Why does the brake squeal at low speed when the car is cold but disappears when the car is warm?
3 Answers
The reason for the brake squealing at low speed when the car is cold but disappearing when the car is warm is due to the brake caliper not retracting properly and oil sedimentation when the car is cold. Below are the related explanations for cold car braking: Brake caliper not retracting: Even when the brake pedal is not pressed, there is still a noticeable resistance felt in the car, and in severe cases, abnormal noises may occur or even the wheels may lock up. The cause of this phenomenon is usually not changing the brake oil for a long time, leading to internal rust in the brake caliper, or poor precision of the caliper, causing the piston to not retract properly. It can also be due to blocked brake caliper pipelines, resulting in abnormal noises from the friction between the brake pads and the brake disc. Oil sedimentation when the car is cold: When the car is cold, the oil settles to the bottom, which is a normal phenomenon. The sediment at the bottom is generally additives. Lubricating oils contain additives, and in some cases, these additives may precipitate out, causing abnormal noises due to insufficient engine lubrication.
I've been driving for over ten years, and it's very common to hear squeaky brakes when starting the car cold, which disappears after the car warms up, especially in humid or cold weather. There are several main reasons for this: first, the brake disc surface accumulates dew or slight rust overnight, causing high-frequency noise from friction during cold starts; second, the brake pad material is harder or unevenly worn at low temperatures, leading to vibration and squealing; third, after the car warms up, the temperature rises, the friction coefficient increases, impurities are burned off, and the noise naturally disappears. This isn't necessarily a major fault, but don't ignore it, as it may indicate that the brake pads are nearing the end of their lifespan. If not addressed promptly, it could accelerate brake disc wear or even affect braking performance. It's recommended to have a technician check the brake pad thickness and cleanliness during the next maintenance service, and develop the habit of avoiding prolonged water accumulation when parking.
As someone who frequently works on cars, the issue of squeaky brakes at low speeds when the car is cold, which disappears when the car warms up, is often caused by external factors. A common reason is the formation of a water film or minor rust spots on the brake disc surface in humid environments, creating a high-pitched noise during initial friction at low temperatures. Another possibility is hardened or contaminated edges of the brake pads, which are unstable when cold and prone to vibration. Once heat builds up, the disc surface dries, and friction becomes smoother, eliminating the noise. This issue is generally not urgent but serves as a reminder to check the brake pad wear. If the thickness is less than 1/4, replacement is necessary. Parking in dry areas and avoiding exposure to rain can reduce occurrences. Regular maintenance is key to prevention, ensuring the calipers move freely. In short, don’t hesitate to investigate minor issues yourself, but for more complex problems, seeking a professional shop is advisable for peace of mind.
