# Help with brake pedal - sounds like a tire losing air??



## gli_16v (Aug 27, 2001)

My wife's car... weird, car in park, you can hear a hissing noise very light coming from behind the brake pedal/brake booster area inside the car. Press on the brake pedal, does not matter moving or stopped, and the noise gets way louder, sounds like a tire losing air just behind the brake pedal.
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she has a 99 Toyota Solara...standard abs brakes, no traction control Just a regular MC and a booster behind it. No brake fade/loss of power, hard brakes, nothing, all is fine but for this loud hissing noise which gets really loud when you press the pedal in, even while parked. 
Heard something about lubricating the booster push rod, but I can't get the boot of the rod.















Any thoughts on what the prob could be? hope we don't have to shell out some green for a new booster.


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## Philbert411 (Mar 31, 2003)

*Re: Help with brake pedal - sounds like a tire losing air?? (gli_16v)*

from searching, it sounds like your booster is loosing vacuum


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## Banditt007 (Oct 23, 2002)

*Re: Help with brake pedal - sounds like a tire losing air?? (gli_16v)*

could be as simple as the boosters check valve in the vacuum line, as well as the hose that connects from the intake manifold to the booster. could also be the gasket on the back of the master cylinder that butts up against the brake booster. Not saying it cannot happen, but i very very seldom hear of an actual booster leaking. also a common place for a leak is at the connection of the vacuum line to the brake booster.
try this.
start the car and let it run for about 10 seconds or so. then shut it off. dont touch the brake pedal at any time after you shut it off. wait like 20 minutes. press the brake. if the brake feels very firm and high, you are loosing vacuum, if the brake pedal feels normal for one push of the pedal, chances are you arent loosing vacuum, or you arent loosing much of it.
also to narrow it down would be to disconnect the vacuum line on the brake booster and plug it. then start the car for 10 seconds or so and shut it off. if you still hear this hissing noise, it has nothing to do with the brake booster itself or the seal against the master cylinder. it still can be the vacuum line/valve though.


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