What is the reason for the screeching sound when braking with a cold engine that disappears when the engine is warm?
2 Answers
The reasons for the screeching sound when braking with a cold engine that disappears when the engine is warm are: 1. The brake caliper does not return to its original position, causing abnormal noise due to friction between the brake pads and the brake disc; 2. Insufficient lubrication of the engine due to oil settling at the bottom when the engine is cold, resulting in abnormal noise. The maintenance methods for brakes are: 1. High-temperature protection to prevent corrosion of the brake system and avoid the brake pads sticking due to high temperatures; 2. Clean oil stains from the brake disc and brake drum components to maintain heat dissipation of the brake disc; 3. Regularly replace the brake fluid; 4. Regularly check the thickness of the brake pads or brake shoes. The function of the brakes is to reduce speed or stop the vehicle. Their working principle involves converting the kinetic energy of the moving vehicle into heat energy through friction between the brake pads and the brake drum, as well as between the tires and the ground, thereby slowing down or stopping the car.
The other day when I was driving, the cold morning start was unbearable with the brakes screeching loudly, but the noise disappeared after driving for a few minutes when they warmed up. This is mainly because there might be dew or moisture on the cold brake pads, causing a harsh friction sound, or slight rust spots making the surface uneven, which is more noticeable when the car is cold. After warming up, the friction improves, the moisture evaporates, and the noise goes away. I've encountered this situation many times over the years of driving, especially after parking in humid weather. I recommend parking in dry areas and avoiding damp grassy spots; lightly pressing the brakes a few times to warm them up before driving after rain can help alleviate the issue. Remember to clean the wheel hub area during regular car washes to prevent dust buildup. If the problem persists, it's best to check the brake pad thickness once a year if they show slight wear to ensure safety. Don’t worry too much—as long as the screeching isn’t constant, it’s not a major issue.
