Reinforced head gasket Volvo 850 S70 V70 C70 S60 S80 2.3 T5 B5234T

The Volvo engines covered

The Volvo 2.3 litre five-cylinder turbocharged petrol engine, identified by the codes B5234FT, B5234T2, B5234T3, B5234T4, B5234T5, B5234T7 and B5234T8, powers the Volvo 850, S70, V70, C70, S60 and S80 models listed below.

For these engines the manufacturer lists the original gasket 9 135 513; it publishes neither its bore, nor its construction, nor its thickness. It is sized for standard combustion pressure: when it rises, the head loosens, lifts and lets coolant pass into a cylinder.

Reinforced cylinder head gaskets

The gasket does not guarantee the seal by itself: the fasteners that pull the head down onto the block count just as much. The CFM-20 combines a galvanized steel core with a soft asbestos-free compound that fills small irregularities in the sealing faces.

This page offers one part number from the American maker Cometic, a specialist in racing gaskets, in a single construction: CFM-20. Its bore is 84 mm and its thickness 1.50 mm. It is sold individually, one gasket per engine.

Technical specifications

The volume of a gasket is the free space it leaves above each cylinder. It is added to the combustion chamber and lowers the compression ratio; only gaskets of the same bore can be compared.

Preparation and fitting

Before fitting, check the flatness of the head and the block with a straightedge, then have either one resurfaced if necessary. Cometic inspects the flatness of every one of its CFM-20 gaskets.

Technical guide

The construction offered

Choosing bore and thickness

Gasket bore. The Cometic CFM-20 is offered in 84 mm (H1508SP4059F), with no other bore.

Thickness. The manufacturer gives no thickness for the original gasket 9 135 513. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

With no original thickness published, use a dial gauge to measure how far the pistons stand above the deck of the block, above all if the removed gasket is thinner than 1.50 mm: this figure gives the clearance that remains between piston and head.

The brand

Founded in 1989 in Concord, Ohio, the American company Cometic Gasket, Inc. designs gaskets and sealing solutions for engines. It made its name with the made-to-order gasket, cut to the bore and thickness wanted; all of its manufacturing stays in the United States, using 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 84 mm bore of the gasket 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: 9 135 513.

Important: the part number on this page fits only the B5234FT, B5234T2, B5234T3, B5234T4, B5234T5, B5234T7 and B5234T8 engines: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket hits its limit, this CFM-20 takes over: the steel core holds its shape under combustion pressure, and the soft compound on both faces follows the small flaws of the head and block.

When an engine runs close to its limit, the head gasket is often the first part to give. A reinforced gasket prevents the leak, whereas the head removal that follows, with the car off the road for days, costs far more than the gasket.