Engine knock a 500 miles

Colossus · September 14, 2020

I hope you can find help for your new one. You might check over at duramaxforum.com as there are more diesel owners over there if you don't get anything on here. How did your 2018 work out for you? I'm considering upgrading to a 2018 from my 2008. Most of the DPF and DEF issues were resolved for 2018 and 2018 doesn't have the dreaded CP4 fuel pump issue.

Hoss sharifi · September 25, 2020

Just picked up a 2020 silverado this morning. I have been reading this thread and another so when I got to the dealer I started the truck and the knock was there but not too bad. Drove 60 miles home (truck has 90 miles on it right now) and when I got home I opened the door with it running and it was much louder and its not a ticking noise definitely a "thumping" sound and it seems to be towards the rear of the motor. I dont like the noise but with so many saying the same thing I am not going to worry about it. If it were something major I would think GM would send out a recall, being a new model I am sure they want to protect their new baby. Other than the thump love the truck the motor feels smoother than my 19 ram 2500.

bsmall1564 · September 25, 2020

Congrats on your new 2020 Hoss. I feel the same as you regarding the noise I get from mine.

I’ve put on about 6K miles towing without any issues, so I’m assuming if it were a major issue it would have shown up by now.

Still love it!

buelldude · October 14, 2020

I still keep looking for anything on this from GM, nothing. I did come across something other than the belt removal. I was watching part of the banks videos on YTUBE. The oil cooler is bigger with more cooling coils and its on the back of the engine. I'm not saying that is what it is but it is a new part put on the 20's. I have been looking at what the differences are and what could be making the noise. I started to think that cold oil going thru the cooler may not make the noise till it warms up and makes it till it cools down. Till its cold again and I don't get it when its cold. I will think things thru, that is till I either give up or find the issue. I have emailed a few places with questions and ideas and most of the time I get nothing in return????

Edited October 14, 2020 by buelldude

Walkerman · November 1, 2020

2020 GMC 3500HD. Yeah, mine sounds like that. 10k miles. Great video.

David Nichols · November 24, 2020

I just bought a 2021 same problem the knock is annoying as hell my 18 did not do this and same thing the dealer says it normal I have 80 miles on this thing I’m not happy at all

combat1500 · November 27, 2020

On 11/23/2020 at 4:16 PM, David Nichols said:

I just bought a 2021 same problem the knock is annoying as hell my 18 did not do this and same thing the dealer says it normal I have 80 miles on this thing I’m not happy at all

I know the feeling man... We need to get a petition going.

Crazy how everyone gets home with a brand new truck from the dealer and hears the loud knock.

BernieDoodle · November 29, 2020

I just bought a brand new 2021 Duramax Z71. There was someone else on the way to look at it and I had to act fast. All local dealers were selling them as soon as they came in. The dealer I bought it from was on a busy highway with a lot of noise. When I got it home I noticed a knocking noise. I took it to three local Chevy dealers and had mechanics listen to it. It is pretty loud and obvious but they would not say it was abnormal. To me this is unacceptable. I noticed there is even a bulletin about it online. This is a $70,000 plus vehicle. Come on GM. What are you going to do about this? There should be a recall or something. Sounds like I'm not the only one unhappy about this.

Colossus · November 29, 2020

It is normal to them so obviously they are not going to do anything. Trade it in on a Crapota I guess??

Kevin McCue · December 8, 2020

[email protected]

My 2020 duramax has the horrible loud knock noise, started at 350 miles. So far GM is calling it normal, but calling it normal does not make it right. I am not satisfied or happy, hoping for better.

Goomba · December 11, 2020

I also recently purchased a 2020 3500 and I have 7116 miles on it already and I have been hearing this knock sound and took it to the first oil change and i feel like it just got louder. Hate the sound but i can live with it it’s just embarrassing to park next to all my guys having the newest truck and all of them asking what’s wrong with your truck having problems already.

mrjulian416 · December 13, 2020

I think this is the bulletin related to this sound. "Normal" according to GM.

L5P knocking sound from back of engine.

dipstick · December 13, 2020

Have any of you guys changed your oil yourself? Well I just changed mine at 3200 miles 2020 Duramax. When I fired it up that knock/thump sound just multiplied about 20X until the oil filter filled up and oil started to circulate. Way more noise than any oil change I've ever done It sounded like a knock and not a thump at that point. I felt like damage was in progress while waiting for oil pressure to build. Change the oil filter to hear for yourself.

Tomato · December 13, 2020

2 hours ago, dipstick said:

Have any of you guys changed your oil yourself? Well I just changed mine at 3200 miles 2020 Duramax. When I fired it up that knock/thump sound just multiplied about 20X until the oil filter filled up and oil started to circulate. Way more noise than any oil change I've ever done It sounded like a knock and not a thump at that point. I felt like damage was in progress while waiting for oil pressure to build. Change the oil filter to hear for yourself.

That is not encouraging...I think we all agree that the sound is there for a second at cold start up, then oil pressure builds and it quiets until the engine is warm. Oil pressure is highest when cold, obviously. Definitely seems to tap at engine/crank RPM/speed as well.

I am shocked that no one here on the forum has posted definitively about the belt removal test. A before and after video would be great.

I had emailed Banks a long time ago given their intimacy with the Duramax - never got a response...Pissed me off, as I am a customer, and that request got me added to their email ad list, but never got a response to my inquiry. Thanks, Banks.

bsmall1564 · December 13, 2020

12 hours ago, dipstick said:

Have any of you guys changed your oil yourself? Well I just changed mine at 3200 miles 2020 Duramax. When I fired it up that knock/thump sound just multiplied about 20X until the oil filter filled up and oil started to circulate. Way more noise than any oil change I've ever done It sounded like a knock and not a thump at that point. I felt like damage was in progress while waiting for oil pressure to build. Change the oil filter to hear for yourself.

That's exactly what I experienced when I changed my oil & filter. So I thought just maybe the AcDelco Filter wasn't doing a very good job related to the pressure creating the noise. So the next oil & filter change I used an AmsOil filter and was a little quieter regarding the thumping/knocking noise upon start up, but was still present. So the following oil change I went back to using the AcDelco.

I just figure its just a characteristic trait to the L5P Engine. Currently I have about 10K miles of towing with it and everything is great.

Edited December 14, 2020 by bsmall1564
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