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Head Gasket Kit, LLY LBZ LMM Duramax | 2004.5-2010

Merchant Automotive

$299.63 - $1,299.92
SKU:
4505
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This head gasket kit covers all three Duramax engines from 2004.5 to 2010: the LLY, LBZ and LMM in Chevy Silverado and GMC Sierra 2500HD and 3500HD trucks. Each engine uses a slightly different set of intake, EGR and injector seals, so we pack the seals for all three in one box. You'll use the ones that match your engine and have a few left over.

The kit has the gaskets and seals for the parts that come off to get the heads out: valve covers, exhaust manifolds, up pipes, turbo lines, EGR tubes, the intake and the injectors. You choose the head gaskets and head bolts when you order.

Kit Options

What's Included

Every version of the kit has these parts, grouped by the engine they're used on:

All three engines

LLY only (2004.5-2005)

LLY and LBZ (2004.5-2007)

LBZ and LMM (2006-2010)

LMM only (2007.5-2010)

Signs of a Blown Head Gasket

  • White smoke from the tailpipe
  • Coolant loss with no leak you can find
  • Milky looking engine oil
  • Overheating
  • Bubbles in the radiator or coolant reservoir
  • Coolant pushing out of the reservoir, or a hard upper radiator hose before the engine is started
  • Coolant streaks near the head gasket

Before You Order

  • This kit fits the LLY, LBZ and LMM. For an LB7, LML or L5P, see our other head gasket kits.
  • Grade C is the only head gasket grade offered with this kit. If your engine needs a different grade, order the kit without head gaskets.
  • Coolant, oil and filters aren't included.

Frequently Asked Questions

Why will I have parts left over?
The kit is built to cover the LLY, LBZ and LMM. Some seals are only used on one or two of those engines, so a few will be left when you're done. The What's Included list above shows which engine each part is for.

Should I get the OEM head bolts or the ARP studs?
Either one works. The factory head bolts are torque to yield, so whichever way you go, the old ones shouldn't be reused. New OEM bolts are the lower cost choice. ARP studs clamp harder and are a common pick on tuned trucks, but they aren't required to fix a blown head gasket. If you use studs, follow ARP's torque steps and recheck them before the engine goes back together.

What does Grade C mean?
GM makes Duramax head gaskets in different thicknesses, called grades. The grade an engine needs depends on how far the pistons stick up out of the block. If you don't know which grade yours needs, check before ordering.

Are the head gaskets different for each side?
Yes. The left (driver) and right (passenger) gaskets aren't interchangeable, and each one is marked. Installing one on the wrong side is a common mistake, so check the marking before the head goes on.

Should the heads go to a machine shop?
In most cases, yes. Have the heads checked for cracks and flatness, and check the block deck with a straightedge while it's open.

Do I need to pull the cab?
Both ways are done. Many shops pull the cab when they have a lift because it opens up the back of the engine. With the cab on, the job is tighter, especially at the firewall.

What else should I replace while the heads are off?
The water pump, thermostats, glow plugs and old coolant hoses are the parts people most often replace at the same time. See our water pump kits for 2001-2005 and 2006-2016, the thermostat kit, and glow plug kits for the LLY and LBZ and LMM.

Can I order the kit without head gaskets?
Yes. Pick "none" for head gaskets and you'll get everything else in the kit.

Are the injectors included?
No. The kit has new copper washers and body seals for all eight injectors, but not the injectors.

For warranty information, see our Warranty Policy.

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