Clean, smooth and flat. These are the basic requirements for replacing virtually any type of gasket. If the surface on the parts that are being mated with a gasket are not perfectly clean (no old gasket residue, grease or oil), smooth (not too rough or scratched) and flat (within certain flatness specifications), the gasket may leak or fail to provide a long-lasting seal.
Gaskets are commonly replaced to repair oil leaks, coolant leaks, exhaust leaks and vacuum leaks. New gaskets are also required when removing pan covers, valve covers, timing covers, intake manifolds, exhaust manifolds, thermostat housings, throttle bodies, water pumps and cylinder heads. So there are ample opportunities to sell your customers gaskets.
Gasket sets are always recommended because a set includes all of the parts that are commonly required for a specific type of repair. Many do-it-yourselfers may not know that certain gaskets (such as silicone rubber valve cover gaskets and seals) may not be reusable because of the swelling that occurs in rubber silicone gaskets over time.
The type of gasket that is used for a particular application as well as the quality of the materials that are used in the gasket can often make the difference between a temporary repair and a long-lasting repair. This is especially true with head gaskets and intake manifold gaskets.
Many late-model engines have Multi-Layer Steel (MLS) head gaskets because this type of gasket is extremely tough and long lasting. Aftermarket gasket suppliers have developed MLS replacement head gaskets for many older “problem” applications that were originally equipped with some other type of head gasket (graphite, nonasbestos composite or embossed steel). Upgrading to a MLS head gasket instead of a conventional replacement gasket can solve the weakness in the original gasket design that led to the failure.
One of the keys to installing MLS head gaskets is to make sure the surface on the heads and block have a high-quality finish. Many original equipment MLS head gaskets require very smooth surface finishes of 30 microinches or less, but improved surface coatings on most aftermarket MLS gaskets can tolerate finished up to 50 or 60 microinches. MLS gaskets are installed dry with no sealer. Also, if the engine has torque-to-yield (TTY) bolts, the original head bolts should be discarded and replaced with new TTY head bolts. Reusing TTY bolts is not recommended because of the risk of breakage.
Cork/rubber cut gaskets for valve covers and oil pans are relatively inexpensive parts, but don’t provide the same durability as molded gaskets. Replacement upgrades include solid high-temperature synthetic rubber molded gaskets and molded gaskets laminated around a steel center core. The steel reinforcement provides stiffness and helps the gasket hold its shape. Compression-limiting grommets also may be used in the gasket to control crush when the gasket is installed. Molded gaskets are also installed dry with no sealer.
For leak-prone, carrier-style OEM intake manifold gaskets that are used on many V6 and V8 engines, aftermarket replacement gaskets that utilize an aluminumized steel carrier rather than plastic can provide added durability. The sealing surfaces on many of these gaskets also incorporate multiple beads or ridges to compensate for corrosion that may have taken place around coolant ports. Tougher materials such as Viton may also be used for the sealing beads around the ports to reduce the risk of leaks developing down the road.
Worn crankshaft end seals are a common cause of oil leaks on many engines. Replacement seals that are made of PTFE (Teflon) should be installed dry (not prelubed with oil) to seal properly. Other types of seals, however, should always be lubed when they are installed.
