What Does Engine Knocking Sound Like?
4 Answers
Knocking typically occurs when the throttle is fully open in high gear, manifesting as a metallic tapping sound from the engine. Knocking is an abnormal combustion phenomenon where pressure irregularities occur in the combustion chamber. Specifically, during flame propagation in the combustion chamber, unburned mixture gases far from the spark plug are compressed by the expanding burned mixture gases, causing localized mixture gases to auto-ignite prematurely before the normal flame front, forming multiple flame cores. The phenomenon where flame propagation speed and flame front shape change abruptly is called detonation, and the external reaction produced is knocking, which generates a metallic tapping sound inside the cylinder. Prolonged engine knocking can easily lead to issues such as piston sintering and piston ring breakage, accelerating the wear and tear of engine components.
The sound of engine knocking is really noticeable, like a tiny hammer constantly tapping metal under the hood, especially when you stomp on the accelerator to speed up. I've driven many cars, and this noise sounds like 'pinging' or 'rattling' abnormal sounds, sometimes mixed with slight popping noises. The reason is often insufficient fuel octane rating or improperly adjusted ignition timing, causing the air-fuel mixture to self-ignite prematurely. Having this sound for a long time isn't good—pistons or cylinder walls may wear out faster. I recommend using the recommended high-octane gasoline, regularly checking spark plugs and timing belts, and avoiding aggressive driving under high load.
The first time I heard engine knocking, it really scared me. The sound was like a bunch of small steel balls jumping inside the engine, especially when climbing hills or accelerating to overtake, making 'clunking' impact noises. Later I learned this is usually caused by using low-quality fuel or abnormal combustion due to engine overheating. If it persists, it can cause significant damage to internal engine components. Now I always choose high-quality fuel, listen carefully to my car's sounds, and slow down immediately if anything seems wrong before taking it to the repair shop to adjust the ignition system, preventing small issues from becoming major problems.
The sound of engine knocking is quite strange, like pieces of metal clanging against each other, especially noticeable when accelerating, somewhat resembling a light 'crackling' noise. I've encountered this during my daily commute, usually caused by fuel issues or minor ignition system problems. To prevent it, consistently using the correct octane-rated gasoline and regular maintenance to clean carbon deposits can significantly reduce the risk.
