LM2 Valve Clatter

Savagetribe

New member
Feb 25, 2021
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I took my diesel in again and they did diagnostics. Everything running as normal and they said the clatter is a normal thing for all the 3.0L Duramax diesels. I told them it's lazy engineering and would like Chevy to rectify. This is louder than any diesel I've had and driven.
 

LiveWire

New member
Mar 28, 2021
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With my main concern being excessive wear over the life of the vehicle on the valves and valve seats
 

Silverado21

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Mar 28, 2021
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I also had what sounded like valve noise during light acceleration. It seemed to get worse the closer to a regen it got. I had to bring the truck in to the dealer for a bad battery, and had them do an oil change( first one) while there. On my way home after picking it up, I noticed on my paperwork that they put 6 quarts of 5w30 dexos in my truck. Turned around and went strait back to the dealer and told them they put in the wrong oil. Dealer looked up my vin on their computer, and 5w30 dexos was listed as the correct oil. I showed them the manual, and the oil cap on the truck shows 0w20 dexosD. Dealer called GM, and it was determined that the info in the computer was wrong.(How the he** does that happen). After another oil and filter change with the correct oil, no more valve clatter!! Maybe the oil that was originally in there was wrong also?
 

LiveWire

New member
Mar 28, 2021
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Similar to what Silverado 21 had I tried to purchase a couple quarts of 0W 20 Dexys D just to Keep in my truck for emergencies and the Worker in the service department of the dealership tried to sell me decos Gin to to as compatible oil
 

LiveWire

New member
Mar 28, 2021
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That’s scary Silverado21, when I picked up my truck it had 5000 miles on it as a demo I had them change the oil and have put another 5000 on it .when I tried to get the service records from the dealership thinking they may have done the same thing they assured me they used the correct oil but were changing computer programs and couldn’t access the records as I mentioned above Neither the parts department nor the service department were very familiar with 0W 20 Dexos d I’m going to take it in for an oil change Monday morning first thing if that stops the rattling someone’s going to have to answer some serious questions about the longevity of my motor in the warranty
 

Orion

New member
May 8, 2021
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New owner here, got about 1000 miles on the truck and noticed the knocking at low rpms this morning after a few miles of driving. Went away at higher rpms. Louder than normal diesel knocks in my experience.
Based on what you guys have said, GM has said this is normal though?
 

LiveWire

New member
Mar 28, 2021
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I haven’t had a chance to get mine back into the shop but I’ve talk to the service manager at a different GMC dealership and was told the sound was normal coincidently I just spoke to another Duramax LM2 owner this morning amd he has a little valve clatter at low RPMs and low speed just the same.It may just be me but I feel like mine is a touch more than a little rattle. I plan on taking it in next week then I will post the response from the dealership where I purchased it.
 

Orion

New member
May 8, 2021
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Cool, well I will reply to this in the future if it continues and if I take it in. Let us know if you find out anything. Kinda wishing I bought the extended warranty at this point lol.
 

LiveWire

New member
Mar 28, 2021
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Because it was the first year this motor came out I decided to purchase the extended warranty the 100,000 mile 10 year
 

LiveWire

New member
Mar 28, 2021
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Update on my valve clatter Concern. I took my 2020 Sierra in for a clunk in the driver side Leafspring (for the second time) to find out there is a wide spread problem causing a 2 month back order of the required parts to fix it. which I quickly discover after only a few minutes on the internet ... so to make a short story even longer they had 2 Different diesel techs drive my truck and found that it is normal for the 3L LM2 to have some valve clatter at low speeds/ light acceleration and it was no different than any other 3L diesel the have had come in...
 

LiveWire

New member
Mar 28, 2021
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Wow sounds like I may need to try another dealership for a second opinion thanks for the info
 

Orion

New member
May 8, 2021
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Wow sounds like I may need to try another dealership for a second opinion thanks for the info

I believe the injector relearn is a temporary fix. Have the dealer open a TAC case for you. Hopefully GM fixes the issue in the future but for now it doesn’t sound too harmful based on what I’ve read.
 

LiveWire

New member
Mar 28, 2021
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That’s good news if it’s non harmful and I will be looking into this I appreciate the heads up