Technical Venting Noise from Braking system

[Rosso187]

Hi All,
Took my Bravo T150 for its MoT today and it passed. However, on driving it home I noticed that when depressing the brake pedal their is a sound like air being vented coming from the passengers footwell area? It does it whilst driving or stationery and with engine running or off. Anybody have any idea what is causing this?
Had the car 3 years and it has never made this noise before.


Thanks in advance,


Stuart.

 

[F123C]

The brake servo is located on the passenger side, footwell area and can make a slight noise as described when the brake pedal is operated (can'td remember if its when the pedal is pressed or released? Brain tired/its late!)
There's usually a small foam filter around the brake pushrod under a rubber cover to stifle the sound. When you say the noise is there with the engine off, have you tried pressing the brake pedal several times (6+ times and the pedal will get harder as the remaining vacuum is used up) and see if the noise disappears until you start the engine again. If this is what happens it sounds like a brake servo problem, strange it only seems to have happpened since the MOT test?
A quick check on the servo is:- switch off engine,press brake pedal 6-8 times, pedal should feel firmer and higher, hold pedal down and start engine, pedal should sink slowly to a normal height. If this happens servo is probably ok. I wonder if the servo non-return valve is sticking/faulty? Do the brakes respond ok to normal pedal pressure or do you have to press harder,might mean a trip to a garage/mechanic to check it out!

Al.