# flapping noise under brake pedal?



## duchykem (Mar 25, 2005)

I have a 2005 Pontiac GTO with around 64000 miles. about a month or so ago it started making a sound I could hear coming from the floor under the brake pedal. It always happens after i start the car and drive it about half a block. (I called it a farting like sound, the technician said sounded like a whoopie cushion sound)..I can start it and let it run forever and it won't do it until i actually Drive it for that same distance and happens every time. A few times had my foot on the brake/or braking at the point it made the noise and i felt a bad vibration under the brake pedal. I took it to the Pontiac shop and they thought ABS, checked it and wasn't so they replaced my brake pads. Still wasn't it and still makes noise. They then decided it was the heat sensors on the cat conv said they fixed it but it still makes the noise. They were to the point they said they would have to research it online but internet was down and would call me back. That was nearly 2 weeks ago and still haven't heard back, my guess is they have no idea what it is. It really bothers me, that car is my baby and if it is something that is going to get worse or cause more problems i need to get it fixed. Any ideas? thank you


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## 68Resto-mod (Nov 10, 2009)

duchykem
I might be way off here but it could be a broken diaphragm or a seal in the break booster assembly. I recall having driven cars with similar brake booster issues and they sure can make some weird noises as the manifold vacuum escapes past the brokeen seal or torn diaphragm.


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## Rukee (Feb 8, 2007)

68Resto-mod said:


> duchykem
> I might be way off here but it could be a broken diaphragm or a seal in the break booster assembly. I recall having driven cars with similar brake booster issues and they sure can make some weird noises as the manifold vacuum escapes past the brokeen seal or torn diaphragm.


A good way to test that would be to pull and plug the vacuum hose going to the booster. Braking effort will be increased, but if it is the booster causing the noise, it shouldn't make the same noise with the vacuum hose removed.


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## Poncho Dan (Jun 30, 2009)

Definitely in the booster. Considering what you said about the repair shop, I wouldn't go back there...


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