Reinforced cylinder head gasket Opel Chevrolet 2.2 16V Z22SE L61

The Opel, Chevrolet, Oldsmobile, Pontiac and Saturn engines covered

The 2.2-litre 16-valve petrol engines Z22SE and L61 are fitted to the Opel, Chevrolet, Oldsmobile, Pontiac and Saturn models listed below.

The original gasket of these engines carries the part numbers 56 07 474, 93 170 143 and 24444091. Its bore is 87.3 mm; Opel publishes neither the construction nor the thickness. It is sized for standard pressure: as soon as that rises, clamping weakens, the cylinder head lifts and coolant passes into a cylinder.

Reinforced cylinder head gaskets

The head gasket does not seal on its own: the fasteners that pull the head down onto the block matter just as much. Beyond 100 N/mm², a composite gasket settles for good; the 301 stainless steel of MLS gaskets withstands 517 N/mm², 5 times more, and returns to shape at every combustion.

This page lists the part numbers of Cometic, an American maker of competition gaskets, in one construction only: the multi-layer steel MLS. All the gaskets have an 87 mm bore and thicknesses 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 space left above each cylinder. It adds to the combustion chamber and lowers the compression ratio, the more so as it grows. Compare these values only between gaskets of the same bore.

Preparation and fitting

Before fitting, check with a straight edge that the head and block faces are flat, and have them machined if necessary. Do not apply sealing paste: Cometic gaskets arrive already coated.

Technical guide

The construction offered

MLS Cometic Stainless steel layers, stamped and joined by rivets. The outer layers carry active beads around each cylinder and each fluid passage. A moderate tightening torque is enough to seal and the bore distorts very little. This all-round solution runs from the prepared naturally aspirated engine to moderate boost.

Choosing bore and thickness

Gasket bore. The Cometic MLS is offered in 87 mm (C5768), in that bore alone.

Thickness. The thickness of the original gasket is absent from Opel's documentation. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

If you choose a thickness below the original, measure with a dial gauge how far the pistons stand proud of the block deck: it sets the clearance left between piston and head.

The brand

Cometic Gasket, Inc. is an American manufacturer of engine gaskets and sealing solutions, founded in 1989 in Concord, Ohio. Its speciality is the made-to-measure gasket, cut to the required bore and thickness. All of its production remains 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 87.3 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: 56 07 474, 93 170 143 and 24444091.

Important: the part numbers on this page fit only the Z22SE and L61 engines: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches its limits, the reinforced gasket takes over: at higher combustion pressure it holds its shape and does not crush.

With a turbo, a supercharger or a higher compression ratio, the head gasket is the first part to be loaded: it is the most stressed component of the top end. A reinforced gasket avoids the leak and the head removal that follows.