A glow plug is a heating device used to aid starting of a diesel engine in cold weather). It is a pencil-shaped piece of metal with an electric heating element at the tip). Glow plugs are designed to heat incoming fuel and air to encourage efficient fuel combustion in a diesel engine. A glow plug system consists of either a single glow plug in the inlet manifold or one glow plug per cylinder). In older systems, the driver is required to manually activate the glow plug system and wait approximately 20 seconds before starting the engine. Newer systems automatically activate the glow plug(s) before the engine is started and have a quicker warm-up time).
Glow plugs resemble short metal pencils, and the heating element is fitted into their tip. Glow plug filaments must be made of certain materials, such as platinum and iridium, that resist oxidation and high temperature). Glow plugs are not used in gasoline vehicles because they do not produce enough heat for the mixture in a diesel combustion chamber. Cylinder compression is stronger in diesel engines, so they require more heat to ignite.
Symptoms of a bad diesel glow plug include a rough idle, trouble starting the car, and black smoke coming out from the exhaust pipe. A faulty glow plug can also turn on the check engine light on the dashboard and store the glow plug related error codes.
