Diesel engine preheating system (Mazda Familia BG)

In a cold engine, the autoignition temperature is not reached by compression alone, so the engine requires preheating.

For this purpose, a glow plug is screwed into each combustion chamber. The plug consists of a housing and a pressed-in heat rod. When voltage is applied, the heat winding in the core heats up to a temperature of +850°C in a few seconds, due to which the pre-heating duration before starting rarely exceeds 10 seconds. When the pre-heating indicator lamp on the instrument panel goes out, the engine can be started.

To quickly warm up the engine, the preheater also works after the engine has started. The preheater duration is adjusted by the control unit depending on the coolant temperature. The control unit is located behind the center console under the air duct.

The pre-glow control unit receives engine temperature information from the coolant temperature sensor. Based on the received data, the control unit determines the pre-glow duration and the current value.