Reinforced head gasket Toyota 2AZ-FE

The Toyota engines covered

The 2AZ-FE is a four-cylinder petrol engine of 2.4 litres. It is found in the Toyota Camry, Highlander, RAV4, Previa, Alphard, Matrix and in further models, detailed below.

On this engine the factory gasket is the 11115-28010. Toyota gives out neither its bore, nor its thickness, nor its construction. Its setting matches the original combustion pressure: when that pressure rises, the clamping force weakens, the cylinder head shifts on the block and coolant finds its way into a cylinder.

Reinforced cylinder head gaskets

The gasket is not the whole story: the fasteners that clamp the head onto the block provide half of the seal. Beyond 100 N/mm² of stress, a composite gasket settles permanently; the 301 stainless steel of MLS gaskets withstands 517 N/mm², 5 times more, and springs back with every combustion.

Two Cometic part numbers, from an American maker of gaskets for competition, are gathered here, both in MLS construction: the C4507 for an 89 mm bore and the C4506 for a 92 mm bore. Each comes in eighteen thicknesses, from 0.69 to 3.56 mm. The usual rule is that the gasket bore exceeds the cylinder bore by at least 0.5 mm. The gasket is ordered singly: one gasket is enough for one engine.

Technical specifications

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

Preparation and fitting

Before fitting, rest a straightedge on the cylinder head and then on the block, and have any warped surface machined. This Cometic gasket is supplied coated: add no sealing paste to it.

Technical guide

The construction offered

MLS Cometic Stamped stainless steel sheets, laid one over another and then riveted. The outer sheets show active beads around every cylinder and every fluid passage. A moderate tightening is enough to seal and the bore distorts little. A versatile gasket, from the tuned naturally aspirated engine to moderate boost.

Choosing bore and thickness

Gasket bore. The Cometic MLS gasket is available in 89 mm (C4507) and 92 mm (C4506), and in those two bores only.

Thickness. No thickness is released by Toyota for 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 unknown, use a dial gauge to read how far the pistons stand proud of the block deck, above all when aiming for a thickness below that of the removed gasket: this reading gives the true gap between piston and cylinder head.

The brand

Cometic Gasket, Inc. designs gaskets and sealing parts for engines. The American company, created in 1989 in Concord, Ohio, made its name with the made-to-measure gasket, cut to the bore and thickness requested, and with manufacturing that remains wholly American, using local 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 89 and 92 mm bores of the 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: 11115-28010.

Important: the two part numbers on this page suit the 2AZ-FE engine: check your vehicle's engine code before placing your order.

Why switch to a reinforced gasket?

Once the original gasket reaches its limits, the reinforced gasket takes over: subjected to a higher combustion pressure, it is not crushed and keeps its shape.

Adding a turbo or a supercharger, or raising the compression ratio, puts the head gasket to the test first, the weak point of the top end. A reinforced gasket avoids the leak and the head removal that follows, a job far costlier than the gasket itself.