hissing brakes...

[VSCristian]

I've noticed a problem with my brakes and it's driving me insane:

when I press the brake pedal, there's a hissing sound, and the brakes are very weak, quite similar to placing the tranny in neutral when the car's in motion, switching off the engine, and braking without any power assistance.

when the car is idling and I have my foot on the brakes, there's a hissing sound. What has me baffled is that my pads are good, my fluid is really good too, it's really starting to annoy me. If I fully depress the brake pedal, the car brakes like normal (tho that hissing sound's still there).

any thoughts?

[BENJAMUM]

sounds like your brake booster

[RX25SE]

As above, the booster is stuffed.
When you apply the brakes it creates a vacuum leak which is the hissing sound (most likely from under the dash).
Fix it ASAP as this is quite dangerous.

[VSCristian]

how do I fix it? how much would it cost to fix? will it deteriorate?

[Brett_jjj]

You need to get a new brake booster fitted as its unsafe to drive it like that..Also if the engine can suck air in through a leaking brake booster it wont be running at its best as it the air going into the engine is bypassing the idle air control (IAC) valve,which controls the engine idle speed.It will probably make it idle a bit faster than normal.

[VSCristian]

are they pricey?

[hako]

You can get one from a wrecker for about $100 with the master cylinder attached which is the way I'd do it. Not a big job if you know what you are doing OR do all the necessary research.

[spoiled1]

I just replaced my brake booster on my 97 Vs 6 cylinder, was a relatively easy process, followed the workshop manual. I experienced a hissing sound when applying the brakes, priced a reconditioned booster exchange would have been around $240 got a brand new one for $225 (cost price) retail they are around $334. My suggestion would be to replace it with a new one, but if your strapped for cash you can get one from the wreckers fairly cheap, but no guarantee it's going to last, most of the wrecks have been sitting around for a while, chances are the diaphragm inside the boosters would be pretty worn. No use taking unnecessary chances with your brakes, you want them to work reliably when applied.