Why Does the Abnormal Noise Disappear After Car Startup?
2 Answers
Car startup abnormal noise disappears because the vehicle has just been started and is in a cold state, where all mechanical components have not yet reached normal operating conditions. Below is relevant information about car abnormal noises: 1. Solution: A regular humming noise after reaching 40 km/h is due to tire issues. Starting from 40,000 kilometers of vehicle use, a regular humming sound may occur at around 40 km/h. You can try wheel balancing or four-wheel alignment. Additionally, rotating the four tires and swapping the inner and outer positions can solve the problem. 2. Fault Cause: The issue arises from uneven wear on the inner and outer sides of the tires. At the time, the tires had been used for about 15,000 km, with a humming sound occurring between 80-120 km/h.
I've encountered this issue before - a squeaking noise at startup that disappears when the engine warms up. My car's getting older, and these things happen frequently, usually due to loose or aged belts. During cold starts, when the engine runs stiffly, insufficient belt tension causes slippage and noise. Once the engine warms up, the belt expands from heat and tightens, naturally silencing the noise. Sometimes it's a small crack in the intake system gasket - you'll hear a hissing sound during valve operation that stops when temperature rises and closes the gap. Though temporary, such noises indicate component wear. When I inspected my belt and found small cracks, I knew it needed replacement. Similarly, bearings lacking lubrication make dry grinding noises until warmed oil seeps in. I recommend regular checks of belt tensioners and timing chains to avoid major repairs later.
