Bought a new denali 2500hd duramax this week and heard a knocking noise immediately. Service advisor and diesel tech said it was normal. BS I say. It's my 5th diesel. 3 duramax, 1 Cummins, 1 Cat. Knocks at idle cold gets louder when warm. Gets quieter as rpm increases. My stethoscope gets the loudest reading at egr area. A lot of people on this website have also complained about this issue with their new (2020) trucks. Please look at "Engine knock a 500 miles" (that's "a" not "at") 500 miles. On this website...gm-trucks.com Hope you can help us all. Thanks in advance.
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.
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.
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I just picked up my 2020 denali 2500 hd duramax today. This is my third duramax and my 5th diesel. I'm 70 yrs.old and been a tech and shop owner most of my life. Noticed the thump/knock immediately. Went to the salesman and listened to another denali diesel.(new) It was quiet as a baby. Then went to the service advisor and the diesel tech with the same old BS that it was normal and they really couldn't hear what I heard. They said to drive it, and don't worry, it's under warranty. I think someone should post an email address and phone number we can all flood with our same problem. There's safety in numbers and Hopefully,,if they get enough owners complaining, they might get off their butts and do some actual research on the problem. I know GM has changed the lift pumps recently because the Bosch pumps were manufactured for diesel fuel sold in Germany. The problem was that US diesel was thinner which contributed to lift pumps overheating and creating metal shavings that damaged the engines. Maybe these new pumps might be a good place to start. Any updates from the forum are greatly appreciated, and I will update as time goes by. Thanks to all who have taken the time to post so far.
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