Hi,
I have a problem where there are loud hissing sounds when stepping on the brake pedal - the brakes still work fine..but I noticed that I have to press down much harder and lower in order to clamp down completely on the brake. Most of the searches I've found point the possibility to a bad brake booster or master cylinder, so if anybody can help out that would be awesome.

My car was recently repainted, so my mechanic was suggesting that the brake booster might have been contaminated by the paint and dust, but I wanted to check with you guys before changing out unnecessary parts. Also, the floating rotors on the big brake kit were just changed with the brake lines bled, and the motor was put back in after the repaint..so I don't know what could've happened in between all of this.

 

I'd start by checking the brake pads. If they are low, you could be getting a hissing noise as the metal starts to rub, before the squealing starts. It's easy to check your brake pads, they are cheap to replace, and if they aren't the problem, you lose maybe a half hour tops.

 

One would assume that if your brake booster was bad you would get the hissing sound you describe.....
A 'hiss' describes to me a sound being generated by air. A 'squeal' would be generated by your brake pads/rotors.
(or your woman when you slam it home....)

 

Definitely sounds like a leaking brake booster unit by the description.

Worn brake pads won't cause a significant increase in pedal effort like he's describing.

 

I've got a kind of hissing sound only when I press the accelerator lol 2 engines later and it still makes that sound so I assume its normal.

 

I really appreciate the quick replies guys =) I just recently changed my brake pads along with the new rotors, so that shouldn't be the problem. Sounds to me like I might have a leaking brake booster - is the only way of fixing the booster problem by replacing the unit?

 

Yes.

About $125.

Here is a link to one place.

http://www.autopartswarehouse.com/se...67+11064&Nty=1

 

Also, make sure the check valve is functioning properly. It is a one-way valve that keeps boost from entering yet allow vacuum to be pulled.