when I step on the brakes it sounds like there is air coming out what does that on 2001 Volvo V70 XC

it happens everytime I get in the car and back out to the main rd but after driving for about 5 mins the sound goes away

by in Naugatuck, CT on August 19, 2013
2 answers
ANSWER by on August 19, 2013
SEE PREVIOUS POST
ANSWER by on August 19, 2013
THIS IS CAUSED BY THE BRAKE BOOSTER HAVING AN INTERNAL DIAPHRAM VACUME LEAK. CAUSING BRAKE BOOSTER VACUME PRESSURE TO ESCAPE WITCH CAN BE HEARD JUST OBOVE BRAKE PEDAL. .