MLS Head Gasket

(.040" Over x .040" Thick)

The cylinder head gasket is arguably the most important seal in an automotive engine. Since the release of the internal combustion engine, gasket designers have specified many materials to meet this critical sealing challenge. Traditional copper and brass gaskets gave way to metal and asbestos in the 1950s, which in turn were superseded by composite metal and impregnated fiber/graphite composites by the 1980s. However, those systems were largely overtaken by the development of the Multi-Layer Steel (MLS) gasket in Japan during the early 1990s.

MLS gaskets remain the automotive industry's preferred method of sealing between the cylinder head and engine block, as yet unmatched by any other sealing system. Today an estimated 80 percent of new engines are designed with MLS gaskets as standard equipment, and further growth is projected. In the MLS system, multiple thin layers of cold-rolled spring grade stainless steel are coated with 7-25 microns of elastomeric material. The resilient elastomer is essential to the structure by providing micro-sealing of metal surface imperfections while resisting aggressive combustion gases, oils, and coolants at temperatures up to 250C. The surfacing needs of today's engines are as complex as the engines themselves. Multi-valve aluminum cylinder heads on cast iron blocks are a tough combination to seal because of the difference in expansion rates between the two metals. If the surface finishes on the head and block are too rough, lateral shearing forces that occur as the engine heats up and cools down can scrub a head gasket to death.

To handle such forces, a growing number of late model engines now use multi-layer steel (MLS) head gaskets. These include many Ford, Chrysler, Honda/Acura, Mazda, Mitsubishi, Nissan, Subaru, and Toyota engines. MLS gaskets typically have 3 to 5 layers of steel and are extremely tough. But they have little conformability and require a very smooth finish on both the block and cylinder head to seal correctly. OEM specifications vary, but surface finish requirements for MLS head gaskets are 8 microinches Ra or less.

The ability to duplicate OEM surface finishes is a must on these applications, especially if OEM style MLS gaskets are being installed in the engine. Some aftermarket replacement gaskets for these engines have a thicker surface coating that can accommodate a more "traditional" surface finish of up to 60 microinches Ra. But most MLS replacement gaskets require the same surface finish as the original; which means engine builders must have surfacing equipment that can duplicate a finish that meets OEM specifications. MLS gaskets have also become very popular in racing. Most NASCAR engines today are running MLS gaskets, and the people who are putting these engines together typically want finishes in the low teens or even single digits! That level of smoothness can only be obtained with equipment that has the rigidity, accuracy and control flexibility to produce an ultra-smooth finish. LC Engineering can produce a finish on both the head and block in house.

NOTE: This gasket will be utilized on all 93mm bore blocks. This gasket displays 94mm on packaging to allow 20 thousandths of an inch play when installing the cylinder head. The last thing you want is for the gasket to stick into the bore.

Contact our Tech Support Line for further information at 928-575-2174.