What is the cause of the hissing or compressed air sound that occurs when the brake pedal is pressed in a car? - Poe
When I press the brakes in a car, there is a sort of hissing, almost compressed air sound coming from the brake pedal. What causes that? - Quora
When I press the brakes in a car, there is a sort of hissing, almost compressed air sound coming from the brake pedal. What causes that? - Quora
![Does the power brake booster make a hissing or bearing noise until appling brakes which changes the pitch of noise? Does the power brake booster make a hissing or bearing noise until appling brakes which changes the pitch of noise?](https://www.justanswer.com/uploads/ebrock63/2009-07-14_203252_2009-07-14_142710.png)