What causes the ticking sound at idle that disappears when accelerating?
4 Answers
Ticking sound at idle that disappears when accelerating is typically caused by a faulty carbon canister purge valve, which should be replaced. The function of the carbon canister purge valve is to open the solenoid valve between the carbon canister and the intake manifold after the engine starts, allowing the adsorbed gasoline vapors in the carbon canister to enter the combustion chamber along with air for burning, thereby reducing emissions and fuel consumption. Below is relevant information about engine idling: 1. If the engine runs at idle for an extended period, the throttle opening will be very small, and the fuel injector will spray highly concentrated fuel to maintain engine operation. Therefore, idling itself is more likely to cause carbon buildup compared to driving or highway speeds. Prolonged idling will inevitably lead to more severe carbon buildup in the engine. 2. During engine idling, the temperature and pressure inside the cylinders are relatively low, prolonging the preparation time for fuel ignition. Additionally, the sealing performance of the cylinders decreases at this time, making it easier to produce knocking sounds and shortening the engine's service life.
I've been researching car abnormal noises, and the ticking sound at idle that disappears when accelerating is quite common. One of the reasons could be insufficient oil or wear in the hydraulic lifters. At idle, the oil pressure is low, preventing the lifters from working fully, creating gaps that cause ticking sounds; when accelerating, the increased oil pressure allows the lifters to function normally, and the noise disappears. Another possibility is a loose timing chain, which rattles at idle but tightens up at higher RPMs, making the noise go away. First, check the oil dipstick to see if the oil level is low or if the oil is dirty. If it's low, top it up, and if it's dirty, try changing to fresh oil. If the noise persists, it might be an issue with the lifters or the chain itself, requiring replacement or repair. Don't ignore this small problem, as it could indicate internal engine wear, and delaying repairs might lead to performance degradation or damage. Early detection and repair are key to maintaining vehicle health.
My car had this issue before. It made a rattling sound at idle, but the noise disappeared when accelerating. That time, the inspection found that the drive belt was loose. At low idle speed, the loose belt wobbled and made abnormal noises; at higher speeds when accelerating, the belt tightened and the noise vanished. Simply going to a repair shop to tighten it solved the problem, but it could also be a faulty alternator pulley or AC pump. I suggest checking the belt's tightness by hand first; if there are cracks, replace it. That time, I solved it with a small cost, but ignoring it could lead to the belt breaking and a dangerous breakdown. Regular maintenance, including belt inspection, is key to prevention.
The ticking noise at idle that disappears when accelerating is often caused by component gaps, such as those in the valve lifters, which produce noticeable abnormal sounds at idle but reduce or get masked when accelerating. Although the sound is minor, it indicates wear and tear. Ignoring it may worsen engine damage and affect safety. First, check the engine oil to ensure it is sufficient and clean—top it up if low or replace it if dirty. If the noise persists, immediately seek diagnosis and repair from a professional shop to prevent minor issues from escalating. Ensuring safe driving is the top priority.
