97 brake pedal makes shhhh sound like air leaking

[comet240]

my moms car 1997 cavalier.. it doesn't always happen but when it does she has no brakes. and when you press to the floor the brake pedal when pressed to the floor sounds like air leaking from when you have an air hose hooked up to your compressor and it makes the shhhhhhhh sound... the brake pedal does that but only when fully pressed... but then after several pumps brakes work again and that shhhhh is gone... what does that mean

doesn't always happen

random times

[gmtech1]

Sounds like you have a vacuum leak at the brake booster. It would need to be replaced, don't think they make service kits for those anymore.

[comet240]

ah ok car not here is it just a rubber hose to replace then? and is that why she lost brakes then or I never drove it so I guessing youd have to press harder then

[gmtech1]

Not just a hose, the entire booster will need to be replaced.

[comet240]

oh its big round thing then not just a hose then
so whats broken is inside it then?

[gmtech1]

There are rubber seals and diaphrams that tear and leak vacuum. At one time a person could buy rebuild kits for the booster, but I don't think they are available anymore. Cheaper and safer to buy a replacement booster.

[Tech II]

Also check that rubber hose AND and the check valve, where it enters the booster......with engine off, grab the hose and move it around slightly......if you hear vac escape, could be the check valve/seal at the booster...otherwise, you are looking at a booster, as GMTech1 says......not an easy job for a DIY'er....