Reinforced cylinder head gasket Ford Mondeo V Mazda 3 5 6 CX-7 2.5 S7CB L5-VE

The Ford and Mazda engines covered

The petrol engines S7CB (Ford) and L5-VE (Mazda), 2.5-litre four-cylinders, are the engines covered by this page. They power the Ford Mondeo V and the Mazda 3, 5, 6 and CX-7 models in the compatibility table below, from 2007 to 2022.

Two original gaskets are fitted to these engines: 2 328 336 for the S7CB and L501-10-271 for the L5-VE. Ford and Mazda publish neither their bore, nor their thickness, nor their construction. They are sized for standard combustion pressure: as soon as it rises, the clamping load drops, the head lifts and coolant passes into a cylinder.

Reinforced cylinder head gaskets

The head is held to the block by studs or bolts that provide half of the sealing on their own: the gasket never works alone. A composite gasket is permanently compressed from 100 N/mm², whereas the 301 stainless steel of an MLS gasket withstands 517 N/mm², five times more, and regains its shape at every combustion.

This page groups two part numbers from Athena, an Italian maker of racing gaskets, for a single construction: the multi-layer steel MLS. Both have a 91.0 mm bore and differ only in thickness, 0.7 or 1.0 mm. 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 room it leaves free above each cylinder. It adds to the combustion chamber and lowers the compression ratio; as both part numbers share the same bore, the 1.0 mm gasket lowers the ratio more than the 0.7 mm one.

Preparation and fitting

Before reassembly, check the flatness of the head and block faces with a straight edge and have them machined if necessary. The Athena gasket comes coated: do not add any sealing paste.

Technical guide

The construction offered

Athena MLS A stack of two to five AISI 301 stainless steel sheets, laser cut, stamped, then riveted. Around each cylinder, a folded sheet called the Gas Stopper concentrates the clamping force on the combustion chamber, while embossed beads isolate the water and oil circuits. Both faces receive a double coating: the first withstands high temperatures and fills small flaws in the block and head, the second, in silicone, stops the gasket sticking at removal. It is Athena's all-steel solution, from the prepared naturally aspirated engine to moderate forced induction.

Choosing bore and thickness

Gasket bore. The Athena MLS is offered in 91.0 mm only (338473R and 338474R).

Thickness. Ford and Mazda do not give the thickness of the original gasket. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

As the original thickness is not published, use a dial gauge to measure how far the pistons stand proud of the block face, especially if you are aiming at 0.7 mm: that figure fixes the distance left between piston and head.

The brand

Athena S.p.A. is an Italian company making gaskets and sealing parts for engines. Its head office and main plant are in Alonte, in the Veneto, with further sites in Spain, the United States, Brazil and India. Some carmakers trust it for original fitment, and its 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 original gasket, which Ford and Mazda do not publish 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: 2 328 336 and L501-10-271.

Important: these two part numbers are reserved for the engines S7CB and L5-VE: check your car's engine code 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 keeps its thickness and shape without being crushed.

Fitting a turbocharger or supercharger, or raising the compression ratio: the more power you add, the more the head gasket becomes the weak link of the top end. A reinforced gasket prevents the leak, and the cylinder head removal that follows, which costs far more than the gasket itself.