What Causes the Whistling Sound in the Engine?

[MatthewLee]

Engine whistling sound can be attributed to the following reasons: Normal phenomenon: The turbocharger operates by exhaust gas propulsion. At low engine speeds, the turbo cannot be driven and remains inactive, hence no sound. Typically, the turbo starts working above 2000 RPM. During uphill driving, lower gears with higher RPMs, or when revving the engine without load, the increased exhaust gas flow activates the turbo, resulting in the sound, which is normal. Exhaust valve leakage: Caused by poor sealing of the engine's exhaust valves. Throttle body leakage: In diesel engines, this may be due to the Exhaust Gas Recirculation (EGR) valve; in gasoline engines, it's often caused by poor sealing of the throttle body. Exhaust pipe weld failure: Poor sealing or cracked welds in the exhaust pipe.