Reinforced head gasket Ford Mondeo III Maverick Mazda 6 3.0 V6 AJ MEBA REBA

The Ford and Mazda engines covered

The AJ, MEBA and REBA petrol engines are 2,967 cm³ (3.0 litre) 24-valve V6 units. They are fitted to the Ford Mondeo III, Maverick and Escape, the Mazda 6, MPV II and Tribute, and the Morgan Roadster, all listed below.

The original gasket of these engines carries part numbers 4 921 510 and 4 832 568, depending on the version. The manufacturer publishes neither its bore, nor its construction, nor its thickness. It is rated for stock combustion pressure: when that climbs, the clamping force eases, the head lifts and coolant finds its way into a cylinder.

Reinforced cylinder head gaskets

The head gasket does not seal alone: sealing also depends on the fasteners that pull each head down onto the block. The O-Ring divides the roles: its stainless ring seals the combustion chamber by itself, the gasket body looks after the water and oil passages, and no groove has to be machined in the block.

This page lists two Athena part numbers, from an Italian maker of competition gaskets, both in the same construction: the O-Ring, a steel sheet faced with aramid fibre and ringed with a stainless steel ring. Each has a 97.6 mm bore and a 1.00 mm thickness. As the engine is a V6, two gaskets are needed: 330031R fits the right cylinder bank and 330032R the left bank. 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 cylinder head.

Technical specifications

Gasket volume is the space the gasket leaves free above each cylinder. It adds to the combustion chamber and lowers the compression ratio; two gaskets can only be compared at the same bore.

Preparation and fitting

Before fitting, run a straight edge over the head and the block to check flatness, then have them resurfaced if needed. Athena supplies this gasket already coated: do not add sealing paste.

Technical guide

The construction offered

Athena O-Ring A steel sheet dressed with asbestos-free aramid fibre, surrounding each cylinder with a stainless steel compression ring. The ring transfers the clamping force onto a narrow band, where the seal is made, and a silicone bead protects the water and oil passages. It is the construction that withstands the highest pressures in the range.

Choosing bore and thickness

Gasket bore. The Athena O-Ring comes in 97.6 mm: 330031R for the right bank, 330032R for the left bank.

Thickness. No thickness figure for the original gasket is released by the manufacturer. 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 check how far the pistons protrude above the block deck, particularly if the removed gasket is thinner than 1.00 mm: this gives the clearance left between piston and head.

The brand

Athena S.p.A. is an Italian group making gaskets and engine parts, with its head office and main plant in Alonte, in the Veneto. It also has sites in Spain, the United States, Brazil and India. Its multi-layer gaskets are fitted by car makers as original equipment, and its competition range is designed and made entirely 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 97.6 mm bore shared by both 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: 4 921 510 and 4 832 568.

Important: the part numbers on this page only suit the AJ, MEBA and REBA engines: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

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

When power is raised, through a turbo, a supercharger or a higher compression ratio, the head gasket becomes the weak link of this V6, the first part to give way under the extra load. A reinforced gasket prevents the leak, and with it the removal of the head concerned and the work that goes with it.