What is the reason for the hissing sound when stepping on the brake?
2 Answers
The reason for the hissing sound when stepping on the brake is that there is air in the brake system pipeline. After this situation occurs, the air in the brake system pipeline should be bled out. The brake system is an important system in a car, as it relates to the driving stability and safety of the vehicle. The main components of the brake system include: vacuum booster pump, master cylinder, wheel cylinder, brake pads, and brake discs. The principle of the brake system is to generate enormous friction to convert the vehicle's kinetic energy into heat energy. The brake system relies on brake pads (disc type) or brake shoes (drum type) to perform the braking function, so it is necessary to regularly check the thickness of the brake pads or brake shoes.
Recently, my car's brakes have been making a squealing noise, most likely because the brake pads are almost worn out. The small metal tab inside starts touching the brake disc, causing that screeching sound to remind you it's time for a replacement. Also, during my last maintenance check, I noticed severe rust on the brake discs, especially after leaving the car parked for several days—the rust rubbing against the brake pads creates this noise. If the noise persists right after installing new brake pads, it might be because the discs and pads haven't properly bedded in yet; it usually goes away after driving a few hundred kilometers. Some brake pads with high metal content can also keep making noise continuously. More importantly, check if a small stone is stuck in there—once after a car wash, I heard an especially sharp noise, and upon inspection, found a tiny stone lodged in the gap. I recommend not ignoring such sounds and getting your brake system checked as soon as possible.
