What is a critical safety practice before performing maintenance on an engine?

Turning off and cooling the engine is an essential safety practice before performing any maintenance on an engine. This step is critical because engines generate significant heat during operation, and touching a hot engine can lead to burns or injuries. Additionally, an operating engine poses risks such as unexpected movement or accidental activation, which can lead to serious injuries if a technician is working in close proximity. By ensuring that the engine is not only turned off but also allowed to cool down, the risk of accidents is greatly minimized, creating a safer environment for maintenance tasks to be conducted.

Increasing engine RPM, although related to engine operation, is not a practice that contributes to safety during maintenance. It can actually increase the risk of accidents or emissions exposure. Removing the air filter has no direct bearing on the safety of performing maintenance and might expose the engine to contaminants. Disconnecting the battery is important for preventing electrical shocks and ensuring safety while working on electrical components, but it is not the first step to take in the general maintenance process. Therefore, ensuring that the engine is off and cool is paramount for safety before any maintenance work begins.