Why do diesel engines need glow plugs?

Reduce smoke emissions
Intake air heating
Reduce engine noise and vibration
Improving driving performance in cold environments

Warm up phase

The preheating system provides additional heat for a cold start. Before the engine starts, voltage is applied to the end of the glow plug, and the current flows through the heating coil inside the glow plug, thus heating rapidly.The heat energy is transferred to the protective shell to make it glow and heat.
The time required to obtain sufficient temperature for stable combustion varies with different engine designs.

Post heating stage

After start-up, the glow plug will heat up intermittently to reduce the white smoke or blue smoke, and eliminate the starting problem atlowtemperature.The post heating stage depends on the temperature of theengine, and thelow temperature diesel engine will produce more noise and pollution emissions.