Reinforced cylinder head gasket Toyota 4A-GE 4A-GEC 4A-GELC 4A-GEL 4A-GZE

The Toyota engines covered

The 4A-GE, 4A-GEC, 4A-GELC, 4A-GEL and 4A-GZE are 1.6-litre Toyota four-cylinder petrol engines: the 4A-GE comes with 16 and with 20 valves, the others have 16 valves. The 4A-GZE is supercharged, the others are naturally aspirated. They power the Toyota Corolla, Corolla Levin, Corolla FX, Sprinter, Celica, Carina, MR2 and Conquest models in the compatibility table below, and each takes a single cylinder head gasket.

The original gasket of the 16-valve engines carries part number 11115-16070. Toyota does not publish its bore, thickness or construction. It is calibrated for the standard combustion pressure: as soon as it rises, the clamping load weakens, the head lifts and coolant seeps into a cylinder.

Reinforced cylinder head gaskets

The gasket does not guarantee the seal on its own: the fasteners that clamp the head to the block matter just as much. Above 100 N/mm² of stress a composite gasket is crushed for good; the 301 stainless steel of MLS gaskets withstands up to 517 N/mm², 5 times more, and springs back with every combustion.

This page groups 55 MLS part numbers from two competition makers, Cometic (United States) and Athena (Italy), all in multi-layer steel construction. Cometic offers bores of 81 and 83 mm and Athena bores of 81, 83 and 83.5 mm, in thicknesses from 0.69 to 3.56 mm, enough to set the compression ratio to suit the build. The engine takes a single gasket: order one part number, according to the bore and thickness you want.

Technical specifications

The volume of a gasket is the free space it leaves above each piston: it adds to the combustion chamber and lowers the compression ratio. Only gaskets of the same bore can be compared, and the bores differ here between Cometic and Athena.

Preparation and fitting

Before assembly, check the flatness of the head and the block with a straightedge and have any warped surface machined. Cometic and Athena supply their gaskets already coated: do not apply sealing paste.

Technical guide

The two constructions offered

Athena MLS Athena MLS A stack of two to five AISI 301 stainless steel layers, laser cut, stamped and then riveted. A folded layer rings each cylinder: this Gas Stopper concentrates the clamping force on the combustion chamber, while beads isolate the water and oil circuits. Each outer face is coated: one coat withstands high temperatures and takes up small flaws in the block and head, a silicone coat stops the gasket sticking at removal. It is Athena's all-steel solution, from the tuned naturally aspirated engine to moderate forced induction.

Cometic MLS Several stainless steel sheets, stamped, stacked and then riveted. The two outer sheets carry active beads around every cylinder and every fluid passage. A moderate clamping load is enough to seal, and the bore distorts very little: a versatile construction, from the tuned naturally aspirated engine to moderate forced induction.

Choosing bore and thickness

Gasket bore. The Cometic MLS comes in 81 mm (C4170 and C4604, from 0.69 to 3.56 mm) and in 83 mm (C4166, C4605 and H2627075S); the Athena MLS comes in 81 mm (338213R), in 83 mm (338214R, 338323R and 338324R) and in 83.5 mm (338575R and 338576R).

Thickness. Toyota quotes no thickness for its standard gasket. 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 the pistons stand above the block deck before you order, especially for a gasket thinner than the removed one: this figure gives the real clearance between piston and head.

The two brands

	Athena S.p.A. is an Italian maker of gaskets and engine parts. Its head office and main plant are in Alonte, in the Veneto, and the group also operates in Spain, the United States, Brazil and India. Its multi-layer gaskets are fitted as original equipment by several car makers; the competition range is designed and built entirely in Italy.
	Cometic Gasket, Inc. is an American maker of gaskets and sealing solutions for engines, founded in 1989 and based in Concord, Ohio. It is known for made-to-measure gaskets, cut to the bore and thickness ordered, built entirely 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 81, 83 and 83.5 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: 11115-16070.

Important: these part numbers are for the 4A-GE (16 and 20 valves), 4A-GEC, 4A-GELC, 4A-GEL and 4A-GZE engines: check your vehicle's engine code and valve count before ordering, then choose the bore and thickness you want.

Why switch to a reinforced gasket?

When the original gasket reaches its limit, the reinforced gasket takes over: at a higher combustion pressure it keeps its shape instead of being crushed.

As soon as a turbo or supercharger is added, or the compression ratio is raised, the head gasket becomes the first weak point of the top end. A reinforced gasket spares you the leak, and the head removal that follows, a far costlier job.