What Causes the Zizzing Sound During Car Idling?
2 Answers
Engine overheating, check the cooling system. More details about the zizzing sound during car idling are as follows: 1. Engine overheating: The engine makes a "squealing" sound, similar to steam or air escaping from the engine. Typically, after hearing this sound, the engine rapidly loses power. Possible issues include engine overheating—check the cooling system. Exhaust system blockage, vacuum tube leakage, or breakage. 2. Other issues: When pressing the accelerator deeply, you may notice sluggish acceleration, lack of power, and the engine making a hysterical sound. This is most likely to occur when the engine is hot or cold, or when it is low on oil. Causes for such problems can include issues with the air filter, spark plugs, ignition wires, gasoline, fuel filter, carburetor, or fuel pump.
My own old car used to make that annoying buzzing sound at idle too. Experience tells me it's most likely the belt system acting up, like a loose or worn alternator belt or AC compressor belt. When they rub, they tend to produce this kind of high-frequency noise. If the belt is aging or the tensioner pulley is faulty, the sound becomes especially harsh at idle when the engine RPM is low. It could also come from a vacuum hose leak, where any gap will let out that hissing air sound. I once fixed it myself by tightening the belt with a wrench, but ignoring it could lead to the belt snapping and causing the car to stall while driving—that’s seriously dangerous. I’d suggest getting the belts checked at a repair shop sooner rather than later to avoid bigger trouble.
