Reinforced head gasket Opel Vauxhall 2.0 16V 20XE C20XE C20LET Z20LET

The Opel engines covered

Opel's 2.0 litre inline four with 16 valves and twin overhead camshafts comes as the naturally aspirated 20XE and C20XE and the turbocharged C20LET and Z20LET. It powers the Opel Kadett E, Astra F and G, Vectra A, Calibra, Zafira A OPC and Speedster, and their Vauxhall cousins the Astra, Cavalier, Calibra, Zafira and VX220 in the table below. A single head covers the four cylinders: the gasket is sold individually, one per engine.

The manufacturer part number of the standard gasket is 6 07 442; neither its bore, nor its thickness, nor its construction appears in any published documentation. It is sized for the original combustion pressure: beyond it, the clamping load loses its grip, the head lifts and coolant passes into a cylinder.

Reinforced cylinder head gaskets

The seal does not come from the gasket alone: the fasteners that pull the head onto the block contribute just as much. A composite gasket settles permanently beyond 100 N/mm², whereas the 301 stainless steel of the MLS carries 517 N/mm², 5 times more, and springs back with every combustion. The raised beads of the outer sheets focus the clamping load around each cylinder and each fluid passage, with no machining of the block.

This page gathers the part numbers of a single racing manufacturer, Cometic, in two constructions: the multi-layer MLS and the MLX with a chamber stopper, with two gasket bores, 86.5 and 88 mm. Thicknesses run from 0.686 to 3.556 mm, enough to adjust the compression ratio without altering either the pistons or the 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

A gasket's volume is the open space it leaves above each cylinder. It adds to the combustion chamber and lowers the compression ratio by the same amount. Compare these values only between gaskets of the same bore.

Preparation and fitting

At assembly, first check the flatness of the head and the block with a straight edge, then have whichever needs it resurfaced. Use no sealing paste: Cometic delivers its gaskets already coated.

Technical guide

The two constructions offered

	Cometic MLS Stainless steel sheets, stamped, stacked and then riveted. The outer sheets carry active beads around each cylinder and each coolant passage. A measured clamping load is enough to seal, and the bore distorts little. An all-round solution, from the tuned naturally aspirated engine to reasonable boost.
	MLX Cometic Embossed, riveted stainless steel sheets, including a folded centre sheet that forms a stopper around the combustion chamber, all under a high-temperature coating. The clamping load rises locally without distorting the bore any further. It is the toughest of the all-steel gaskets, for high boost pressures; here it comes in 88 mm, in a single thickness (1.27 mm).

Choosing bore and thickness

Gasket bore. The Cometic MLS comes in 88 mm (C4216, H2795 and H1184) and 86.5 mm (H1184SP8120S); the Cometic MLX comes in 88 mm (C4960).

Thickness. The manufacturer publishes no thickness for the standard gasket: only the measurement of the gasket you take off counts. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

As the original thickness is not published, use a dial gauge to read how far the pistons stand proud of the block deck: it tells you the clearance left between piston and head, especially with the thinnest gasket.

The brand

Founded in 1989 in Concord, Ohio, Cometic Gasket, Inc. makes engine gaskets and sealing solutions. It specialises in the made-to-measure gasket, cut to the bore and thickness required and produced entirely in the United States from 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 bore of the gaskets offered (86.5 and 88 mm) 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: 6 07 442.

Important: the gaskets on this page are listed for the 2.0 litre 16-valve 20XE, C20XE, C20LET and Z20LET engines in the survey below, at Opel and Vauxhall. For any other vehicle, find the engine code first before placing an order.

Why switch to a reinforced gasket?

When the standard gasket is at the end of its life, the reinforced gasket steps in: under higher combustion pressure it holds its shape instead of being crushed.

Once an engine sees higher boost, higher compression or a serious build, the head gasket is the first part of the top end to fail. A reinforced gasket spares you the leak and the head removal that follows, a job far more expensive than the part itself.