LM2 Valve Clatter

[LM2HC4x4]

New to the forum.

Picked up my LM2 end of January. Began having what sounded like valve clatter around around 2k rpm. Assumed, it was potentially normal as the engine continued to break-in. However, it has continued to get worse. The dealership has opened a "Tact" case no answers at this stage as there are apparently no others issues like it. At cold start yesterday morning (about 30F degrees) definitely had more like an engine rod or main bearing knock.

The dealership diesel tech originally though it was normal diesel sound but has know come to the conclusion there is definitely an internal engine knock.

Will keep posted as we get more information. I will be dropping the truck off this coming Monday for continued test.

If anyone knows of anyone with the same issues. Let me know!

Thanks,
Richard

 

[TheBac]

Moved this into your own thread in LM2, so it doesnt get lost.


Welcome to DD.

 

[KyleC4]

I have not heard anything yet of issues like what you are describing. And yes the “TAC” (technical assistance center) for GM is contacted for all new model vehicles. Engineering usually gets involved and wants to know. Could be a long road just so you know. Hang in there.

 

[jp2000]

I also have this clatter on my 3.0 LM2.

Gets pretty loud when slowly climbing hills. Going slow in a parking lot I can mostly avoid it happening.
Sometimes right after cold start up if I put it in fwd or reverse with the parking brake on to hold it, it will clatter away while I search relentlessly.
Sometimes after it gets warm and I get to my destination and I park I can hear it intermittently clacking. (not the typerwriter kind that plagues other engines)

Its loud enough to feel embarrassing coming out of your new truck, doesn't sound like part of the diesel sound. Like you I hope it will go away (not likely). I haven't had time to take it to the dealer yet.

 

[jp2000]

Was watching this guy's youtube and can kinda hear much of the same clatter noise on his startup. Is that what yours sounds like?

Not sure how to link vids, start up is at 49 seconds, real clatter comes in at 1:02

https://youtu.be/fRVjTby4cIs?t=49

2020 Silverado 3.0 Duramax Cool Weather features, startup and warm up (16F to 20F)

 

[TheBac]

Could it be that GM set the valve lash too loose on those engines, or an adjuster nut has backed off in the valvetrain as you've put miles on?

 

[Chevy1925]

Was watching this guy's youtube and can kinda hear much of the same clatter noise on his startup. Is that what yours sounds like?

Not sure how to link vids, start up is at 49 seconds, real clatter comes in at 1:02

https://youtu.be/fRVjTby4cIs?t=49

2020 Silverado 3.0 Duramax Cool Weather features, startup and warm up (16F to 20F)

thats not valve clatter. thats fuel knock from either being real cold or lots of timing from it being so cold

 

[jp2000]

Yeah, that's a reasonable explanation. The problem is mine just makes noises like this when warm under light load.

Here's another more obvious clatter that is way easier to hear that sounds like my clatter.

https://youtu.be/C6Ug6AS9Le0?t=67

But once again this guy is cold start. If you heard this clatter under warm temperatures after the engine was warmed up, most noticeable under load, what do you think the problem would be? When he comes back from his drive, I can still kind of hear the abnormal clatter.

 

[Chevy1925]

I don’t know what you are expecting. I just hear a Diesel engine. You can’t expect it to be as quiet as a gasser

 

[fast03]

thats not valve clatter. thats fuel knock from either being real cold or lots of timing from it being so cold

Or even warm under light load. pilot injection / timing rattle.

 

[jp2000]

Yeah, I've been thinking funky pilot injection. Sadly I don't see any relearn procedures for that with gds2, seems to help some cars. Still need to verify they put the right injector codes in at the factory. Wonder if they could even mess that up if they wanted to. These things are just probably extra clattery.

Thanks fast03

 

[Seansmp8]

I have the same rattling sound. It only started after the dealer replaced my coolant control valve. It’s so damn irritating.

 

[Cansomike]

New to the forum.

Picked up my LM2 end of January. Began having what sounded like valve clatter around around 2k rpm. Assumed, it was potentially normal as the engine continued to break-in. However, it has continued to get worse. The dealership has opened a "Tact" case no answers at this stage as there are apparently no others issues like it. At cold start yesterday morning (about 30F degrees) definitely had more like an engine rod or main bearing knock.

The dealership diesel tech originally though it was normal diesel sound but has know come to the conclusion there is definitely an internal engine knock.

Will keep posted as we get more information. I will be dropping the truck off this coming Monday for continued test.

If anyone knows of anyone with the same issues. Let me know!

Thanks,
Richard

I have the same issue and I’m thinking it’s injection/combustion related. I still don’t like it though, especially coming from a new truck. I have to have a faulty coolant valve replaced this week and I’m going to mention it to the dealer.

 

[steelman02]

Hello all, I'm new to the forum.

I am having the same issue with the clatter, or sometimes knocking noise at low throttle. I have tried getting fuel from different stations to see if that would have any affect on it, but that made no difference. At times the knocking noise is very loud like a rod or something.

 

[NC-smokinlmm]

Has anybody tried a fuel additive yet? Diesel power service makes my LML so quiet you'd think its a gasser. I'd give it a shot, it's cheap and easy.

 

[Savagetribe]

Replaced my coolant valve because of defect from manufacturer and now valve clatter. Took to dealership and they said probably fuel related. Top Tier is what Chevy recommends for diesel standard but no fuel stations have it. Also, additive is not available for purchase from parts stores. I added one that a lot of diesel truckers use to increase efficiency and performance. It reduced severity of the clatter. Can someone post if they found a fix for this issue?

 

[Savagetribe]

I have the same rattling sound. It only started after the dealer replaced my coolant control valve. It’s so damn irritating.

Same here. Something is not right. Sounds like a 250,000 mile diesel rather than new. I've owned diesels in the past and this is a problem GM needs to fix.

 

[Savagetribe]

Has anybody tried a fuel additive yet? Diesel power service makes my LML so quiet you'd think its a gasser. I'd give it a shot, it's cheap and easy.

Added Max-Tane diesel additive. Seems to help reduce clatter but not fully.

 

[Savagetribe]

Has anyone took your Duramax 3.0l truck in for the new tech bulletin just posted? They say idol rattle is because of the intake system is loose. I took mine in but didn't fix the clatter in the engine. It just fixed the idol rattle.

 

[LiveWire]

Hello to everyone ,I am new duramaxdiesels.com

To start off the LM2 3L is my first diesel so I’m not familiar with the characteristics of a Diesel engine .
That being said I also am having valve clatter at low speed going up a small hill in to my neighborhood.I also notice it on light acceleration around the end of the shift point then stops.I bought it as a demo with 5000 miles on it I’m up to 10,000 miles now and I’m noticing it a little more I haven’t had it back to the dealer yet but I’m wondering if this is normal for this motor.