# hissing from brake pedal area?



## rextheracer (Jul 3, 2008)

i noticed that whenever im moving at slow speeds, i can hear the brake pedal hissing....when i press it the hissing goes away....

any ideas? the last thing i want is no brakes for some stupid reason.....


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## MJGTOWISH (Jun 15, 2006)

Got a snake in there ? lol


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## rextheracer (Jul 3, 2008)

haha, hopefully thats the case...itd be alot cheaper to get rid of the problem....haha


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## MJGTOWISH (Jun 15, 2006)

There is a slight hiss in all my cars will not hiss just air, but i have to stomp it do do that though....


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## BMR Sales (Feb 12, 2009)

Check for a vacuum leak of some kind. Does the car still run ok?


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## Poncho Dan (Jun 30, 2009)

That is a power booster vacuum leak, and it will only get worse with time as the diaphragm inside tears further. When it goes, it's going to feel like you're stepping on a brick.


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## rextheracer (Jul 3, 2008)

Poncho Dan said:


> That is a power booster vacuum leak, and it will only get worse with time as the diaphragm inside tears further. When it goes, it's going to feel like you're stepping on a brick.


ugh, i feel like your avatar....a big ole money pit. any idea how much thatll cost me?


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## Poncho Dan (Jun 30, 2009)

No idea. I don't have a factory repair manual yet () to know if the booster is a separate, remote unit from the master cylinder, since I remember the master cylinder being on the passenger side. Let me have a look tomorrow when the sun comes out... Are you getting a BRAKE/(!) light on the dash along with this?


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## rextheracer (Jul 3, 2008)

Poncho Dan said:


> No idea. I don't have a factory repair manual yet () to know if the booster is a separate, remote unit from the master cylinder, since I remember the master cylinder being on the passenger side. Let me have a look tomorrow when the sun comes out... Are you getting a BRAKE/(!) light on the dash along with this?


no brake light (yet anyways)....the hissing only occurs when my foot is totally off the pedal, then with any kind of pressure it goes away..


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## Poncho Dan (Jun 30, 2009)

rextheracer said:


> no brake light (yet anyways)....the hissing only occurs when my foot is totally off the pedal, then with any kind of pressure it goes away..


Weird... do you notice it more on deceleration vs cruising?


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## rextheracer (Jul 3, 2008)

Poncho Dan said:


> Weird... do you notice it more on deceleration vs cruising?


it happens when im just sitting as well as decelerating...it might go away under acceleration, but i cant tell cause of the exhaust..


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## BMR Sales (Feb 12, 2009)

Its definitely a vacuum leak. When you accelerate the vacuum is going to change but the leak is still there. Good luck.


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## Poncho Dan (Jun 30, 2009)

Yeah, its the booster (big black circular thing behind the fluid reservoir). That's the only thing over there that needs vacuum.


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## rextheracer (Jul 3, 2008)

so im guessing the leak affects braking performance...so is there a way to fix the leak? or do i need to replace the booster?


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## Poncho Dan (Jun 30, 2009)

You'll need to replace the booster at some point. It won't affect braking performance other than you'll have to push down real hard to get the brakes to work, like doing a Flintstone stop. I'm not sure how it comes apart on the GTO, but in the past, I've had to disconnect the brake lines from the master cylinder, then get down in the footwell under the dash, and unbolt the booster from the inside. The whole thing should pull out together, then you disconnect the master cylinder from the booster.

It took me a while to find the parts Pontiac GTO Brake Booster - Partstrain.com

It doesn't look like Advance Auto Parts or Autozone has them.


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