Duramax 01-16 Left Side Cylinder Head Gasket 5458X (Grade C 1.05 Thickness) – MAHLE 55027

Restore a reliable seal between the cylinder head and block on your 2001-2016 GM 6.6L Duramax with this MAHLE Original left-side (driver-side) cylinder head gasket. The 55027 is the current Grade C replacement (superseding the older 54585) and is engineered specifically for the demanding conditions of the LB7, LLY, LBZ, LMM, and LML engines.

This multi-layered steel (MLS) gasket incorporates MAHLE’s Combustion Load Limiter (Wave-Stopper) technology. The design allows the gasket to adapt to the fluctuating combustion pressures and thermal loads typical of a Duramax, helping maintain a consistent seal and reducing the risk of leaks or blowouts under normal or moderate performance use.

Key Features

• Multi-layered steel construction with Combustion Load Limiter technology
• Grade C thickness of 1.05 mm — the most common service replacement thickness
• Direct-fit replacement for standard-bore cylinders
• Torque-to-yield compatible design for consistent clamping force
• Stamped for left/driver-side identification
• Quality-tested OE-style gasket

Fitment

• 2001–2016 GM 6.6L Duramax (LB7 / LLY / LBZ / LMM / LML)
• Left (driver) side only

Important Notes

• Sold individually (right-side gasket is MAHLE 55026 / previously 54582)
• For standard bore cylinders only
• Cylinder head bolts or studs are not included
• Confirm required gasket thickness with your engine builder based on piston protrusion and any machining performed

This is a high-quality, OE-level replacement gasket designed to deliver a durable, long-lasting seal when installed correctly.