What are the reasons for brakes making abnormal noises, failing, and then returning to normal?
2 Answers
The reasons for brakes making abnormal noises, failing, and then returning to normal are: 1. Lack of necessary maintenance on the brake system, excessive impurities in the brake master cylinder, poor sealing, failure of the vacuum booster pump, or dirty brake fluid; 2. Mechanical failure due to improper operation; 3. Severe overloading of the vehicle, which increases the vehicle's inertia under the effect of gravitational acceleration, directly leading to brake failure. The causes of brake failure include: 1. Impurities in the brake master cylinder and poor sealing; 2. Failure of the vacuum booster pump; 3. Dirty brake fluid; 4. Leakage in the brake master cylinder or wheel cylinder; 5. Leakage in the air reservoir or pipeline connections; 6. Severe overloading; 7. Carbonization of the brake drum; 8. Insufficient brake fluid in the brake master cylinder; 9. Wear of the brake master cylinder piston.
Once when I was driving downhill and continuously applying the brakes, I suddenly heard a sharp metallic noise, and the brake pedal felt spongy and couldn't be pressed all the way down, which scared me into releasing it immediately. After a while, when I tried again, it was back to normal. Upon inspection at the repair shop, it was found that the brake fluid hadn't been changed for three years and its water content exceeded 5%. Under high temperatures, the water in the fluid turned into vapor bubbles, causing vapor lock in the brake lines. The mechanic also mentioned that the surface of the brake discs on older cars might develop wave-like patterns from wear, leading to poor contact with the brake pads and causing unusual noises. This issue is particularly prone to occur in rainy weather or after repeated hard braking. The best solution is to regularly change the brake fluid and check the flatness of the brake discs.
