Hissing noise when I hit the brakes

I have a 92 Grand AM SE with a Quad 4 engine. Whenever I press hard on the brakes, I heard a hissing noise. It sounds like the sound that you hear when you switch the vent switch from off to vent.

Does anyone have any idea what this hissing noise could be?

[danny]

you should check the power booster behind the master cylinder

[carsandcycles]

Like "danny" said, you have a leaking diaphragm in the power brake booster. It involves disconnecting the master cylinder, disconnecting the brake pedal from under the dashboard that's connectd to the booster, disconnecting the booster from the firewall and replacing the booster. (I don't believe you can repair the booster; you got to get a new one.)

Thanks -- that has been driving me nuts.

How much do you think it would cost to get done? Also, is there a danger of my brakes going out?

[danny]

don't know about the cost, but you should get it replaced as soon as possible. the brakes won't go out but the pedal can get extremely hard to push maybe causing an accident.

So far, it's not doing it all of the time, and when it does do it, it only does it when I hit the brakes hard. Since I am aware of the problem, I will be extra careful with braking distance.

For anyone else who may have the same problem with this in the future, it costs about $300.00 to fix.


Thanks for the info. this hissing was driving me nuts.