Chevy Duramax Diesel Parts

Which Duramax is in your truck?

Several different engines wear the Duramax name on a Chevrolet, and the parts rarely cross over. The 6.6L V8 in the Silverado 2500HD and 3500HD ran as the LB7 from 2001 to 2004, the LLY through 2005, the LBZ in 2006 and 2007, the LMM from 2007.5 to 2010, the LML from 2011 to 2016, and the L5P from 2017 on. The L5P was a clean-sheet engine, not a revised LML, and the 2024 update took it from 445 hp and 910 lb-ft to 470 hp and 975 lb-ft. Away from the heavy-duty trucks, the Silverado 1500 uses the 3.0L LM2 and LZ0 inline-six, and the Colorado uses the 2.8L LWN four-cylinder. Neither is a 6.6L, and neither shares filters, injectors or pumps with one. Chassis-cab 4500, 5500 and 6500 trucks have their own page in the menu above.

What fails, and when

Each generation has its own pattern, and knowing yours saves money. On the LB7 the Bosch injectors sit under the valve covers in brass cups, and they are the defining failure of the engine; most LB7 work starts with pulling those covers. The LLY is the LB7 bottom end with a hotter top end and a cooling system that cannot keep up when the truck is loaded. The LBZ is widely called the most reliable of the family, with trouble limited to injector harness chafe, the 2006 glow plug module, water pumps and age-related leaks. The LMM adds emissions hardware and will crack pistons from the six-hole spray pattern when heavily tuned, though stock trucks commonly reach 250,000 to 400,000 miles. The LML is the one to understand before anything else: its Bosch CP4.2 pump is lubricated only by diesel, and when it lets go it seeds the rails, lines and injectors with metal. The L5P changed that story by giving the Duramax its first factory lift pump and a Denso HP4 pump, so most 2017-and-later complaints are electrical and sensor items rather than hard parts.

Stock replacement or upgrade

For a truck that tows and works, stock-grade replacement is usually the right answer. A failed water pump, glow plug module or injector connector wants the part that GM specified, and ACDelco, Alliant Power and Mahle cover most of that ground. Upgrades earn their place where the factory design is the weak point. On any 2001 through 2016 truck there is no lift pump from the factory, so the high-pressure pump pulls fuel under vacuum and every air leak at the filter head shows up as a hard start. An added lift pump with finer filtration is the standard long-term fix, and on the LML it also protects the CP4.2. Cooling, intake and turbo upgrades follow the same logic: fix what the engine is short of, leave the rest alone.

What we carry

The Chevrolet side of our catalog leans on the brands that build for these engines specifically. Pacific Performance Engineering and Wehrli Custom Fabrication cover coolant, oil and fuel-system hard parts across the whole Duramax run. Merchant Automotive is the first stop for Allison and driveline work. Fleece Performance Engineering and BD Diesel handle fuel and transmission upgrades, AirDog and FASS the lift pump systems, Mishimoto the cooling side, MBRP the exhaust, and BDS Suspension the lift and leveling work. Injectors, filters and fuel additives round it out.

Fitment notes

Model year alone is not enough on these trucks. The 2004 and 2007 model years are both split: an early 2004 is an LB7 and a late one is an LLY, and a 2007 is either an LMM or an LBZ-powered Classic. Single and dual rear wheel 3500 trucks differ in brakes, axles and hitch hardware. Parts listed for a Silverado 2500HD or 3500HD do not carry over to the 1500, which is a 3.0L inline-six, or to the Colorado, which is a 2.8L four. Medium-duty Kodiak and van applications use the same engine families but different chassis, so treat them as separate. Check fitment against your VIN before ordering, or use the checker on any product page.

Frequently asked questions

How do I tell which Duramax I have?

Your VIN carries the engine code, and on the split years it is the only thing that settles it. The build date on the door jamb sticker tells you whether a 2004 is an LB7 or an LLY, and whether a 2007 is an LBZ-powered Classic or an LMM. If you are unsure, call the shop with the VIN and we will tell you what you are working on.

Do you carry parts for the 3.0L Silverado 1500?

Yes. The 3.0L LM2 and LZ0 inline-six has its own section in the menu above. It is a different engine family from the 6.6L, with the timing chains, high-pressure pump drive and oil-pump belt all at the rear of the block, which is why so many repairs on it are transmission-out or cab-off jobs. Do not order 6.6L parts for it.

What should I do first on an LML?

Protect the fuel system. The CP4.2 pump relies on diesel for its own lubrication, there is no lift pump from the factory, and a failure sends metal through the rails and injectors. A lift pump, finer filtration and a lubricity additive are the standard preventive package, and a CARB-numbered CP3 conversion is the heavier option where it is legal for your truck.

Does the Colorado 2.8L need anything on a schedule?

Yes, and it is the one item owners miss. The LWN uses a toothed timing belt on an interference engine with a 150,000-mile replacement interval, so letting it go can cost you the engine. It also runs a complete Denso injection system rather than a Bosch one, so advice written for the CP4 trucks does not apply to it.

Can you install what I buy?

We can. Southern Diesel Supply is a repair shop first, in Wildwood, Florida, and we fit the same parts we list here. If you are local, you can buy and book the work in one go; if you are not, we will still help you confirm the right part before it ships.

Not sure what fits? Call the shop at the number in the header, or use the fitment checker on any product page. We install everything we sell.