Reinforced cylinder head gasket BMW M54B22

The BMW engines covered

The BMW M54B22 is the 2.2-litre, 24-valve inline-six petrol engine fitted to the 320i and 320Ci (E46), the 520i (E39 and E60), the Z3 2.2i and the Z4 2.2i (E85) listed below.

This original gasket carries the part number 11 12 7 506 983, which replaces 11 12 1 435 586. It is a multi-layer steel (MLS) gasket with an 81 mm bore and a thickness of 0.70 mm; its repair size, 11 12 7 506 984, measures 1.00 mm, that is 0.30 mm more, and replaces 11 12 1 435 587. It is sized for standard combustion pressure: as that pressure rises, clamping load fades, the cylinder head lifts and coolant passes into a cylinder.

Reinforced cylinder head gaskets

The seal is not achieved by the gasket alone: it depends on the fasteners, which press the head against the block. Beyond 100 N/mm² of admissible stress, a composite gasket is crushed for good, whereas the 301 stainless steel of MLS gaskets withstands 517 N/mm², 5 times more, and regains its shape at every combustion.

This page brings together the part numbers of Cometic, an American maker of competition gaskets, in a single construction: the multi-layer steel MLS. Each gasket has an 81 mm bore, equal to that of the original gasket, and thicknesses range from 0.69 to 3.56 mm, enough to adjust the compression ratio without touching the pistons or the cylinder head. As a rule, the gasket bore chosen is at least 0.5 mm larger than the actual cylinder bore. Each part number is sold individually, one gasket per engine.

Technical specifications

Gasket volume is the free space left above each cylinder. It enlarges the combustion chamber, so a larger volume lowers the compression ratio. Compare these figures only between gaskets of the same bore.

Preparation and fitting

Before fitting, check with a straight edge the flatness of the cylinder head and of the block, and have them resurfaced if needed. No sealant is required: Cometic supplies these gaskets already coated.

Technical guide

The construction offered

Cometic MLS A stack of stamped stainless steel sheets fixed with rivets. The outer sheets have active beads around each cylinder and each fluid passage. A moderate clamping load is enough to seal, and the bore hardly distorts. It is the versatile solution, from the tuned naturally aspirated engine to moderate boost.

Choosing bore and thickness

Gasket bore. The Cometic MLS comes in 81 mm (C4351), and in that bore only.

Thickness. The original gasket is 0.70 mm thick, and 1.00 mm in the repair size (+0.30 mm). A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

When the chosen thickness is below the original, use a dial gauge to read how far the pistons stand proud of the block: it sets the clearance left between piston and head.

The brand

Founded in 1989 in Concord, Ohio, Cometic Gasket, Inc. is an American company that designs gaskets and sealing solutions for engines. Its reputation comes from the gasket made to order, in the bore and thickness wanted. All of its production stays in the United States, with American materials.

Advantages over the original gasket

When a reinforced gasket becomes necessary

• Adding forced induction, or raising boost on an already turbocharged engine
• Cylinder rebored beyond what the 81 mm bore of the original gasket covers
• Looking for a compression ratio different from standard, higher or lower
• Engine that has already lost its gasket, or is consuming coolant
• Competition use, where the gasket goes through repeated temperature rises

Vehicle compatibility

OEM part number: 11 12 7 506 983, repair size 11 12 7 506 984.

Important: the part numbers on this page fit the M54B22 engine only: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

As soon as the original gasket reaches its limit, the reinforced gasket keeps working: when combustion pressure climbs, it stays in shape instead of being crushed.

When power goes up, through a supercharger, a turbo or a raised compression ratio, the head gasket is the first part to give way in the top end. Choosing a reinforced gasket therefore means putting reliability ahead of comfort: it avoids the breakdown, and the cylinder head removal that follows.