic · July 13, 2020

I had my oil changed for the first time about a month ago and I now have about 8,000 miles on the truck. It’s been a while since I heard it but I think the noise might be gone or at least it’s a lot less than it was.

Sent from my iPhone using Tapatalk

Edthechevyman · July 16, 2020

I just bought a 2019 model with 6k miles on it. Mine sounds horrible. Back in the day, we would have diagnosed it as a cracked flywheel or loose torque converter connection.

Mike Bessent · July 18, 2020

At 150 miles mine had the same thumping noise. I was told today that it’s the 2 EGR valves making the noise. At 180 miles now the ticking noise is there too.

ecbello · August 15, 2020

Went to the dealer and test drove the 2020 Silverado 2500HD High Country Dieslel 6.6 Duramax for about 10 miles, and it drove and sounded great on 08.13.20.

Purchased and picked up that same 2020 Silverado 6.6 Duramax Diesel High Country from the dealer on 08.14.20, and drove it 75 miles to my home.

Once I pulled into my driveway, lowered the radio volume and put it in park, it's where I notice the knocking noise. The truck shows 129 miles on the odometer.

I've driven and owned diesel trucks before and never heard a noise like this. It's almost like someone is banging softy on a wooden door with a small hammer.

It's definitely not a diesel engine normal noise. It's not a ticking, wrapping or squealing noise. It's a knocking noise.

Coming from a mechanical and engine rebuilding field, for almost 30 years, this noise almost sounds like the noise I used to hear when there was a worn thrust main bearing on a crankshaft. The crankshaft tends to move back and forth creating a knocking noise every revolution due to excessive clearance. I'm not saying it's a main bearing failure, I'm saying it sounds just like it. I have no idea where the noise is coming from, but it sounds like its more prevalent towards the back of the engine near the bell housing.

The noise tends to increase when accelerating, and definitely sounds louder when you step out of the vehicle.

I was pissed, confused and couldn't sleep thinking as to why such a noise on a new engine and vehicle. I spent 70k with taxes and fees and definitely didn't pay to hear such a noise.

I'm reading and watching videos online, with other people, with the same complaint.

Woke up this morning early to write this, and I will be the first person at the dealer door this morning to attempt to return this truck. I'm will not be buying from their technicians or management that this is normal for these trucks. That seems to be always the case when they want to weasel their way out of a known problem or a warranty issue. The dieseling noise is normal, but not the knocking noise.

I will keep you posted on the outcome.

Listen to noise here. Not my video, but same noise:................https://youtu.be/I4mr0G8cP1w

Xsyourrides · August 16, 2020

I purchased new 2020 Chevy High Country in June this year and had zero knocking noise. Dealership damaged the truck paint and had to buy the truck back and order me new one. I drove the truck as a demo for 5500 kms and 3000 kms of that was towing 15,500 through the mountains with no knocking noise or thumping noise. Picked my new 2020 High Country yesterday , same exact truck. No noise at the dealership, drove it home 90kms backed into the driveway and low and behold the knocking noise was there and in my opinion it was loud enough I could even hear it over the radio. Being a sleepless night pissed right off about why one didn’t have a noise and the exact same truck is knocking . Went out and crawled all over that truck listening, being that I’m licensed HD tech and been dealing with diesels for 30 years I needed to figure it out. After 1 hour of getting nowhere and truck had been idling for hour plus and was convinced that it was not coming from the bottom end, all of a sudden the noise was gone! The engine fan cycled on and noise disappeared. Once the fan kicked out the noise came back. So it kind of goes with earlier statements that it maybe the drive belt. So Maybe a bit of interesting find.

Edited August 16, 2020 by Xsyourrides

Colossus · August 16, 2020

22 hours ago, ecbello said:

Woke up this morning early to write this, and I will be the first person at the dealer door this morning to attempt to return this truck. I'm will not be buying from their technicians or management that this is normal for these trucks. That seems to be always the case when they want to weasel their way out of a known problem or a warranty issue. The dieseling noise is normal, but not the knocking noise.

Well???

Stand By · August 16, 2020

Has anybody specifically listened to the EGR as I've seen mentioned earlier as one possibility. Chrysler had one that was an exceptionally loud design on their 2nd gen Grand Cherokees. Their fix for the engine knocking complaints was to move the EGR to the rear of the body behind the fuel fill. This newer diesel probably has a heavier duty designed one that is also probably very loud. Just thinking out loud.

buelldude · September 3, 2020

whats going on with this thread?

pickmeup · September 3, 2020

Maybe the guy had a bad hearing aid.

Turtlern56 · September 3, 2020

12,000 miles on my 2020 AT4 HD now and it knocks just as loud as ever. Still quiet upon cold start as it was when new then comes on strong and loud. There are very few instances when engine is warm and idling I wont hear it. I still can’t tell exactly what it is. Seems quieter when clutch fan cycles slightly but also could just muffle it a bit to my hearing. Still frustrating as all get out to me. I can hear it over the radio at low volume in closed cab. Just thought I would give my update. I still follow this thread hoping some day somebody finds the fix.

Leningrad · September 13, 2020

Hey everyone- I found my way here as I was trying to find information on the knock on my new Duramax. I just passed 1000 miles and it is still as present as ever and annoying! This is my second Duramax as I came from an 18 Chevy 2500 LTZ and never heard it on that engine? Hopefully we can get a absolute on what it is and if it should be there. I do feel better after coming here as it seems to be a pretty prevalent experience, I guess misery loves company haha!