Reinforced head gasket Mercedes M104 2.8 3.0 3.2 W124 W140 R129

The Mercedes-Benz engines covered

The M104 petrol engines of 2.8, 3.0 and 3.2 litres, inline sixes with twenty-four valves, power the Mercedes-Benz C-Class (W202), E-Class (W124 and W210), S-Class (W140), SL (R129) and G-Class (W463) in the compatibility table below. Each takes a single cylinder head gasket.

Two original gaskets are listed: 104 016 17 20 for the M104 engines of 2.8 and 3.2 litres, and 104 016 16 20 for the M104 engines of 3.0 litres. Mercedes-Benz publishes neither the bore, nor the thickness, nor the construction of these gaskets. They are calculated for the standard combustion pressure: when it rises, the clamping load fades, the cylinder head lifts off the block and coolant finds its way into a cylinder.

Reinforced cylinder head gaskets

The fasteners that clamp the head onto the block provide half of the sealing: the gasket cannot do everything. Above 100 N/mm², a composite gasket settles for good; the 301 stainless steel of MLS gaskets withstands up to 517 N/mm², 5 times more, and recovers its shape at every combustion.

This page presents two Cometic part numbers, an American maker of competition gaskets, in a single construction: MLS. The bore is 91 mm, with two thicknesses, 1.78 and 2.03 mm. By convention, the gasket bore exceeds the cylinder bore by at least 0.5 mm. Each part number is sold individually: the engine is an inline six that takes a single gasket.

Technical specifications

Gasket volume is the space it leaves open above each cylinder. It adds to the combustion chamber and lowers the compression ratio; as both part numbers share the same bore, the thicker one, 2.03 mm, lowers it the most.

Preparation and fitting

Before fitting, check with a straight edge that the head and block faces are flat, and have them resurfaced if needed. Cometic supplies the gasket already coated: apply no sealing paste.

Technical guide

The construction offered

Cometic MLS Several embossed stainless steel sheets, stacked and then riveted. The outer sheets carry active beads around each cylinder and each fluid passage. Moderate clamping is enough to seal, and the bore distorts little. A versatile gasket, from the tuned naturally aspirated engine to moderate forced induction.

Choosing bore and thickness

Gasket bore. The Cometic MLS gasket comes here only in 91 mm (H3637070S and H3637080S).

Thickness. Mercedes-Benz publishes no thickness for the original gaskets. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

With no published original thickness, use a dial gauge to measure how far the pistons stand proud of the block deck, particularly if you choose 1.78 mm: it shows the clearance left between piston and head.

The brand

Cometic Gasket, Inc., founded in 1989 in Concord, Ohio, is an American maker of engine gaskets and sealing solutions. Its reputation rests on the made-to-measure gasket, cut to the bore and thickness requested, and on production carried out entirely in the United States from local raw 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 91 mm bore of the gasket offered 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: 104 016 17 20 and 104 016 16 20.

Important: the part numbers on this page fit only the M104 engines of 2.8, 3.0 and 3.2 litres in the compatibility table: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches the end of its capacity, the reinforced gasket takes over: under a higher combustion pressure it does not crush and keeps its geometry.

Turbo, supercharger or a raised compression ratio on an M104 six: the head gasket is the first weak link of the top end. A reinforced gasket avoids the leak and the head removal that follows, a job far dearer than the part.