air hissing noise coming from brake pedal

Leaking diaphragm in the power booster.

caradiodoc

The brake booster will need to be replaced. Thanks for using 2Carpros.com

fanx will my brakes fail on me,and can i do the repair myself if so is it easy 2 do or not? and do u no how much a diaphragm will cost fanx

hi is this dangerous like will my brakes fail,i put my hand around the rubber at the back ov the pedal and it stopped hissing so is it still that problem or not? also i pushed n pulled my brake pedal and the hissing stopped wen i pulled and pushed. . .is it dear to replce the booster and can i do it myself thanx

You should be able to do it yourself but on some trucks it can be hard to get to some of the nuts. There will be two nuts holding the master cylinder to the booster and typically four nuts under the dash holding the booster to the firewall. Pay close attention to how the push rod is attached to the brake pedal and if the brake light switch is attached there too.

It might be easier to get a used booster from a salvage yard first so you can look at it to see how it is mounted.

caradiodoc

You will still have brakes but the pedal might be hard to press. Only the power assist function will be lost.

caradiodoc

thanx for both ov ur advices u av been very helpful,i am goin av a look at 1 frm a salvage yard first so i can see how it is mounted before i touch my own thank you both very much