Small electric heaters called _______, are placed in the combustion chambers of some diesel engines to help with cold starts

• A. Glow-plugs
• B. Spark plugs
• C. Pre-heat coils
• D. Ignition heaters

Answer: (A)

Diesel engines rely on compression heating to ignite fuel, and in cold weather there isn’t enough heat in the cylinder for reliable starting. Glow plugs are electric heaters placed in the combustion chamber that preheat the cylinder air (and the injected diesel) to a high temperature, making ignition possible when starting. This is why they’re used to aid cold starts. Spark plugs are for gasoline engines and ignite a premixed charge with a spark, which isn’t how diesels start. Pre-heat coils and ignition heaters aren’t the everyday term for this device, while glow plugs are the recognized component that provides the necessary heat for cold-start ignition.