What Causes the Abnormal Noise During Cold Start That Disappears After Warming Up?
2 Answers
Generally, the main sources of abnormal noise during cold start include poor sealing of engine valves, inadequate lubrication; excessively tight belts or bearing noise. If the abnormal noise persists after the engine has warmed up, it is recommended that the owner promptly take the vehicle to a repair shop for inspection to identify the specific cause. More details are as follows: 1. Normal abnormal noise: When a car is parked for more than a day, the engine's lubricating oil almost completely flows back into the oil pan. During a cold start, the oil pump cannot immediately establish oil pressure, and an oil film cannot form between components, especially in the cylinder head and internal valves. Without lubrication during a cold start, whether it's hydraulic lifters or mechanical rocker arms, there will be some valve clearance, resulting in a ticking noise. After the engine runs for a while, oil pressure is established, an oil film forms, and the oil temperature rises, the ticking noise disappears as the engine operates normally. This is a normal situation, and the owner need not worry. 2. Oil quality issues: Sometimes, they can also cause the engine to produce a ticking noise. Therefore, a ticking noise during a cold start is not a fault. However, if such abnormal noise occurs when the engine is warm, the owner should pay attention.
There is abnormal noise during cold starts which disappears after the engine warms up. I guess it might be a common issue. Usually, it's a problem with the belt. When the car cools down, the belt material becomes harder and more brittle, prone to looseness or aging, causing a squeaking sound when rubbing against the pulley. After warming up, the belt expands normally and the noise stops. It could also be an issue with the timing chain tensioner; insufficient oil pressure when cold makes it operate less smoothly, resulting in a clicking sound. Other components like the water pump bearing or air conditioning compressor may also contract more noticeably at low temperatures. I recommend checking the belt for cracks or looseness as soon as possible. Ignoring it could lead to belt breakage, affecting battery charging or steering. Visit a reputable repair shop for a comprehensive diagnosis. Safety first—don't delay and let the problem worsen.
