3.0 Duramax Camshaft Drive Sprocket Replacement

[972sparky]

I watched a youtube of a LM2 teardown after the engine had been replaced due to a failure at around 150K miles. What they found was the cam chains were very loose and the timing of the cams/valves had changed to where the valves were pounding into the top of the pistons, then causing a rod to break in one of the cylinders. Not sure if it had "jumped" some teeth or chain was just too loose. They did not check timing marks during the teardown or if the tensioners were good, all the guides were like new. They also did not measure the chain to see if it was stretched past specs, so could have been any of those problems caused the timing issue. The cam sprockets and the rest of the valve train looked fine though. They did think it may have been caused by chronic low oil level due to some things they found in the lower end but I think that was a symptom, not a cause. On a related note, the dreaded oil pump belt looked like new at 150K, they had to bend it completely back on itself between teeth to see any cracks in it.

To the OP: I would see if they can prove to you that there was no other internal damage due to the exhaust valve timing being off as the valves can hit the top of the pistons. This engine design does not bend valve stems like V engines with canted valves do, so the valve train holds up OK but the pistons take the beating. Just my $.02.

 

[UsualSuspect]

I haven't seen or heard of one failing and we have approx 9 of the 2021's, most have close to, or over 100k. I would think if it were an issue we would hear about it more often. There was a camshaft sensor replaced, but I think that was on the 2019, or 2020's. What I see repair bills for the most are plugged fuel filters, but those are rare. I think we had 1 1500 with a 10 speed have a transmission solenoid act erratically. If there were an issue where we need to schedule downtime to inspect or have it repaired, I would know about that. Most of ours end up out of warranty quickly as they are driven so much. Most of the vehicles we have are from just about any manufacturer due to the shortages a year or so ago, they all have an issue every now and then.

 

[Seamus]

^^^ You have 9 2021 3.0's in service???? If so thats a good barometer?? What oil change interval, and issues are you seeing otherwise?? I look at every carfax i can on higher mileage 3.0's nationwide. No engine work on most everything. Oil changes and filters..thats it.