What to Do When Brakes Squeak at Low Speed with Cold Engine but Disappear When Warm?
2 Answers
The reason for brakes squeaking at low speed with a cold engine but disappearing when warm is due to the brake caliper not retracting properly and oil sedimentation when cold. Below is relevant information about cold-engine braking: Brake Caliper Not Retracting: Even when not pressing the brake pedal, you may still feel significant resistance from the car. In severe cases, abnormal noises may occur or even wheel lock-up. This phenomenon is generally caused by not changing the brake fluid for an extended period, leading to internal rust in the brake caliper, or poor precision of the caliper causing the piston not to retract fully. It can also be due to blocked brake caliper pipelines, resulting in abnormal noises from friction between the brake pads and brake disc. Oil Sedimentation When Cold: When the engine is cold, oil sedimentation occurs at the bottom. Sedimentation is a normal phenomenon, with additives generally settling at the bottom. Lubricants contain additives, and in some cases, these additives may precipitate out, causing abnormal noises due to insufficient engine lubrication.
I've encountered this issue while driving. When starting the car cold and gently applying the brakes, there's always a sharp screeching sound, but the noise disappears after driving for a while when the car warms up. It's quite annoying. This situation usually occurs because the brake pads have some rust or dust particles when cold, causing high-frequency noise during friction. When the temperature rises, the rust melts or the surface becomes smooth, and the sound naturally disappears. First of all, don't worry—it's not a major problem. I've dealt with it myself. First, check if the brake pads have enough thickness. If they're nearly worn out, replace them with new ones immediately. If the pads are still thick, clean the brake discs by blowing off dust with high-pressure air or spraying some brake cleaner. If that doesn't work, take it to a 4S shop and let the mechanics check if the brake calipers and guide pins are sticking. Safety comes first—don't delay too long to avoid affecting braking performance, especially when roads are slippery in rainy weather. Additionally, pay more attention to brake system maintenance during regular servicing. Choosing OEM or high-quality brand pads when replacing them can prevent such issues.
