How Spark Plug Work In Trucks

A spark plug is one of the electrical components of the petrol engine. And it sits on top of each of the engine cylinders. In the cylinder, the combustion of fuel and air occurs. For the combustion to occur, the mixture of fuel and air requires ignition, and the spark plug generates the spark.

The combustion engines depend on the spark plug to initiate combustion within the cylinders. The spark plug receives electric power from the battery. This power generates sparks in the cylinder, which initiates combustion.

Functions of a Spark Plug

Here are the two primary functions of a spark plug.


The spark plugs depend on the electricity from the battery to cause an ignition. The energy is transmitted through the spark plug to the firing end within the cylinders. When the voltage is high enough, it will spark the mixture of gasoline and air in the cylinder. The gasoline and air mixture will burn upon ignition, making the piston move up and down. The up-and-down movement of the piston rotates the crankshaft.

Heat Dispersal

During combustion, the temperature goes up within the cylinders. The spark plug plays a role in dispersing the high temperatures. Spark plugs never generate heat, but they only remove the generated heat. The spark plug’s firing end must have a low temperature to prevent a pre-ignition, but this temperature should also be relatively high to prevent fouling.

The spark plug pulls the unnecessary heat from the combustion chamber to the engine’s cooling system. Spark plugs have a hitting range that is their ability to perform an effective heat dispersal from the tip.

How Spark Plug Works

The spark plug directly connects to the ignition coil, which supplies it with high voltage. The electrode flow in the coil initiates a voltage difference between the electrode’s side and center. In the cylinder, no current can flow due to the existence of the mixture of gasoline and air that acts as an insulator. But as the voltage keeps rising, the structure of the gases between the electrodes starts to change.

When the strength of the voltage exceeds the dielectric strength of the gases, they become ionized. An ionized gas conducts electricity and, therefore, allows the electrons to flow through the gap that is the gasoline and air mixture. Spark plugs usually require a high voltage of more than 20,000 volts to initiate combustion.

The fluctuation of the current of the electrons in the combustion chamber leads to an increase in the temperature of the spark channel. Due to the extreme heat, the ionized gases rise very fast, initiating small explosions like thunder and lightning.

The reaction of gases at the end of the spark plug leads to the generation of a small ball. The size of the fireball varies. A small fireball makes the engine run as if the ignition timing is retarded. On the other hand, a big fireball makes the engine run as if the timing is advanced.


The spark plug is an integral component of a gasoline engine. As a truck owner, it is necessary to know how it works per this guide. It is one of the engine components that require regular maintenance. Knowing its location and how to replace it is an added advantage.

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