Q: I have a 2000 F-150 the makes a whistling sound when applying or releasing the brake pedal. It sounds like air being let out of a

asked by on April 17, 2017

When i apply or release the brakes coming to a full stop or leaving a full stop i hear a whistling sound, like air being let out of a balloon. What's causing this?

My car has 158000 miles.
My car has an automatic transmission.

The brake booster uses engine vacuum to provide power assist when you step on the brake pedal. A component within the booster, such as the valve, and/or the external check valve or vacuum lines is probably leaking. The leak of rushing air creates the noise. That is the first possibility that should be looked at. Inasmuch as it is a strong possibility, if you desire you can request a booster inspection and if indeed the fault lies in that "system" the mechanic, once done with the diagnosis, can commence the repair right away. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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