What is a common indicator of engine knock?

A common indicator of engine knock is the presence of abnormal noises from the engine. Engine knock, also known as detonation, occurs when the air-fuel mixture in a cylinder ignites at the wrong time or too early, causing a significant disturbance in the normal combustion cycle. This results in a knocking or pinging sound as the shock waves from the spontaneous combustion hit the cylinder walls.

Abnormal noises can vary in character but are typically perceived as metallic, sharp, or more aggressive than the usual engine sounds. Recognizing these noises is crucial because prolonged engine knock can lead to engine damage, including issues like burnt pistons or damaged cylinder heads. Monitoring for these indicators allows for early detection and corrective action to be taken to prevent serious engine damage.

In contrast, smooth engine operation, consistent power delivery, and high fuel economy are signs of a well-functioning engine and do not indicate any issues with engine knock.