What Causes Regular Abnormal Engine Noises?
4 Answers
Engine regular abnormal noises are caused by drawbacks of direct fuel injection technology, operation of the carbon canister solenoid valve, and cold starts of the vehicle. Drawbacks of direct fuel injection technology: Direct fuel injection engines often produce louder noises because the fuel injection pressure in these engines is over ten times higher than that in conventional engines. The high-pressure injection from the fuel injector causes vibrations, which are particularly noticeable as a "ticking" sound during quiet conditions or slow driving. Operation of the carbon canister solenoid valve: The carbon canister solenoid valve opens when the engine starts, allowing the gasoline vapors adsorbed in the carbon canister, along with air, to enter the combustion chamber. This process not only reduces emissions but also lowers fuel consumption. During operation, this component can also produce a clear "ticking" sound. Cold starts of the vehicle: Many vehicle owners hear a "ticking" noise from the engine compartment during cold starts. This abnormal noise is actually caused by the fuel pump not being fully primed during the cold start.
Last time I encountered a strange ticking sound from the engine, and found it was caused by the belt system. When the tensioner pulley bearing wears out, it produces rhythmic knocking noises, especially noticeable during cold starts. A failing power steering pump or alternator bearing can also create rhythmic humming sounds, like steel balls rolling in an empty can. Another possibility is a loose timing chain, which produces metallic scraping sounds while driving - this needs immediate repair to avoid valve damage requiring major engine overhaul. I recommend first opening the hood to carefully locate the sound source. If it's in the belt area, use a flashlight to check for belt cracks. If unsure, visit a repair shop for stethoscope diagnosis - never ignore such abnormal noises.
From my experience, regular abnormal noises usually indicate issues with certain engine components during cyclic operation. Excessive piston-rod clearance produces a clanging sound at specific RPMs, while worn valve lifters create a ticking noise at idle. The knocking sound from damaged crankshaft bearings accelerates with throttle input. The last car I dealt with had abnormal noises caused by loose flywheel bolts, producing a clunking sound with every clutch engagement. Remember that sound frequency is crucial: valve noises can reach 2000 beats per minute, while piston sounds synchronize with crankshaft RPM. Engine temperature also affects diagnosis, with metallic sounds being most distinct during cold starts. I recommend recording the noise video as reference for technicians.
Hearing a regular abnormal noise while driving can indeed be unsettling. Last time I encountered a similar situation, it was due to a failed water pump bearing, which produced a periodic whining sound. This kind of noise changes with the engine RPM—at idle, it sounds like a ticking second hand, but when accelerating, it turns into a continuous buzzing. Power steering pump failure can also cause a rhythmic humming vibration, especially noticeable when turning the wheel. The most concerning issue is with the valve train, which sounds like a small hammer tapping on the engine. If left unrepaired for a long time, it can wear grooves into the camshaft. In such cases, I always pull over immediately, turn off the engine, and call for roadside assistance. Never attempt to drive to your destination—just an extra 10 kilometers could mean thousands more in repair costs.
