Hissing Noise From My Brake Pedal

[v_leesy2k1]

has any1 out there got any idea y i get a hissing sound from my brake peddal iv been told by a freind that its back pressure and not to worry bout it

but my mot is due end of month will my car fail due to this noise it is intermittant and more anoying than anything else

 

plz help

[marinabrid]

sounds like the prob we had last month and many more have had

its very possibly the seal inside the servo that has failed which causes a hiss that comes and goes. the fix though is expensive and long if it is the servo

i coulnt find a used one and had to buy new

[CM2007]

It sounds very viable that the servo is on it's way out. The hissing noise will be caused by an escape of the vacuum from the servo. You may be lucky enough that you have a vacuum leak elsewhere but the servo sounds the most likely cause. The servo assists the brakes by supplying a vacuum between the brake pedal and master cylinder which makes breaking easier,i.e. the vacuum does some of the work for you. The problem you face now is if you are still driving and it fails suddenly, the brake pedal will become very hard under braking and because you are used to applying the correct amount of pressure with your foot, if the assistance is removed, you will have to brake much harder which may catch you out causing an accident. I would get it checked ASAP.

 

Mike

[v_leesy2k1]

took my car for an mot i passed with flying coulors after the guy handed me my mot i told him bout the

hissing noise and he said he had noticed it he said it could be cause iv got to much brake fluid in my hedder tank

drain some off and it will stop

if it dont its just back pressure

what do u think ov that he blagging or what

[davgree]

took my car for an mot i passed with flying coulors after the guy handed me my mot i told him bout the

hissing noise and he said he had noticed it he said it could be cause iv got to much brake fluid in my hedder tank

drain some off and it will stop

if it dont its just back pressure

what do u think ov that he blagging or what

 

I notice he used the words "It could be" "or if not its" ...

 

I had this problem a couple of years ago with my Sharan, it was also the servo, seems to be a very comon problem, I drove it for about 10 months before I replaced it, the hissing got so loud I could not hear the radio!

 

As posted above though, it could fail and catch you out !