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Call or Text (352) 722-5295Starting a 2007.5-2010 GMC Sierra HD LMM
The starter on a 6.6L Duramax Sierra HD pulls from two batteries wired in parallel. GMC specified a heavy-duty 730-CCA battery with rundown protection for the diesel, and the smaller 600-CCA auxiliary battery from the gas-truck options was not available. On cold starts the LMM uses fast-heating glow plugs managed by a glow plug control module. Batteries, glow system and starter all have to do their part, so a hard start on a Sierra isn't automatically a starter problem.
Diagnose first, then replace
Starters aren't a documented LMM trouble spot, so make the starter the last suspect, not the first. This is the order that makes sense on a Sierra HD:
- Batteries. Weak batteries make winter hard starts worse. Load-test both, since one failing battery can pull down its partner.
- Parasitic draw. Some owners find a key-off drain that flattens the batteries overnight; one measured 2.6 amps.
- Glow system. A normal-speed crank with no fire on a cold morning points away from the starter. Glow plug control module faults can mimic bad plugs.
- Starter circuit. Once the batteries and glow system check out and cranking is still the problem, replace the starter or its solenoid.
Stock replacement vs. upgrade
Every starter in this collection is an aftermarket gear-reduction unit for the 6.6L Duramax rather than a GM service part. The choice comes down to brand, finish and availability. If you want to keep your starter and swap only the solenoid, that option is here as well, along with new bolts so the install doesn't depend on corroded original hardware.
What we carry
From XDP, the XD251 HD gear-reduction starter in wrinkle black, listed for 2001-2019 6.6L Duramax, and the XD533 black-phosphate starter bolt kit for 2001-2022 engines. From Mean Green, the 6600 gear-reduction starter for 2001-2019 6.6L Duramax. From Merchant Automotive, the 10460 starter solenoid for 2001-2016 6.6L Duramax.
Fitment notes
The LMM went into the mid-2007 through 2010 GMT900 Sierra 2500HD and 3500HD, in WT, SLE and SLT trim, with single or dual rear wheels. The Denali HD came later, for 2011. If your truck is a 2007 Sierra Classic, it has the older body and the LBZ. The parts here list wider year ranges than the LMM, so verify by VIN or use the fitment checker before ordering.
Frequently asked questions
Will a new starter cure a hard start in winter?
Not if the batteries or glow system are the cause. On the LMM, weak batteries make winter hard starts worse, and glow plug control module faults can look like bad plugs. Load-test both batteries and check the glow system before you replace the starter.
What is the difference between the XDP and Mean Green starters?
Both are gear-reduction starters listed for 2001-2019 6.6L Duramax engines, so either covers the LMM Sierra. The XDP XD251 HD comes in a wrinkle black finish. Compare the details on each product page, or call and we will help you choose.
Is the XD533 bolt kit only for the LMM?
No. XDP lists it for 6.6L Duramax engines from 2001 through 2022, which takes in the LMM years. It is black-phosphate hardware, a sensible add when your original bolts are corroded.
Do these starters fit a Savana van or TopKick with the LMM?
This page is built for Sierra HD pickups. The Savana van and the TopKick medium-duty truck also used the LMM, but on a different chassis, so confirm by VIN before ordering a starter for one of them.
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 at our shop in Wildwood, FL.