What are the causes of engine abnormal noise?
2 Answers
Causes of abnormal engine noise in automobiles include aging or loosening of engine mounts, piston slap, misfire-induced noise, and excessive carbon buildup in the throttle body or fuel injectors. Below are detailed explanations and corresponding solutions: Aging or loosening of engine mounts: Engine mounts, also known as engine cushions or brackets, are typically installed between the engine and the vehicle body, connecting the two and securing the engine in place. Their most important function is to provide vibration damping and shock absorption. Once the engine mounts age or become loose, engine vibrations will produce abnormal noises, necessitating replacement of the mounts. Piston slap: This occurs when the piston tilts and the direction of lateral pressure changes, causing the contact surface between the piston and cylinder to shift from the secondary thrust side to the primary thrust side, resulting in lateral oscillation. Consequently, the engine periodically produces a knocking sound as the piston strikes the cylinder wall. Replacing the engine oil can resolve this issue. Excessive carbon buildup in the throttle body or fuel injectors: If carbon deposits in the engine are severe, leading to symptoms such as rough idling, increased fuel consumption, and reduced power, the engine may produce abnormal noises. Cleaning the engine carbon deposits, servicing the throttle body, and replacing the gaskets and spark plugs can address this problem. Misfire-induced noise: Engine misfire primarily refers to one or more cylinders not functioning properly, typically characterized by noticeable gaps in the exhaust gas flow, severe shaking of the exhaust pipe, and distinct "popping" or thumping sounds from the engine. This phenomenon is often related to faulty ignition coils, so inspecting and repairing the ignition coils is necessary.
I've found that most engine abnormal noises are caused by internal mechanical wear. For instance, loose piston rings produce knocking sounds, damaged connecting rod bearings result in continuous metal friction noises, and excessive valve clearance may create a ticking sound. These issues often occur in high-mileage vehicles or due to insufficient lubrication where oil fails to protect components. If you hear a rattling noise, it might involve timing chain or belt slippage, which could lead to complete engine stall. I've handled multiple cases where neglect not only caused drastic fuel consumption increases but also potentially total engine failure. It's cost-effective and reassuring to promptly visit a reliable workshop for diagnostic scanning. The key is to frequently check oil levels, change oil regularly, and address issues before noises escalate.
