2007.5-2010 Chevy Duramax LMM Parts & Upgrades

The LMM on the 2007.5-2010 Silverado 2500HD and 3500HD

Mid-2007 the HD pickups moved off the GMT800 body onto the all-new GMT900 chassis and cab, and the LBZ gave way to the fourth-generation Duramax, the LMM. Power barely moved: 365 hp at 3,200 rpm and 660 lb-ft at 1,600 rpm, against 360 and 650 for the LBZ. The real change was the emissions hardware the 2007 federal standard required, a diesel oxidation catalyst, a diesel particulate filter that burns its own soot out with late post-injection, an enlarged EGR cooler and closed crankcase ventilation. There is no DEF or SCR on this truck; urea injection arrived with the 2011 LML. GM also reinforced the block casting and main bearing material, used thicker connecting rods and larger piston pin bores, added cooling capacity, and specified low-ash CJ-4 oil. Fuel still comes from a valley-mounted Bosch CP3 at 26,000 psi through Bosch common-rail injectors, air still comes through the water-cooled Garrett GT3788VA variable-vane turbo and an air-to-air intercooler, and every LMM pickup left the line with the Allison 1000 six-speed. Chassis cab versions over 10,000 lb GVWR were rated lower from the factory, in the 312 to 322 hp range, so check the rating before you compare two trucks.

What fails and why

Most of what brings an LMM into our bays in Wildwood traces back to aftertreatment heat and the soot that comes with it.

• DPF loading. Short trips, long idling and heavy towing interrupt regens, and ash never burns off, so the filter eventually needs cleaning or replacement. You see frequent regens, a clean-exhaust-filter message, P2463 and reduced power or limp.
• Exhaust leaks upstream. The passenger-side up-pipe flex bellows cracks with age and heat cycling, and cracked manifolds, loose flanges and dead gaskets do the same thing. Expect a metallic tick or screech under load, soot streaks, lost drive pressure and higher EGT, plus extra regens, because a leak confuses the DPF pressure and temperature sensors.
• VGT vanes sticking. Carbon builds on the vanes, pivots and unison ring, and DPF backpressure plus EGR soot makes it show up earlier on an LMM than on an LBZ. Codes run P0299, P003A, P2563 or P0234, and the truck has strong low-end with no top end or the reverse. A dead actuator or a sensor-wiring fault fakes the same symptoms.
• Charge-air leaks. Oil film from the closed crankcase system coats the boots, clamps lose their grip, and a coupler blows off with a pop and instant power loss or hisses under boost with oily dust at the joint. It gets misread as turbo failure constantly.
• Fuel supply. There is no factory lift pump; the CP3 pulls its own fuel, so a tired filter, a cracked primer or a seeping filter-head seal starves it. Low rail pressure, P0087, shows up first under summer towing load.
• Allison wear points. Factory cooler lines leak at the hose-to-hardline crimp, sometimes very early in a truck's life. Once power goes up, the stock torque converter is the first casualty and the C3 clutch pack is the clutch that burns.
• Cooling and oil. Water pumps seep at the weep hole as they heat-cycle, debris packed between the intercooler and radiator delays fan-clutch engagement, and post-injection regens dilute the oil with fuel. Overheating is what kills head gaskets on these engines.
• Front end. Pitman and idler arms wear and let the center link move, and it goes faster on a leveled truck with large tires.

Stock replacement vs. upgrade

If the truck is stock and you want it to stay that way, put the mechanical control points back with OEM-style parts: water pump, thermostats and fan clutch together, with fresh coolant at the same time. Constant-tension clamps or a complete intercooler hose-and-clamp kit cover a one-off boot failure. A filter on schedule, with the filter-head seals and primer inspected, comes before anyone chases rail pressure. A carbon-stuck VGT can be cleaned rather than replaced, out of the truck with the turbine side apart, vanes and unison ring cleaned and high-temp anti-seize on reassembly, and upstream exhaust leaks get fixed before a turbo is condemned for lag. Upgrade where the factory design is the limit. A frame-mounted lift pump with added filtration steadies supply and takes load off the CP3 and the injectors; keep its feed pressure modest, roughly 10 psi or less. A heavy-gauge stainless up-pipe with a welded bellows ends that repair for good. A 3 in Y-bridge and cold-side pipe kit with reinforced boots and T-bolt clamps stops repeat blow-off, keeps the EGR and grid-heater connections and needs no tuning. For towing, finned differential covers add fluid and cooling on the AAM 11.5, and air helper springs control squat. If you add power, tune the Allison TCM alongside the ECM, keep the total near 430 to 450 rwhp on a stock transmission, and watch EGT, because aggressive timing cracks LMM pistons around 600 hp. ARP head studs with the late riveted-style gasket are the rebuild spec for a truck that tows.

What we carry

Fuel-system work is covered by FASS lift pumps and water separators, Pacific Performance Engineering lift pumps and oil filtration, Exergy Performance injection components, and filters from ACDelco and S&B. Merchant Automotive supplies the small parts that make a repair come out right, including intake tube seal kits, water-in-fuel sensor o-rings, coolant tank float switches, Allison converter housing reseal kits, CP3 inlet hoses and rear engine cover kits, and Mahle covers gaskets and seals such as the Y-bridge snout seal. BD Diesel brings turbo, manifold and Allison parts, Wehrli Custom Fabrication the fabricated intake pieces and sensors, Mishimoto Performance Parts the cooling parts, and MBRP compliant exhaust components, mufflers and resonators. For watching the truck there are Edge Products Insight monitors with EGT and pressure accessories. Oil and additives come from Hot Shot's Secret and Lucas Oil, Air Lift covers load control, Alliant Power and G&R Diesel cover injector and VGT pigtails and turbo drain plumbing, and Fleece Performance Engineering and XDP fill in engine-bay hardware, sensors and the service tools, including fuel filter adapter wrenches and flex plate bolt kits. Steering, transmission and Allison service listings fill in the rest.

Fitment notes

Order by engine code and body, not by year. The 2007 Classic is a GMT800 truck with an LBZ and shares nothing exterior with a 2007.5; intake and cold-side kits are sold LBZ versus LMM and classic versus new body for exactly that reason, and many engine parts are listed 2006-2010 or 2006-2016 across LBZ, LMM and LML, so read the engine code on the listing. Exhaust systems change with cab and box length, which runs from a 133 in wheelbase regular cab long box up to a 167 in crew cab long box. Fuel tanks differ too, 26 gal with the standard box and 34 gal with the long box, which matters for sump and draw-straw kits. The 3500HD came single or dual rear wheel, and brake rotor and caliper fitment splits 2500HD against 3500HD SRW and DRW, so verify by VIN. The 2010-to-2011 break is a hard wall: 2011 trucks got a new frame, control arms, torsion bars and leaf springs, a redesigned front differential, and both a different wheel offset, ET28 versus ET44, and a different bolt pattern, 8x165.1 versus 8x180, so 2011 and newer wheels, steering kits and suspension kits do not come back. On the hitch side, the B&W Turnoverball underbed gooseneck kit for these trucks is GNRK1067; GNRK1012 is the 2011-2015 HD kit and GNRK1057 is the 1500 kit. Built Allisons are 2WD or 4WD specific, up-pipe kits exclude the LGH van engine, and a CSF intercooler needs its outlet lip ground to clear 3.5 in cold-side pipes.

Frequently asked questions

Why does my Silverado go into regeneration so often?

Duty cycle first. Short trips, long idling and heavy towing interrupt regens before they finish, so the filter never fully cleans out and the ECM keeps asking for another one. Exhaust leaks are the second cause, because a leak upstream skews the DPF pressure and temperature sensors and triggers extra cycles. Before anyone quotes you a filter, let a full regen complete at highway speed, fix leaks, verify the sensors and run low-ash oil.

Does a 2007.5-2010 LMM need a lift pump?

The factory never fitted one. The CP3 draws fuel from the tank and pressurizes it, and it can have a hard time keeping up when the truck is loaded or tuned. A frame-mounted pump with extra water separation and filtration steadies supply and extends CP3 and injector life. Keep feed pressure modest, around 10 psi or less, and fix any air leak at the filter head or primer first, since that is what starves the pump to begin with.

How do I tell a sticking VGT from a worn-out turbo?

Sticking vanes give you boost that is strong down low with nothing on top, or the opposite, usually with P0299, P003A, P2563 or P0234 stored. Shaft play that lets the compressor wheel move toward the housing is a different problem and means rebuild or replacement, though a small amount of play is normal. Electrical faults in the actuator or the position-sensor wiring imitate stuck vanes exactly, so test those before condemning the unit. If it is only carbon, the turbine side comes apart and gets cleaned.

Can I add power and keep the truck emissions-legal?

Within limits, yes. The Edge Evolution CTS3, part 85400-200 with the 85401-201 California edition, is covered by CARB Executive Order D-802-13 for 2001-2016 Silverado and Sierra 2500 and 3500 6.6L Duramax trucks, and it functions only on emissions-equipped vehicles. Tune the Allison TCM along with the ECM or the transmission will limp, locked in third, in short order. Stay near 430 to 450 rwhp on a stock Allison and keep EGT in hand.

Will parts off a 2011 HD fit my 2010?

Often not. For 2011 GM replaced the frame, control arms, torsion bars and rear springs, changed the front differential design, and swapped the LMM for the LML with DEF and a CP4 pump. Wheels changed both offset and bolt pattern, and the 3 in downpipe sold for the 2011-2015.5 LML does not fit an LMM. Chassis, steering, suspension and exhaust parts for your truck stop at 2010, so shop the 2001-2010 and 2007.5-2010 listings.

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.