Glow plugs and spark plugs are considered to be similar despite they have several differences between them. Talking about the similarities, all engine combustion require three things, i.e. the fuel, air and heat or a source of ignition. Both glow plugs and spark plugs work as a source of ignition during the combustion of the engine. The main difference between the two is just the type of engine they are actually found in. As we all know, spark plugs are found only in gasoline engines and glow plugs are found in diesel ones.
With the difference in the engine type they are found, there also comes a slight difference in the functionality of the same. Let us understand how both plugs differ from each other.
A spark plug is known to be the essential part of your ignition, as your vehicle won’t start without it. Technically, it is known as the electrical component which is placed in the cylinder head of the engine. At this place, it receives a high-voltage from the ignition coil. A spark plug runs continuously to make sure that your engine keeps on running. In a gasoline car, the working of the engine is quite different. In this, the fuel is mixed with the intake air inside the throttle body before the same being injected into the combustion chamber. With this, the spark plug generally receives a high-voltage charge from the ignition coil, creating a spark and igniting the air-fuel mixture.
A glow plug is known as an electrical heating device which is situated in each cylinder of the diesel engine. This ensures a reliable start in all the weather conditions especially in cold weather. A glow plug is required only during the ignition process, unlike a spark plug which functions continuously while you’re driving. It works by electrifying the heating element present in the engine, so it heats up and helps to reach the Self Ignition Temperature of diesel in fraction of seconds. In diesel engines the fuel is injected directly in to the combustion chamber where it mixes with the compressed air, and starts the combustion, even when the engine is cold.