What is a Head Gasket and what is its Purpose?

 

              A head gasket is a gasket that sits between the engine block and the cylinder head in an internal combustion engine. The purpose of the head gasket is to create a seal for the cylinders to provide the most compression and to help prevent the engine coolant or engine oil from leaking into the cylinders. It is the most important sealing application in any engine. Because it is part of the combustion chamber, it has the same strength requirements as other components.

              There are several different types of head gaskets. Some are what are referred to as MLS or Multiple Layers Steel. Obviously the name says it all. It’s made out of steel and most modern head engines are made from this material.  Another type is made out of solid copper which usually goes through a special machining process called ‘o-ringing’. This makes the copper gaskets extremely durable. Recently, companies have started using this technology. Composite gaskets is a technology of years passed which were made from asbestos or graphite but are more susceptible to blowouts than the newer ones. Also with recent studies on asbestos and the health concerns associated with is, asbestos gaskets are now a rarity.

              To get a replacement head gasket itself is not a huge expense. However, the price of total repair is very costly. This is due to the labor. It is a time consuming process because the mechanics have to remove and replace the engine head. About 75% of the repair cost is just labor. Also, if a blown head gasket goes ignored, it invariably causes extreme damage to the engine.

              A typical internal combustion engine is a water-cooled four-stroke petrol design which uses 3 circuits of working fluids:

1.       Combustible air/fuel mixture

2.       Water based coolant

3.       Motor oil for lubrication

These are all extremely important to the proper running of an engine but they are never allowed to mix. In addition to sealing the cylinder, the head gasket also seals water and oil conduits between the head and block. If any forms of mixture between these fluids happen, it will cause engine failure or other major problems such as burning oil (blue smoke from the exhaust) or coolant burning (white exhaust smoke) all are symptoms of gasket wear.