Reinforced head gasket Volkswagen Audi 1.8 20V Golf IV Passat A4 A6

The Volkswagen and Audi engines covered

The 1.8-litre twenty-valve petrol engines, inline fours with five valves per cylinder, are found in the Volkswagen Passat B5, Bora and Golf IV, as well as the Audi A3 (8L1), A4 B5, A6 C4, A6 C5 and Cabriolet in the compatibility table below. Each takes a single cylinder head gasket.

Two original gaskets are listed: 058 103 383 H for the ADR, AFY, AGN, APG, APT, ARG and AVV engines, then 06B 103 383 B for the AQE, ARH and AJP. The manufacturer states neither the bore, nor the construction, nor the thickness. They are designed for the standard combustion pressure: if it climbs, the clamping load shrinks, the head lifts off the block and coolant reaches a cylinder.

Reinforced cylinder head gaskets

The bolts or studs that clamp the head onto the block supply half of the sealing: the gasket does not do it all. Above 100 N/mm², a composite gasket settles for good; the 301 stainless steel of MLS gaskets holds up to 517 N/mm², 5 times more, and springs back at every combustion.

This page gathers three Cometic part numbers, an American maker of competition gaskets, in a single construction: MLS. Two bores are offered, 83 mm (thicknesses 1.02 and 1.30 mm) and 85 mm (thickness 1.30 mm). By convention, the gasket bore exceeds the cylinder bore by at least 0.5 mm. Each part number is sold individually: this inline four takes just one gasket.

Technical specifications

Gasket volume is the space it provides above each cylinder. Added to the combustion chamber, it lowers the compression ratio; at equal bore, the 1.30 mm thickness lowers it the most.

Preparation and fitting

Before fitting, press a straight edge across the head and the block to check they are flat, then have them resurfaced if needed. Cometic supplies the gasket already coated: apply no sealing paste.

Technical guide

The construction offered

Cometic MLS Embossed stainless steel sheets, laid over one another and then riveted. The outer sheets carry active beads around every cylinder and every fluid duct. Moderate clamping is enough to seal and the bore moves little. A versatile gasket, from the tuned naturally aspirated engine to moderate forced induction.

Choosing bore and thickness

Gasket bore. The Cometic MLS gasket is offered in 83 mm (H3078SP6040S and H3078SP6051S) and in 85 mm (H3078SP2051S).

Thickness. The manufacturer 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.

Without a published original thickness, use a dial gauge to read how far the pistons stand proud of the block face, especially if you pick 1.02 mm: the reading gives the clearance left between piston and head.

The brand

Based in Concord, Ohio since 1989, Cometic Gasket, Inc. designs engine gaskets and sealing parts. Its know-how is the made-to-measure gasket, cut to the bore and thickness requested and produced 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 83 mm and 85 mm bores of the gaskets 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: 058 103 383 H and 06B 103 383 B.

Important: the part numbers on this page fit only the engines in the compatibility table: read off your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

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

Add a turbo, a supercharger or a raised compression ratio to this inline four and the head gasket becomes the first link to give way. A reinforced gasket spares the leak, then the head removal, which costs far more than the part.