The head gaskets on the 2006–2007 6.6L Duramax LBZ seal the cylinder heads to the engine block. They handle the high pressure and heat of diesel combustion. These multi-layer steel (MLS) gaskets use stacked steel layers with a rubber-like coating. This helps seal oil and coolant passages while keeping compression tight.

LBZ gaskets are tough but can fail over time. Overheating, high boost, or poor installation are common causes. The engine uses different gasket thicknesses based on piston height, so measuring correctly is important during a rebuild.

With proper install, torque specs, and new bolts or studs, these gaskets seal well. They can handle the LBZ’s stock torque and hold up under tuning.