MAHLE 55523 L5P Duramax Cylinder Head Gasket (Grade B)

Restore factory-tight combustion sealing and eliminate head gasket leaks on your 2017–2023 GM 6.6L Duramax L5P with this premium MAHLE 55523 Grade B multi-layer steel (MLS) cylinder head gasket. Designed as a direct-fit OE-grade replacement, it delivers reliable, long-lasting performance for stock, work, tow, and mild-performance builds.

Key Features & Benefits

• Grade B Thickness — 1.19–1.31 mm (approx. 0.047"–0.052") service thickness, ideal for engines with minor head or block resurfacing.
• Multi-Layer Steel (MLS) Construction — Provides exceptional strength, heat resistance, and durability under high cylinder pressures.
• Combustion Load Limiter — Helps maintain consistent clamp load and protects the gasket from excessive pressure.
• Torque-to-Yield (TTY) Compatible — Engineered for use with torque-to-yield head bolts to achieve and maintain optimal sealing.
• OE Form, Fit & Function — Manufactured by MAHLE, a trusted global supplier of engine components, ensuring precise port alignment and fire-ring geometry for the L5P.

Specifications

• Part Number: MAHLE 55523
• Material: Multi-Layer Steel (MLS) with combustion load limiter
• Thickness (Grade B): 1.19 mm – 1.31 mm
• Sold Individually — 2 required per engine (one per cylinder bank; left and right are identical on L5P)

Vehicle Fitment

• 2017–2023 Chevrolet Silverado 2500HD / 3500HD – 6.6L Duramax L5P (VIN Y)
• 2017–2023 GMC Sierra 2500HD / 3500HD – 6.6L Duramax L5P (VIN Y)

Note: Confirm exact fitment by measuring piston protrusion. Grade selection is critical.

Important Installation Notes

Grade B is selected based on piston protrusion measurements at Top Dead Center (TDC):

• Grade A: ~0.016"–0.021" protrusion (thinner)
• Grade B: ~0.021"–0.023" protrusion (this gasket)
• Grade C: ~0.023"–0.029" protrusion (thicker)

Always measure piston protrusion before ordering to avoid piston-to-head or valve contact issues. Clean, flat deck and head surfaces with proper surface finish are essential for MLS gasket sealing. Use new torque-to-yield head bolts (or upgraded head studs) and follow the correct torque/angle sequence. Professional installation is strongly recommended.

This MAHLE Grade B head gasket offers a dependable, high-quality solution for restoring compression, preventing coolant/oil leaks, and getting your L5P Duramax back on the road with confidence.