What Causes Abnormal Noise When Starting the Car and Braking?

[MacLillian]

The reasons for abnormal noise when starting the car and braking are: 1. Brake run-in; 2. Normal activation of the ABS system; 3. Metal hard spots on the brake pads; 4. Severe wear of the brake disc; 5. Improper installation of the brake pads; 6. Sharp noise when braking in reverse; 7. Small stones or a water film between the brake disc and pads; 8. Foreign objects in the braking system; 9. Severe wear of the brake pads. The function of the brake is to reduce speed or stop the vehicle. Its working principle is: by using the friction between the brake pads and the brake drum, as well as between the tires and the ground, the kinetic energy of the moving vehicle is converted into heat energy after friction, thereby slowing down or stopping the car.

[ChristopherAnn]

My experience tells me that when there is abnormal noise from the brakes during car startup, it is mainly due to rust or dust accumulation on the brake discs or pads. Especially after rainy days, if the car is parked for a while, an oxidation layer forms on the surface of the brake discs, causing a squeaking sound when you first apply the brakes, which can sound quite alarming. This situation is most common in humid weather, and if the noise disappears after driving for a short while, there’s no need to worry. Another possibility is that the brake pads are worn too thin, causing the metal backing to grind against the brake disc, producing a sharp noise. Over time, this can lead to deformation of the disc and pads. I’ve encountered this a few times while driving. First, check the remaining thickness of the brake pads and try cleaning off the rust or dust with compressed air. If the problem persists, don’t delay—take it to a repair shop immediately to check if the calipers are sticking, to avoid serious safety risks. These minor issues may seem simple, but ignoring them could lead to brake failure, especially during high-speed driving. Regularly washing your car to keep the brake system clean can help reduce this risk.

[LauraRose]

As someone who enjoys car repairs, I believe that squeaky brakes when starting the car are mostly caused by foreign objects or rust. When parked outdoors or in dusty areas, small stones or sand can get stuck between the brake pads and rotors, causing a squeaking sound when braking. I've tried driving at low speed and gently applying the brakes a few times to let friction clear out the debris, which works fairly well. Newly replaced brake pads may also produce this sound initially, which is part of the normal break-in period. A deeper issue could be insufficient lubrication on the brake pins, causing excessive friction between components. I've personally applied specialized grease to fix this, but it's crucial to use professional-grade grease—otherwise, you risk damaging parts and making the problem worse. If the noise persists, I remove the wheel to inspect for uneven wear or warping of the pads and rotors. For more complex issues like low brake fluid or caliper malfunctions, it's best to seek professional help rather than attempting DIY fixes. Taking these preventive measures can help avoid costly repairs down the road.

[RyderLee]

Years of driving experience have taught me that unusual noises when starting or braking should never be taken lightly. It's common for components to expand and contract at different rates due to thermal changes, causing sounds, especially when starting the car in cold weather. However, if the noise is sharp and persistent, it could indicate that the caliper hasn't retracted properly, causing the brake pads to constantly rub against the disc. This leads to overheating and reduced performance, and in severe cases, the wheel may become excessively hot or even melt. I once ignored such a warning and nearly had an accident due to delayed braking. Another issue could be a compromised seal in the braking system, allowing air to enter and causing abnormal responses. These signals warn of potential dangers. If you hear unusual noises, stop immediately to check for excessive heat around the wheel rim or any burning smell. Don't take chances—seek professional diagnosis and repair to ensure driving safety.