Here's a breakdown of why:
* Worn brake pads: When your brake pads wear down to the metal backing plates, they grind against the rotors (the metal discs your pads squeeze against). This creates a high-pitched grinding noise. Applying the brakes presses the pads firmly against the rotors, sometimes temporarily silencing the noise (though it could also be making things worse by further damaging the rotors).
* Damaged rotors: Severely worn or damaged rotors can also produce a grinding noise, even with relatively new brake pads. The rough surface of the rotor will scrape against the pads.
* Other possibilities (less likely): While less probable given the symptom of the noise stopping with braking, other issues could include something caught in the brake caliper or a problem with the wheel bearing (though wheel bearing noise usually changes pitch with speed).
What you should do:
* Do NOT continue driving. Driving with severely worn brake pads is extremely dangerous. You risk losing braking power completely.
* Have your vehicle inspected by a mechanic immediately. They can diagnose the exact problem and perform the necessary repairs. Delaying this can lead to more extensive and costly damage.
Ignoring this noise could lead to a dangerous situation, so getting it checked is crucial for your safety.
