Reinforced cylinder head gasket Mitsubishi 6G72 6G72-T 3000GT GTO Dodge Stealth

The Mitsubishi engines covered

The 6G72 DOHC 24-valve and the 6G72-T are the petrol V6 engines of 3.0 litres (2972 cc) of the Mitsubishi 3000 GT, GTO, Diamante, Sigma, Debonair, Grandis and Space Wagon, the Dodge Stealth and the Hyundai Grandeur in the table below; the 6G72-T is the turbocharged version.

For the 6G72, the original gasket carries part number MD320044; Mitsubishi publishes neither its bore, nor its construction, nor its thickness. For the 6G72-T, no original part number is confirmed. A standard gasket is sized for the standard combustion pressure: once that rises, the clamping load weakens, the head lifts and coolant reaches a cylinder.

Reinforced cylinder head gaskets

A gasket does not seal alone: the bolts or studs that clamp the head onto the block play an equal part. With the O-Ring the roles are shared: the stainless ring closes off the combustion chamber, the gasket body channels water and oil, and no machining of the block is needed.

This page presents two part numbers from Athena, an Italian maker of competition gaskets, in a single construction: the O-Ring, a steel sheet faced with aramid fibre and ringed with stainless steel. The 330071R has a bore of 93.5 mm, the 330098R of 95 mm; the thickness is 1.20 mm for both. Each part number is sold individually.

Technical specifications

A gasket's volume is the void it leaves above each piston: it enlarges the combustion chamber and so lowers the compression ratio. Only two gaskets of the same bore can be compared on this basis.

Preparation and fitting

Check the flatness of the head and block with a straightedge before fitting the gasket, and have any warped face resurfaced. Athena supplies this gasket already coated: no sealing paste needs to be added.

Technical guide

The construction offered

Athena O-Ring A steel body dressed in asbestos-free aramid fibre, with each cylinder circled by a stainless steel ring. The ring concentrates the clamping load on a narrow band, where sealing is won or lost, and a silicone bead closes the water and oil passages. The coating is applied at the factory. It is the construction that withstands the highest combustion pressures in the range.

Choosing bore and thickness

Gasket bore. The Athena O-Ring comes in 93.5 mm (330071R) and 95 mm (330098R), with no other bore.

Thickness. Mitsubishi does not publish the thickness of the original gasket: only the dimension taken on the removed gasket is a valid reference. 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, measure with a dial gauge how far the pistons protrude above the block's gasket face, especially if the removed gasket is thinner than 1.20 mm: this figure gives the clearance left between piston and head.

The brand

Athena S.p.A. is an Italian group making gaskets and engine parts, whose main plant is in Alonte, in the Veneto. Further sites exist in Spain, the United States, Brazil and India. Its multilayer gaskets are fitted by car makers as original equipment, and the whole competition range is designed and built in Italy.

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 (93.5 to 95 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: MD320044 for the 6G72.

Important: the part numbers on this page are listed for the 6G72 DOHC 24-valve and 6G72-T engines in the table below: read your vehicle's engine code before ordering, then choose the bore you need.

Why switch to a reinforced gasket?

When the original gasket reaches its limit, the reinforced gasket takes over: it keeps its shape under higher combustion pressure instead of crushing.

As soon as an engine is modified, with a raised compression ratio or added forced induction such as a turbo or a supercharger, the head gasket is the part that fails first on this V6. A reinforced gasket rules out the leak and the head removal that results, together with the matching workshop hours.