General Motors has just announced that it will launch the second generation of its Duramax Diesel engine in 2023 for select Chevrolet Silverado 1500 and GMC Sierra 1500 pickups. This is the first change for the LM2, now named LZ0, turbo engine six-cylinder diesel since its introduction in 2019. GM says 25% of the engine has been completely redesigned, increasing power to 305 hp and torque to 495 lb-ft. So, will these changes improve both performance and reliability?
Why is the extended inspection time of Duramax diesel a big problem?
GM is confident enough in the reliability of the new LZ0 Duramax engine to extend its recommended inspection to 200,000 miles. The importance of this is enormous. This is because in the previous generation you had to drop the transmission to replace the variable valve oil pump belt at 100,000 miles. It is located at the rear of the crankcase. Yeah, not the best design.
And another improvement concerns one of its biggest problems, boot problems. Many owners have complained that it takes a long time for the Duramax to start. That, or it won’t start at all. The solution was to give it a few seconds rest and then try again. Eventually it would ignite.
Has GM fixed the Duramax diesel engine starting problems?
GM engineers spent a lot of time on starting issues. Supplier-damaged camshaft position sensor exciter wheels, or trigger wheels, were the culprit. In 2021, a Technical Service Bulletin (#PIP5806) announced the issue. The trigger wheel would become bent, requiring replacement.
But they also discovered that some of the trigger wheel teeth were also twisting. So the solution involved a different crank design to improve tooth engagement on the LM2 engines. The new LZ0 Duramax also received this fix. So, the mystery of boot/boot issues has finally been solved.
Another durability improvement concerns the pistons. Previous generation LM2 engines used aluminum pistons. The new LZ0 uses smaller steel pistons. Why smaller? GM diesel engineer John Barta told Pickup Truck SUV Talk that’s because it adds a longer stroke while maintaining the 3.0-liter displacement.
How did GM improve Duramax diesel power?
Another change is to use new injectors to help increase turbocharger tuning. This increased his power. And big change with a completely redesigned cylinder head. Beyond these changes is a redesigned cooling system.
For 2023 GM trucks, the new Duramax diesel engine will only be available in Custom Trail Boss, LT, RST, LT Trail Boss, LTZ and High Country trim levels. It will not be available in the ZR2 or ZR2 Bison. Additionally, Chevrolet Tahoe/Suburban and GMC Sierra/Yukon SUVs will also receive the new Duramax. But that will only happen after 2023.
You can also refer to this article for information on typical LM2 Duramax diesel engine problems.
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