Red Seal Heavy Duty Equipment Technician Practice Exam

What is one effect of excessive idling on a diesel engine?

1. Reduced emissions

2. Improved engine lubrication

3. Increased fuel consumption

4. Enhanced performance

The correct answer is: Increased fuel consumption

Excessive idling of a diesel engine leads to increased fuel consumption due to the engine running longer than necessary without any productive work being performed. When the engine idles, fuel continues to be injected into the combustion chamber, but the energy generated is not being used for propulsion, resulting in wasted fuel and lower overall efficiency. Additionally, prolonged idling can create a situation where the engine does not reach optimal operating temperatures, which can negatively impact combustion efficiency. This contributes further to the excessive use of fuel during idle periods. Understanding this effect highlights the importance of managing idle time to promote better fuel economy and reduce operational costs. The other options do not reflect the impact of excessive idling. For example, while some may think idling could reduce emissions, this is only true in specific scenarios where the engine's emissions system is designed to handle it; generally, it leads to the opposite effect. Similarly, idling does not improve lubrication; in fact, it can lead to oil degradation over time. Lastly, performance is typically diminished rather than enhanced during idling, as the engine is not operating under load.