What Causes Abnormal Noises During Cold Car Startup?
2 Answers
Cold start abnormal noises may occur due to the following reasons: 1. Hydraulic lifters: Low oil pressure or wear in the hydraulic lifters can cause air to enter, resulting in abnormal sounds. The air needs to be purged. 2. Valve clearance: Wear in the valve rocker arms can lead to excessive valve clearance. 3. Dirty throttle body: Accumulation of sludge and carbon deposits can cause the throttle body to become dirty. In this case, the throttle body needs to be cleaned. 4. Carbon canister purge valve operation sound: This is a normal sound, and the vehicle can continue to be used. If the noise is excessively loud, it is recommended to have it checked at a 4S shop.
I am a car enthusiast and often discuss such issues. During cold starts, the most common cause of abnormal noise is slack or aging in the belt system, such as the alternator belt or air conditioning belt. In low temperatures, the rubber hardens and causes friction, resulting in a squeaking sound. Worn bearings in the belt tensioner pulley can also produce similar noises. Another possibility is timing chain wear, especially in high-mileage vehicles, where a rhythmic clicking sound occurs during startup due to increased chain slack. If the hydraulic lifters have insufficient oil supply or slow oil pressure buildup, metal components may collide, creating a ticking sound. A simple initial check is recommended: inspect the belts for cracks and ensure the oil level is adequate. Visit a professional shop early for diagnosis to prevent minor issues from escalating into engine damage. In winter, warming up the engine for about 30 seconds helps with lubrication and reduces the risk of abnormal noises. Regular oil and belt changes are key preventive measures.
