What causes the rattling sound in the VVT variable timing pulley?

[AlexanderAnn]

When the VVT variable timing pulley produces abnormal noises during car idling or low-speed operation, it is due to excessive clearance between the piston and cylinder wall, overly tight piston pin assembly, overly tight connecting rod bearing assembly, or wear on the camshaft profile. This can lead to issues such as unstable engine idling, poor acceleration, increased fuel consumption, and may also cause abnormal engine noises, typically metallic screeching or whistling sounds. VVT (Variable Valve Timing) technology is used in automotive piston engines. Under specific conditions, it adjusts the intake valve timing by advancing or delaying the intake valve angle, thereby regulating intake/exhaust volume and valve overlap angle. This enhances intake impulse and efficiency, improving engine power, torque, and other performance aspects.