What is the reason for the metal friction sound when releasing the accelerator?
4 Answers
It may be due to noise from the engine timing chain or a malfunction in the timing sprocket. Below is relevant information about the engine: Introduction: An engine (Engine) is a machine capable of converting other forms of energy into mechanical energy, including internal combustion engines (reciprocating piston engines), external combustion engines (such as Stirling engines, steam engines, etc.), jet engines, electric motors, etc. For example, internal combustion engines typically convert chemical energy into mechanical energy. Expansion: The term engine can refer to both the power generation device and the entire machine including the power unit (e.g., gasoline engines, aircraft engines).
I've been driving for several years, and sometimes there's a metallic friction noise when I release the accelerator, which is really annoying. The most common cause could be excessive wear of the brake pads. When the brake caliper doesn't fully retract, it's easy to produce friction noise when decelerating by releasing the accelerator. Small stones stuck between the brake discs can also cause similar noises. Loose or cracked exhaust pipe joints are also quite common, especially in older cars, as vibrations in the exhaust system can produce metallic friction sounds. Additionally, loose or severely worn components in the suspension system, such as ball joints and control arms, can also make noise when the force changes. Once, my car had this issue, and after inspection, it was found that the rear suspension bushings were damaged—replacing them fixed the problem. Don't ignore such noises because if it's a brake system issue, delaying repairs could lead to an accident. It's recommended to stop at a safe place immediately upon hearing the noise, quickly check around the wheels, and if there's no obvious abnormality, go to a professional repair shop for diagnosis as soon as possible. The repair cost is much cheaper than a major overhaul.
As a car enthusiast, I often tinker with my car. The metallic friction sound when releasing the throttle can range from minor to serious. Key troubleshooting points are the braking system: if the brake pads are too thin or the caliper doesn't retract properly, it may cause friction noise when releasing the throttle. Another possibility is loose exhaust pipe brackets, especially producing 'creaking' sounds during engine load changes. Worn or cracked suspension control arms and bushings may also cause metallic friction. You can perform preliminary diagnostics yourself: gently press the accelerator and brakes on a safe road to compare sound changes; if the noise is louder during deceleration, it's likely a brake issue. Use a jack to lift the car and check for loose suspension components underneath. If unsure, take it to a shop for inspection as soon as possible - technicians can use professional tools to identify CV joint or driveshaft issues. Safety first, address problems early to prevent potential hazards from escalating.
Decades of driving experience have taught me that metallic friction noises when releasing the throttle are mostly brake or suspension issues. Worn brake pads make a rustling sound, and loose exhaust pipes vibrating can also cause noise. Aging suspension joints often produce noises in such situations. I remember my old Jeep used to make such sounds frequently, which were resolved after replacing the suspension ball joints. Regular maintenance can prevent these issues.
