Whooshing - airleak sound from brakes
2001 Ford Escape - there is a whooshing, air leaking sound when I take my foot off the brake. It's gotten louder over the past week. If I apply the brake the noise stops. Brakes are not mushy or spongy - still able to brake properly. Thinking it may be the vacuum, hoping it's not the Master Cylinder (especially as the brakes are working perfectly). Thank you for any assistance.