Reinforced head gasket Ford Mazda 2.0 2.3 16V Duratec LF-DE

The Ford and Mazda engines covered

The Ford Duratec and Mazda MZR petrol engines of 2.0 and 2.3 litres, codes AODA, AODB, AODE, SYDA, AOBA, AOBC, TBBA, TBBB, AOWA, AOWB, TBWA, TBWB, T23HDEX, CJBA, CJBB, N4JB, GZ, B4204S3, B4204S4, L3-VE, SEBA, SEWA, C23HDEX, LF-DE, LF18, LF-VE, LF-ZB, LF17, LF4J, LF4K, LF50, LF5H, LF5W, LF72, LFG7, LFG8, LFN7, LFN8, LFY7, LFYA, LFYB and LFZD, are fitted to the Ford Focus, C-MAX, Mondeo, Galaxy, S-MAX, Fusion and Ranger and to the Mazda 3, 5, 6, MX-5, MPV, Premacy and Tribute, the Ford Fiesta and Maverick and the Volvo C30, S40, S80, V50 and V70 detailed below.

The original gasket carries the part numbers 1 124 372, 1 129 043, 1 229 872, 1S7G 6051AJ and 30 777 325 on the engines AODA, AODB, AODE, SYDA, AOBA, AOBC, TBBA, TBBB, AOWA, AOWB, TBWA, TBWB, T23HDEX, CJBA, CJBB, N4JB, GZ, B4204S3, B4204S4 and L3-VE, and L3G2-10-271A and L309-10-271 on the SEBA, SEWA, C23HDEX, LF-DE, LF18, LF-VE, LF17, LF4J, LF4K, LF50, LF5H, LF5W, LF72, LFG7, LFG8, LFN7, LFN8, LFY7, LFYA, LFYB and LFZD. The LF-ZB carries the part number LF3F-10-271. Ford and Mazda publish neither its bore, nor its thickness, nor its construction. It is sized for the standard pressure: when pressure rises, the clamping load drops, the head lifts and coolant reaches a cylinder.

Reinforced cylinder head gaskets

The head gasket does not seal alone: the fasteners that clamp the head to the block contribute just as much. A composite gasket is permanently crushed beyond 100 N/mm²; the 301 stainless steel of MLS gaskets withstands 517, 5 times more, and regains its shape on every combustion.

This page gathers the part numbers of Cometic, an American maker of competition gaskets, and of Athena, an Italian maker, in a single construction: MLS, multilayer steel. The gaskets come in bores of 89, 89.5, 90, 91 and 92 mm, and in thicknesses from 0.46 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 free space the gasket leaves above each cylinder. It adds to the combustion chamber and lowers the compression ratio, more so the larger it is. Only compare these figures 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 sealant: Cometic and Athena gaskets are supplied already coated.

Technical guide

The three constructions offered

	Athena O-Ring / Cut Ring A steel blank dressed with asbestos-free aramid, on which a stainless compression ring is crimped around each combustion chamber. The ring transfers the clamping load to a thin sealing band, which strengthens the combustion seal, and a silicone bead closes the water and oil channels. Among the constructions offered here, it is the one that copes best with very high cylinder pressures.
	Athena MLS From two to five layers of AISI 301 stainless steel, laser cut, embossed and riveted together. Around each cylinder, a sheet folded back on itself, the Gas Stopper, carries the clamping force over to the combustion chamber, while beads keep the water and oil circuits apart. The outer faces are coated: a first layer resists heat and fills small flaws in the block and head, a silicone layer keeps the gasket from sticking when it is removed. It is Athena's all-steel construction, for the prepared naturally aspirated engine as well as moderate boost.
	Cometic MLS Several stainless steel layers, stamped and joined by rivets. The outer layers carry active beads around each cylinder and each fluid passage. A moderate clamping load is enough to seal and the bore deforms little. A versatile construction, from the tuned naturally aspirated engine to moderate boost.

Choosing bore and thickness

Gasket bore. The Cometic MLS is offered in 89.5 mm (C5843) and in 92 mm (C5842). It also comes in 90 mm (H2389). The Athena MLS comes in 89 mm (338469R, 338471R, 338477R, 338509R, 338510R, 338511R), in 90 mm (338478R) and in 91 mm (338470R, 338472R). Athena also offers two 89 mm O-Rings: 330056R in 1.20 mm and 330152R in 1.30 mm.

Thickness. Ford and Mazda publish no thickness for the original gasket of these engines. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

Before choosing a thickness below the original, use a dial gauge to read how far the pistons stand proud of the block face: that figure sets the clearance left between piston and head.

The two brands

	Athena S.p.A. is an Italian maker of gaskets and engine parts, based in Alonte, in the Veneto, with production sites in Spain, the United States, Brazil and India. Its multi-layer gaskets are fitted as original equipment by car manufacturers, and its competition range is designed and built entirely in Italy.
	Cometic Gasket, Inc. is an American company based in Concord, Ohio, since 1989. It designs gaskets and sealing solutions for engines, and its reputation comes from the made-to-order gasket, cut to the bore and thickness requested. All production stays 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 bore size of the original gasket, which neither Ford nor Mazda publishes 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: 1 124 372, 1 129 043, 1 229 872, 1S7G 6051AJ, 30 777 325, L3G2-10-271A, L309-10-271, LF3F-10-271.

Important: the part numbers on this page match the Ford and Mazda engines listed above: note your vehicle's engine code, then check the bore before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches its limits, the reinforced gasket takes over: under higher combustion pressure it holds its shape instead of being crushed.

With a turbo, a supercharger or a raised compression ratio, the head works harder and the gasket becomes the most tested part of the top end. A reinforced gasket rules out the gas or coolant leak and the head removal that follows, with the vehicle off the road.