Gaskets exist to provide a seal between two surfaces of the engine. Engines, on account of their material and the fact they are an engine, are subject to change in temperature and pressure while engine parts are subject to movement.
The engine, being heated and cooled, is subject to pressure from compression and vacuum, while engine parts expand and contract, move away from each other and are drawn tighter.
Because the engine is subject to force and stress in every direction, the gaskets are heated, cooled and rubbed. A cold gasket acts differently than a hot gasket, and a gasket when subjected to increased pressure acts differently than when the pressure is decreased.
Follow along as we check out the different gaskets that fit on your vehicle.
What is an Engine Gasket?
In the engine, the gasket is used between the cylinder head and cylinder block to prevent leakage and also to make tight metallic fit joint. It is also to maintain compression in the cylinder. The gasket should be able to withstand high pressure and extreme temperatures.
Gaskets are also found:
- Between the cylinder head and the cylinder block.
- Between crankcase and oil pan.
- In the cylinder block and manifold.
Requirements/Properties of the Gasket as Follows
- Conformity: The gaskets that are based on softer materials should conform to the two mating surfaces which may have roughness or warpage.
- Resistance: It should have resistance to high pressures, extreme temperatures, and vibrations.
- Impermeability: The gasket must be impermeable to the fluid.
- Resistance to chemical attack: The gasket should be resistant to chemicals like fuel, coolant, products of combustion, engine oil, etc.
- Provision of apertures: Gaskets must have apertures for any studs, bolts, openings, etc.
Functions of a Gasket
The function of an engine gasket is insulation between the cylinder block and cylinder head. Such insulation prevents oil leakage thus oil will not overflow into the radiator channel, or the reverse will not happen.
The gasket’s ability to hold this pressure is one more way it keeps itself from leaking from the cylinder head into a space between the two blocks. An automobile engine is an engine block with a cylinder head on top.
Car gaskets transfer heat from the cylinder block to the head block. Metal packing is commonly used as the gasket. The two functions tend to be closely associated.
Types of Gaskets
The following are some of the different types of gaskets:
- Cylinder head Gasket
- Valve Cover Gasket
- Oil pan Gasket
- Manifold Gaskets
- Pump Gasket
Cylinder Head Gasket
Metal sandwich-type gasket. Made of copper and asbestos or steel and asbestos; used mainly on passenger cars and trucks.
Embossed steel or shim type gasket. Usually used on I-head engine; present-day shimbestos is buildup of a thin steel heat shield on one side and a high resilient metal-reinforced asbestos on the top side.
Felbestos is Made up of perforated steel sandwich between two asbestos sheets.
Valve cover gasket.
Situated between a comparatively thin steel cover, cast aluminum or plastic composite cover and a cylinder head that is cast of iron, aluminum, or alloy (mixture of metals or metals plus non-metals).
When the engine is first started on a cold day, the oil that flows through the system could be 32°F or colder. The gasket, like the head and valve cover, are just as cold. AS the engine warms up, the oil, head, cover and gasket warm up at different rates.
The heat generated by the friction in the head and engine block heats the oil. Therefore, the heat radiated by this source, plus the heating effect of the oil, tends to heat the valve cover.
After noting that this process continues over many thousands of miles and time and engine heating and cooling cycles, one can readily appreciate why the valve cover gaskets may no longer do their job of sealing and oil leaks out.
Oil Pan Gasket
The oil pan gasket also sits below the engine block, down in the portion of the engine referred to as the crankcase—the place where the crankshaft lives. It is compressed between the crankcase and a stiffened steel pan or cast pan.
The pan is a relative thinner than the crankcase, generally cast from iron, aluminum or alloy. The same physical aspects that come into play with the valve cover gasket and head gasket affect the oil pan gasket.
Oil resides in the oil pan when the engine is not running and to return to while running. As the engine warms on a cold winter day, so do the oil, pan and gasket. When the engine is turned off and the hot oil returns to the pan, the three of them cool at different rates.
Over time a stressed oil pan gasket can fail at different times, either under the cold condition, the warm condition, or under the moving condition of the pan against the case.
Intake Manifold Gasket
Intake gaskets are typically made from aluminized steel coated with a carbon-based rubber compound, paper bonded to a metal core or molded rubber, this gasket seals the intake manifold to the cylinder heads.
High-quality intake manifold gaskets are typically designed in a one-piece layout with embossments and sealing beads formed on the ports or runners. These gaskets should be resistant to PCV oil, coolant decay and of course, fuel. High-quality intake manifold gaskets are essential to the performance of your engine.
In the case of intake manifold gasket failure, leaking coolant on the outside of the manifold will occur. Your engine is shedding coolant, and the bloated “warm engine” sensor will prompt the engine to shut down before it can overheat itself. If not addressed quickly this can cause eternal damage to your cylinders and block.
The type of failure experienced at the intake runner port location is one more vacuum leak condition, causing rough running, high fuel consumption and the Check Engine light would also occur.
Pump Gasket
Pump gaskets are manufactured from various materials, including asbestos, karropak and felcoidsand others.
They are treated to resist oil, water, petrol and anti-freeze fluids. Karropak is made from a very superior vegetable fibre and Felcoid is a type of rough cellular substance made from united pieces of fibre and cork granules; it is more compressible & flexible.
Timing Cover Gasket
The timing cover is the cover at the front of the engine behind which lies the timing chain. The timing cover gasket is fitted between the cover and the engine block and serves to seal in coolant and oil.
The sealing material in the gasket can be scrubbed off with the action of the zenith and nadir of the timing cover; resulting it may be failure. This may leak coolant or oil, and in particular leak coolant into the crankcase, contaminating the oil.
Gaskets Coating Materials
Often the gaskets are coated with some special varnish which as the engine warms up melts and fills up all the little interstices of the block and of the head. Examples of the coating material are as follows.
- Copper-asbestos
- Steel-asbestos
- Steel-asbestos-copper
- Single steel ridged or corrugated gasket
- Stainless steel
Holes are cut in the gasket to pass the studs and for the cylinder bore. Gaskets are also used to seal joints between other parts, as between oil pan, manifolds or water pump and the block.