The Duramax Generations Throughout the Years

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For a long time, diesel engines were used only in heavy equipment. It wasn’t until the 1970s that they began to find use in light trucks and personal vehicles. General Motors didn’t put a diesel engine into a truck until 1982, and turbocharged diesel engines didn’t show up until the mid-1990s. In other words, diesel engines in passenger vehicles don’t have as long of a history as you might imagine.

The first GM diesel for trucks was the Detroit Diesel and it hung around until the first Duramax engine was released in 2000. To develop the first Duramax, GM collaborated with Isuzu and came up with a 6.6-liter turbocharged V8. There have been several Duramax generations since the first one. Let’s take a look at each one.

Duramax LB7: 2001-2004

The LB7 Duramax was a 32-valve engine with a cast iron block and common rail direct injection. It also featured aluminum cylinder heads with four valves per cylinder and 17.5:1 compression. The LB7 initially made 235 horsepower and 500 pound-feet of torque, but by the end of the generation, it made 300 horsepower and 520 pound-feet of torque.

Compared to other Duramax generations, the LB7 is unique in that it uses a fixed-geometry wastegate IHI turbocharger. The main problem with this engine is injector failure, which is known to happen around 150,000 miles.

Duramax LLY: 2004.5-2005

This Duramax generation has the distinction of being the first one that GM equipped with emissions control. The LLY uses a Garret variable-geometry turbocharger with an EGR system. As a mid-cycle refresh, this engine only saw a small jump in output to 310 horsepower and 520 pound-feet of torque.

Common problems with the LLY Duramax include head gasket failure, overheating due to a restrictive air intake, and glow plug failure. The latter problem is particularly concerning as the plugs can actually break apart inside the engine.

Duramax LBZ: 2006-2007

The LBZ Duramax wasn’t out very long, but it’s considered to be the best Duramax diesel. It featured a robust block, a lower 16.8;1 compression rate, and thicker connecting rods. The LBZ is also the last Duramax engine that doesn’t have diesel exhaust fluid.

The sturdier engine design and better emissions control led to the LBZ making up to 360 horsepower and 650 pound-feet of torque. It had very few major issues, but it was known to experience water pump failure between 80,000 and 100,000 miles.

Duramax LMM: 2007.5-2011

The LMM ushered in the era of high-powered Duramax engines in passenger trucks. This engine uses a variable geometry turbo and features new tuning, EGR, and low-ash oil. The updated cylinder heads include better water passages for improved cooling.

However, the LMM was also the beginning of stricter regulations for diesel emissions and thus came equipped with a DPF to keep this in check. The DPF regeneration cycle can lead to excessive cylinder wear and fuel diluting the engine oil. The LMM Duramax made 300 to 365 horsepower and 520 to 660 pound-feet of torque.

Duramax LGH: 2010-2017

The LGH Duramax engine was a version of the LMM that was used mainly in vans and box trucks. Like the LMM, it was virtually identical to the LBZ engine, except with a new DEF system.

Unfortunately, the DEF system wasn’t all that great. It was prone to causing various mechanical failures and it also reduced fuel economy. This engine was capable of 335 horsepower and 685 pound-feet of torque.

Duramax LML: 2011-2016

The LML Duramax is essentially a higher-powered version of the LMM. The emissions system had some improvements, including the injection of raw diesel into the exhaust to help the DEF do its job. Internal engine components were ironed out from previous problems and feature lighter and stronger rods and pistons.

The stock engine made 397 horsepower and 765 pound-feet of torque but can support up to 700 horsepower after tuning. The biggest problem with this engine was the fuel injection pump, which can fail without warning.

Duramax L5P: 2017-2023

The L5P Duramax improved on the previous engine with a beefier block, a new cam design, improved glow plugs, and a larger oil cooler. The EGR system also received a significant upgrade and the DEF system was much improved over previous versions.

The L5P engines are capable of making 445 to 470 horsepower and 910 to 975 pound-feet of torque. The main issues with this engine are glow plug failure and DEF failure if it’s not regularly maintained. A more powerful Gen2 L5P was introduced for 2024 model HD trucks.

3.0-liter Duramax LM2: 2019-2023

GM has also made a smaller 3.0-liter Duramax engine for use in the GMC and Chevy midsize pickups. The first generation of this engine is known for being incredibly fuel-efficient and effectively made GM’s smaller trucks the most fuel-efficient you could buy.

The LM2 Duramax made 277 horsepower and 460 pound-feet of torque. It could tow up to 9,300 pounds and get up to 33 MPG on the highway.

3.0-liter Duramax LZ0: 2023-

The LZ0 Duramax is the second generation of the inline-six turbodiesel engine colloquially called the “baby Duramax”. The LZ0 engine is fairly similar to the LM2, but it kicks up the output to 305 horsepower and 495 pound-feet of torque. Fuel economy and towing capacity are basically the same as the previous engine.

When you need parts or upgrades for your Duramax diesel engine, you can rely on ProSource Diesel for a wide variety of quality parts, kits, fluids, and more. We are where the diesel repair shops shop for diesel truck parts.

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