What Causes the Abnormal Noise During Cold Start That Disappears After Warming Up?
3 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.
My old car had a similar issue before. There was always a rattling noise when starting it in the morning, which would disappear after driving for a few minutes when the engine warmed up. The mechanic said it was due to aging drive belts that would harden and slip in cold weather. It could be caused by a loose tensioner or worn timing chain, with larger gaps between components when cold. I delayed fixing it for a while, and eventually, the belt snapped during one startup, costing me much more to repair. The experience taught me that such noises should prompt immediate inspection of belt tension and condition. Now that the car is running normally, I feel much more at ease, and I always check the belts and pulleys during routine maintenance. If you're not confident in your DIY skills, it's best not to tamper with components under the hood—leave it to professionals to prevent minor issues from becoming major problems.
