If you’re shopping a used Silverado or Sierra diesel, the 3.0 Duramax problems you read about online aren’t spread evenly across its life. They cluster by generation: long cranks and rear main seal leaks on the 2020–2022 LM2, and crankshaft thrust bearing failures on some 2025–2026 LZ0 engines. Our take: a 2023–2024 LZ0 is the one to buy, and the feared rear timing chain is mostly a repair-cost problem because of where it sits.
Quick answer: The most common 3.0 Duramax problems are long cranking and rear main seal leaks on 2020–2022 LM2 engines, and crankshaft thrust bearing failures on some 2025–2026 LZ0 engines covered by GM bulletin 25-NA-307. The rear-mounted oil pump belt and timing chain rarely fail, but replacing either means pulling the transmission.
Last updated: November 3, 2026
3.0 Duramax problems by year: which engines are affected?
GM has built two versions. The LM2 arrived in 2020 Silverado and Sierra pickups with 277 hp and 460 lb-ft, per PickupTruckTalk. The LZ0 replaced it for 2023 at 305 hp and 495 lb-ft. GM assistant chief engineer John Barta told PickupTruckTalk’s Tim Esterdahl that about a quarter of it was redesigned, including steel pistons.
| Engine | Model years | Output | Main reported problem | GM response |
|---|---|---|---|---|
| LM2 | 2020–2022 | 277 hp / 460 lb-ft | Long crank or no-start; rear main seal leak | Software update; bulletin 22-NA-022 |
| LZ0 | 2023–2024 | 305 hp / 495 lb-ft | Oil use when towing; rear main seal leaks | Treated as normal or repaired case by case |
| LZ0 | 2025–2026 | 305 hp / 495 lb-ft | Crankshaft thrust bearing failure (code P06D) | Bulletin 25-NA-307; no recall |
LM2 problems: long cranks and the rear main seal
The long crank was the LM2’s signature complaint, with owners in Jalopnik’s September 8, 2025 roundup waiting 10–20 seconds for a start. Barta explained the cause to PickupTruckTalk: a supplier shipped slightly bent exciter wheels, which confused the sensors that tell the computer where the crankshaft is. GM’s fix was software that lets the engine turn one extra revolution before injecting fuel, adding about four-tenths of a second to each start.
The oil leak costs more. GM’s February 2022 bulletin 22-NA-022, filed with NHTSA, says the rear main seal can shift out of position in the lower timing chain cover, sometimes setting code P06DD. The repair is a new cover with the seal already installed. Because that cover sits at the back of the engine, the transmission has to come out.
On a used LM2, ask a GM dealer for the service history by VIN. A truck that already got the new cover has had its biggest weakness fixed.
Is LM2 engine timing chain failure common?
Not in the records we checked. Our November 2, 2026 search found no NHTSA recall or GM bulletin for LM2 timing chain failure. The issue is location. The timing chain and the oil pump drive belt both sit at the rear of the engine against the transmission, and Getty’s Garage mechanic Alex said in a review Diesel Army covered in January 2026 that replacing the chain means removing the transmission.
The oil pump belt matters more for your budget because it’s on a schedule. It’s a rubber belt that runs wet in engine oil, and GM’s interval is 150,000 miles on the LM2 and 200,000 on the LZ0, per Diesel Hub’s maintenance schedule and Barta. Barta said GM chose a belt over a chain to meet a cabin noise target, after research showed buyers wouldn’t accept a loud diesel.
Esterdahl put the job at $1,000 to $2,000 a few years ago, and on June 30, 2026 he cited a Demonworks mechanic’s newer quote of $3,000. An LM2 showing 140,000 miles is 10,000 miles from a transmission-out service, so take that cost off your offer.
Duramax LZ0 engine problems: the 2025 thrust bearing failures
This is the serious one. GM bulletin 25-NA-307, dated October 1, 2025 and reported by PickupTruckTalk, covers 2025–2026 Silverado, Sierra, Tahoe, Suburban and Yukon models with the LZ0. It tells technicians to listen for noise behind the bell housing and to check for code P06D, which flags insufficient crankshaft end play.
The thrust bearing stops the crankshaft from sliding forward and back in the block. When its surfaces are out of spec, the crank moves too far, metal hits metal and the engine can fail with little warning. PickupTruckTalk says the problem appears limited to trucks built between early and late 2025.
There’s no recall, so nobody will mail you a notice. If you own or are buying a 2025 or 2026 diesel, ask a GM dealer to measure crankshaft end play with a dial indicator and keep the printout. You may pay a diagnostic fee if the truck has no symptoms.
Two smaller LZ0 habits matter. GM treats a quart of oil every 1,000 miles while towing as acceptable, which Alex said he “strongly” disagrees with. Trucks that mostly idle or make short trips clog their particulate filters sooner, because the filter needs sustained heat to burn off soot.
How does 3.0 Duramax reliability compare with GM’s gas V8s?
It holds up well. GM recalled the 6.2-liter L87 V8 (see our 6.2L recall guide), and PickupTruckTalk notes ongoing lifter failures on the 5.3-liter, which we cover in our Silverado engine problems guide. The diesel’s thrust bearing trouble is real, but it’s tied to a production window rather than the whole run of the engine.
Running costs are a different story, and the EPA ratings for the 2026 Silverado show the trade.
| 2026 Silverado 1500 engine | EPA city/hwy | Combined | EPA annual fuel cost |
|---|---|---|---|
| 3.0L Duramax diesel (2WD) | 23/28 mpg | 25 mpg | $3,750 |
| 2.7L TurboMax four (2WD) | 18/21 mpg | 20 mpg | $3,200 |
| 5.3L V8 (2WD) | 16/20 mpg | 17 mpg | $3,800 |
| 6.2L V8, premium fuel (4WD) | 15/20 mpg | 17 mpg | $4,700 |
The diesel burns the least fuel, yet EPA expects it to cost $550 a year more to fuel than the 2.7-liter four, because diesel costs more per gallon in EPA’s figures. Buy the 3.0 for torque and towing range. GM Authority lists its 2026 tow rating at 13,300 pounds, the highest in the lineup.
Which 1500 Duramax should you buy?
For a used truck, target a 2023 or 2024 LZ0. It has the stronger internals and the 200,000-mile belt interval, and it sits outside the thrust bearing window. A 2025 or 2026 is fine if the end-play check comes back in spec or the engine was already replaced. Buy an LM2 only at a price that covers the belt service, with bulletin 22-NA-022 work on record.
Buying new? Chevrolet’s 2027 Silverado release carries the LZ0 over at the same output and adds it to the Work Truck. GM hasn’t said whether 2027 engines include changes tied to the thrust bearing issue, so ask for the build date. The 2027 chart cuts the diesel’s max tow rating to 12,000 pounds. Need more? Our 6.7 Cummins guide covers a three-quarter-ton option.
3.0 Duramax questions owners ask
What year 3.0 Duramax should you avoid?
Be most careful with 2025 and early 2026 LZ0 engines, which GM bulletin 25-NA-307 ties to crankshaft thrust bearing failures, unless end play has been measured or the engine replaced. Early LM2 trucks need proof of the long-crank software update and the rear main seal repair. The 2023–2024 LZ0 has the cleanest record.
Does the 3.0 Duramax have a timing belt or chain?
It has a timing chain, mounted at the rear of the engine next to the transmission. What owners often call the timing belt is the separate oil pump drive belt, a rubber belt that runs in oil. GM schedules its replacement at 150,000 miles on the LM2 and 200,000 miles on the LZ0, and both jobs mean removing the transmission.
How much does it cost to replace the 3.0 Duramax oil pump belt?
PickupTruckTalk’s Tim Esterdahl put the job at $1,000 to $2,000 a few years ago and wrote in June 2026 that a well-known diesel mechanic now quotes about $3,000. Most of that is labor, because the transmission has to come out to reach the belt at the back of the engine. Shop rates change the final bill.
Most 3.0 Duramax problems carry a date stamp, which is good news when you’re buying. Read the build date first, then check the odometer against the belt interval, because 150,000 miles on an LM2 means a transmission-out service. Get past those and a two-wheel-drive diesel Silverado earns 25 mpg combined from the EPA, a figure no gas engine in the 2026 Silverado lineup matches.