Reinforced head gasket Mitsubishi 2.4 4G64

The Mitsubishi engines covered

The 4G64 petrol engine of 2.4 litres, a four-cylinder, powers many pick-ups, SUVs and MPVs from Mitsubishi, Dodge, Plymouth, Hyundai, Fiat and other makes, detailed below.

The original gasket carries part number MD068823. Mitsubishi publishes neither its bore, nor its thickness, nor its construction. Calculated for the standard combustion pressure, it no longer keeps up when that climbs: the clamping force drops, the cylinder head lifts slightly off the block and coolant leaks into a cylinder.

Reinforced cylinder head gaskets

The gasket does not seal on its own: it also depends on the fasteners that clamp the cylinder head onto the block. Copper at 99.9% resists corrosion, deforms without breaking and carries heat away well, with no brittleness at high temperature.

This page covers the two part numbers of the American maker Cometic, a specialist in competition gaskets, in a single construction: copper. Both have an 88 mm bore; the thickness is 1.27 mm or 1.60 mm. The gasket is designed slightly wider than the cylinder, by at least 0.5 mm on the bore. Each part number is sold individually, one gasket per engine.

Technical specifications

A gasket's volume is the space it keeps free above each cylinder. That space joins the combustion chamber and lowers the compression ratio; only gaskets of the same bore are compared.

Preparation and fitting

Before fitting, run a straight edge over the cylinder head and block to check they are flat, and have them resurfaced if needed. Cometic checks the flatness of each copper gasket it makes.

Technical guide

The construction offered

Choosing bore and thickness

Gasket bore. The Cometic copper gaskets come in 88 mm (C4213-050 and C4213-063), with no other bore.

Thickness. Mitsubishi gives no thickness for the original gasket. 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 above the block face, especially if you are aiming for the 1.27 mm thickness: this reading shows the clearance that remains between piston and cylinder head.

The brand

Cometic Gasket, Inc. is an American maker of gaskets and sealing parts for engines, born in 1989 in Concord, Ohio. It made a name with the custom gasket, cut to the bore and thickness wanted, made entirely in the United States from American 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 88 mm bore 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: MD068823.

Important: the part numbers on this page suit the 4G64 engine: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches its ceiling, this copper gasket takes over: pure copper stays ductile when hot and does not turn brittle, which preserves the seal between head and block.

With a turbo, a supercharger or a raised compression ratio, the head gasket becomes the first breaking point of the top end. A reinforced gasket rules out the leak and the cylinder head removal that follows, a job far costlier than the gasket.