3.0 Duramax timing chain stretch and low end knock

[Edward1978]

Have enjoyed this engine but I’m at a loss today. 2020 Silverado with 114k miles,  engine began running rough, developed a knock and “Service Def System” reduced power popped up. Dealer pulled codes and got a P0016 and determined engine timing is off possibly due to a stretched timing chain jumping a sprocket. The timing chain is located at the back of the engine and is an engine out process. Fingers crossed the knock is related and doesn’t require a complete engine. Am I just the unlucky one or is this becoming common as these motors age? 

[Silverado4x4]

54 minutes ago, Edward1978 said:

Have enjoyed this engine but I’m at a loss today. 2020 Silverado with 114k miles,  engine began running rough, developed a knock and “Service Def System” reduced power popped up. Dealer pulled codes and got a P0016 and determined engine timing is off possibly due to a stretched timing chain jumping a sprocket. The timing chain is located at the back of the engine and is an engine out process. Fingers crossed the knock is related and doesn’t require a complete engine. Am I just the unlucky one or is this becoming common as these motors age? 

GM specifies oil pump belt replacement at 150,000 miles and serviced at 100,000 miles, the tranny has to come out to get to the belt, stupid design. Your not alone. It can be done with the engine in. As far as the chain most likely that's what it did. I know they had a TSB problem with the timing sprocket on some motors.

Edited May 22, 2024 by Silverado4x4

[newdude]

I've seen some reports of timing chains on these.  Not a whole lot, but there are reports of it. 

 

Per the service manual, its an engine out job for it, but I've seen GM techs who've done them pull the cab and transmission instead of the engine.  

 

So long as no valves hit pistons, it would need chains, tensioners, guides.  It would also be prime opportunity for the oil pump belt to be tossed on as well.

 

All the chains are in the rear in the 3.0 Duramax, as is the oil pump belt. 

Edited May 22, 2024 by newdude

[Jay P]

1 hour ago, Silverado4x4 said:

GM specifies oil pump belt replacement at 150,000 miles and serviced at 100,000 miles, the tranny has to come out to get to the belt, stupid design. Your not alone. It can be done with the engine in. As far as the chain most likely that's what it did. I know they had a TSB problem with the timing sprocket on some motors.

The newer LM2/LZ0s specify 200k for the oil pump belt and since nothing related has changed that would apply to the earlier models also. If it was mine I would replace it if the engine is apart for the timing chains.

Edited May 22, 2024 by Jay P

[Broberts]

My 2020 just got this report today. Took it in for reduced engine power and lot's of codes. Stretched chains and manifold gaskets is what I was told with some of the parts on backorder. Truck has 92k... It's not time for the pump belt but definitely gonna ask if it can be taken care of while engine/transmission are separated. 

[njodell]

My 2020 with 56K miles....just popped the p016 code....look it up.  Thankfully, I have 4 to 5 months of warranty left.  I'll be getting rid of this, going back to gas.  Lifetime GM guy....new Fords suck as well..may have to look at a tundra for the 1st time ever.  Meanwhile....I'll be minimum 1month without a ride.  I am pissed....GM....would design this sh#$ motor.  Love the mileage....oil pump belt, timing chain.....back of the engine....mind boggling...