What is a Head Gasket in Cars and How it Works?

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Car is a reflection of fine engineering. Propelled by a combustion engine,  it is an assemblage of several elements. Among them, a head gasket holds a major significance. This small yet crucial element is fitted between the engine block and cylinder head. 

The primary purpose of it is to fasten the inner combustion process allowing oil and refrigerant to flow freely to lubricate and cool down the engine.

Head gaskets are multi-layered machine-casted components manufactured specifically for inner combustion engines. They come with tubular bored holes for hosting pistons. It maintains an optimum compression ratio across the chamber, allowing your car's engine to perform flawlessly. 

Though usually a gasket is made of a composition of steel and elastomer, it can also be developed using copper, silicone, or rubber. 

Most vehicles' engines comprise two parts: an engine block and a cylinder head dashed on top. While engine blocks house pistons and cylinders, cylinder heads contain spark plugs, camshafts, and valves. 

Cushioned between them, a head gasket acts as a seal resisting leakage of engine fuel and pressure losses. Placed on the cylinder head, it creates a barrier between the oil and the coolant.

Head gaskets perform certain functions that directly sync in improving the service life of an automobile engine. Here is a detailed overview:

Maintenance of pressure

This is the principal task of a gasket. It confines the combustion chamber allowing your vehicle to produce sufficient compression. The ideal pressure accelerates the engine’s power.

Keeping an optimal temperature

Since a combustion chamber holds the fuel, it overheats while driving. A head gasket secures the cooling channels between the engine block and the cylinder head to maintain an optimal temperature. 

Acting as a separator

A gasket performs the crucial task of segregating the oil and coolant passages to prevent any mix-up. Not only does it resist any leakage, but it also repels the risk of detonation.

Being made after extensive research and using premium quality materials, a gasket is rigid and comes with an enduring operational life. However, certain conditions can trigger premature failure of a gasket. 

Let's understand the reasons behind the breakdown first before moving to the consequences:

Engine overheating

This is the most accepted cause of gasket failure. When an engine gets too hot to handle, it damages the gasket. The excessive heat can also deform the chamber head or block, making it unable for a gasket to seal.

Pre-ignition

Pre-ignition is a condition when the fuel and compressed air or refrigerant accidentally mix up, resulting in a spark. Inarguably, this is another reason behind an untimely blown gasket. It creates acute emphasis on the gasket leading to its premature failure.

Hasty temperature alterations

Since a head gasket has thermal properties, it expands and collapses as per the engine temperature. Activating an engine and immediately ceasing it results in sudden temperature changes that pessimistically affect the lifespan of a gasket.

Ageing

Similar to other existing components, ageing is another reason behind a blown gasket. After covering a significant mileage, it is recommended to replace the gasket. If unchanged, then it may lead to serious damage as the sealing power of a gasket wears out with time.

Flawed installation

Last but not least, if a gasket has not been installed correctly, then it will not be able to last for a long time. Imprecise installation attracts premature failure. Moreover, incorrectly equipped gaskets are unable to seal the cylinder head properly, increasing the risk of detonation.

As per the condition's gravity, motorists can encounter several symptoms. Some of them are as follows:

Persistent leakage

Leakage of oil and coolant is the most noticeable sign when it comes to blown head gaskets. When a gasket fails to seal properly, fuel and refrigerant ooze from the engine block.

Misfire

A faulty gasket can no longer keep the coolant and oil separated. Thus, the refrigerant leaks into the cylinder and disbalances the oil and air ratio resulting in a misfire.

White vapour

As a sequel to the previous symptom, when the coolant burns in the cylinder, it turns into a composition of white smoke and water vapour and releases through the vehicle's exhaust. Hence, the egression of white vapour from your car's tailpipe is another sign of head gasket failure.

Milky-coloured oil

If you have experienced any of the enlisted symptoms, then look at the dipstick. If the oil has transformed into a whitish/milky shade, then the coolant has already blended with the oil. It also leaves residue on the oil filler cap.

The cost of a gasket depends on several factors. The manufacturer, applicable vehicle, and materials used play a crucial role in the price determination of a gasket. In India, the average cost of a head gasket ranges from ₹500 to ₹12000. Though the prices may seem a bit expensive, fixing a blown gasket is worthwhile as it secures the engine from further damage. 

Hopefully, this piece has mended all your queries about a head gasket. This small yet significant element of a car’s engine keeps the coolant and oil separated and unmixed. Overheating of an engine or incorrect installation can decrease a gasket’s lifespan. Thus, proper maintenance of the engine will secure an extensive operational period for the gasket.