Reinforced head gasket Peugeot Citroën 2.0 16V XU10J4RS

The Peugeot and Citroën engines covered

The XU10J4RS is a 2 litre (1,998 cc) sixteen-valve petrol engine. It powers the Citroën Xsara Coupé and ZX and the Peugeot 306 listed in the compatibility table below, and takes a single head gasket.

The original gasket carries the part number 0209.Z2. The manufacturer publishes neither its bore, nor its thickness, nor its construction. Designed for the standard combustion pressure, it reaches its limit as soon as that pressure climbs: the clamping force eases, the head lifts slightly and coolant enters a cylinder.

Reinforced cylinder head gaskets

Sealing does not rest on the head gasket alone: it also depends on the fasteners that clamp the head to the block. A composite gasket is permanently crushed beyond 100 N/mm²; the 301 stainless steel of MLS gaskets withstands 517 N/mm², 5 times more, and recovers its shape at every combustion. So also check the XU10J4RS head bolts before reassembly.

This page brings together thirty-seven part numbers from two competition manufacturers, Athena (Italy) and Cometic (United States), all in MLS construction, multi-layer steel. Athena offers two part numbers in an 87 mm bore: 338263R at 1.3 mm and 338264R at 1.6 mm; Cometic offers thirty-five: seventeen C4520 in an 86.5 mm bore and eighteen C4521 in an 88 mm bore, all from 0.69 to 3.56 mm. The engine takes a single gasket: order one part number, according to the bore and thickness you want.

Technical specifications

A gasket's volume is the free space it leaves above each cylinder. Added to the combustion chamber, it lowers the compression ratio. Only gaskets of the same bore can be compared: the Athena is 87 mm, the Cometic C4520 is 86.5 mm and the Cometic C4521 is 88 mm.

Preparation and fitting

Before fitting, check with a straight edge that the head and block are flat, and have them resurfaced if needed. Athena and Cometic supply their gaskets coated: do not apply any sealant. Do this on the head and on the block of your Xsara, ZX or 306.

Technical guide

The two constructions offered

Athena MLS Athena MLS Two to five AISI 301 stainless steel sheets, laser-cut, embossed and riveted. A folded sheet surrounds each cylinder and forms a Gas Stopper that concentrates the clamping force on the combustion chamber, while beads seal off the water and oil circuits. Both outer faces are coated: one layer withstands high temperatures and fills small flaws in the block and head, one silicone layer stops the gasket sticking on removal. It is Athena's all-steel solution, from the tuned naturally aspirated engine to moderate boost. It supplies part numbers 338263R and 338264R here.

Cometic MLS A stack of embossed stainless steel sheets assembled with rivets. The outer sheets carry active beads that surround each cylinder and each fluid passage. Moderate clamping is enough to seal and the bore distorts little: a versatile construction, from the tuned naturally aspirated engine to moderate boost. It supplies the C4520 and C4521 part numbers here.

Choosing bore and thickness

Gasket bore. The Athena MLS is offered here in 87 mm (338263R, 338264R) and the Cometic MLS in 86.5 mm (C4520) and in 88 mm (C4521).

Thickness. The manufacturer publishes no thickness for the original gasket 0209.Z2. A thicker gasket enlarges the combustion chamber and lowers the compression ratio; a thinner one reduces it and raises the ratio.

As no original thickness is published, use a dial gauge to measure how far each piston protrudes above the block's gasket face, especially before resurfacing: this reading gives the clearance left between piston and head. On this four-cylinder engine, take that measurement at each of the four pistons.

The two brands

	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 multilayer gaskets are fitted by car makers as original equipment, and its whole competition range is designed and made in Italy. Here, these are part numbers 338263R and 338264R on this page.
	Founded in 1989 in Concord, Ohio, Cometic Gasket, Inc. is an American company that designs and makes engine gaskets and sealing parts. It owes its reputation to custom gaskets cut to the bore and thickness required, produced in the United States from American raw materials. Here, these are the C4520 and C4521 part numbers on this page.

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 bores of the gaskets offered (87 mm for Athena, 86.5 mm and 88 mm for Cometic) 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: 0209.Z2.

Important: the part numbers on this page suit only the XU10J4RS engine: check your vehicle's engine code before ordering.

Why switch to a reinforced gasket?

When the original gasket reaches its limit, the reinforced gasket takes over: under higher combustion pressure it keeps its shape and does not crush. The XU10J4RS is no exception.

As soon as power goes up, through a bigger turbo, a supercharger or a raised compression ratio, the head gasket is the first part of the top end to give way. A reinforced gasket avoids the leak and the head removal that follows, a job far more costly than the part. On the XU10J4RS, it is the first point to watch.