Red Seal Agricultural Equipment Technician Practice Exam

What is one common method of starting a diesel engine?

1. Using a spark plug

2. Cranking the engine manually

3. Using a glow plug to preheat the combustion chamber

4. Using high-pressure air to ignite fuel

The correct answer is: Using a glow plug to preheat the combustion chamber

Using a glow plug to preheat the combustion chamber is a standard and effective method for starting a diesel engine. Diesel engines operate on the principle of compression ignition, where air is compressed to a high pressure and temperature, causing the fuel to ignite spontaneously when injected. However, in colder conditions, the air temperature in the combustion chamber may not reach the necessary level for the fuel to ignite immediately upon injection. Glow plugs are electrically heated devices that are inserted into the combustion chamber. When activated, they provide the additional heat needed to raise the temperature of the air, facilitating the ignition of the diesel fuel when it is injected. This is especially important in cold weather or when the engine has not been run for an extended period, as it helps to ensure reliable starting and efficient combustion. Other methods of starting diesel engines, such as using spark plugs, are not applicable as diesel engines do not use spark ignition, but rather compression ignition. Manually cranking the engine can be used in specific situations but is largely outdated and not practical in modern applications. Using high-pressure air to ignite fuel, while a method employed in some specialized engines (like in some air-start systems), is not the common method for everyday diesel engines. Therefore, utilizing glow plugs remains the most