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Old 08-11-2008, 02:21 PM   #1
Dreamof69
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Hissing Coming From Brake Pedal

Does anyone know why? Has it always done this and I am just now noticing? It's really annoying and kinda worrying me like there is something wrong.....
Anyone know what it is?
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Old 08-11-2008, 02:48 PM   #2
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Sounds like your brake booster is about to take a crap on you. Is is getting any harder to push the brake pedal?
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Old 08-11-2008, 02:53 PM   #3
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Quote:
Originally Posted by Panther0876 View Post
Is is getting any harder to push the brake pedal?
Ehh, not that I can tell... when I was driving it a couple days ago it felt like the pedal got stiffer but it went away and now it almost seems like it travels more... but I think it may be a little exaggerated because of the sounds...
...Incidentally, I am right on the other side of the county from you
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Old 08-11-2008, 03:07 PM   #4
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Oh wow look at that! Hows the weather over the grade today?
Mine started making a noise and then from time to time the brakes would feel funny. then it went all together. A quick test would be to remove the vacuum line on the brake booster, plug it with something, then start the car and see if you still have your hissing noise. If it is gone, your booster is on its way out.
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Old 08-11-2008, 03:20 PM   #5
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The weather's pretty good... probably not as good as by the coast, though, so I'm going to give that try a little later tonight and report back on my findings, Thanks!
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Old 08-11-2008, 03:30 PM   #6
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There is a vacuum line attached to a switch on my brake pedal that kicks the cruise control off when the brakes are applied. If your car has the same setup take a look at that vacuum line it could be the source of your hissssssss.
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Old 08-11-2008, 03:38 PM   #7
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There is a vacuum line attached to a switch on my brake pedal that kicks the cruise control off when the brakes are applied. If your car has the same setup take a look at that vacuum line it could be the source of your hissssssss.
I got all down in there and looked but couldn't find anything attached... I'm looking through my FSM right now, though, and I will look to see if I see anything
Thanks!
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Old 08-11-2008, 04:36 PM   #8
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brake booster is going out, i just went through the same thing a few weeks ago. only hisses when the car is running in any gear. and it only has to be pushed enough for the brake lights to come on, not even enoug to slow te car down.

the booster is easy enough to replace. 13mm is all you'll need to do it. take te two bolts off the master cylinder holding it to the booster then remove the knee panel under the driver side of the dash and get a 13mm socket on an elbow with a long extension to get the 2 bolts holding the booster to the firewall. unhook the booster linkage from the pedal by pulling out the cotter pin and then slide the arm off the "bolt" and then it'll slide out, you SHOULD have enough room to get the booster out without disconnecting the master cylinder. which if you can do it that way you wont have to rebleed the brakes unless something it wrong with the master. send me a PM if you have any questions
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Old 08-11-2008, 07:06 PM   #9
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Gotta' agree with the booster fail.

Get your noggin' down near the pedal, and press it with your hand (motor on) - you'll hear the air gettin' by. Motor might start lopin' too - it amounts to a vacuum leak while the pedal is pressed.

There's a bladder/diaphragm in the BB body that has probably ruptured. It was a task swap in a BB in my old '87.
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Old 08-12-2008, 09:21 PM   #10
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If the booster is about to die, is it safe to drive the car?? It feels like the pedal is getting a little softer.
I think this all started when I hit the brakes going ~90.. it felt like it was doing something weird... I don't know if that has anything to do with it.....
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Old 08-12-2008, 09:46 PM   #11
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Quote:
Originally Posted by Dreamof69 View Post
If the booster is about to die, is it safe to drive the car?? It feels like the pedal is getting a little softer.
I think this all started when I hit the brakes going ~90.. it felt like it was doing something weird... I don't know if that has anything to do with it.....
90?

You might have boiled the fluid, and ruptured a line somewhere. That would make for a softer pedal.

BUT, the hissing, if due to a failing BB diaphragm, would make for a HARDER pedal, I'm pretty sure.

Check for Bfluid leaks at the corners.

Did you get your ear near pedal for a listen?
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Old 08-12-2008, 09:50 PM   #12
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Quote:
Originally Posted by Dreamof69 View Post
If the booster is about to die, is it safe to drive the car?? It feels like the pedal is getting a little softer.
I think this all started when I hit the brakes going ~90.. it felt like it was doing something weird... I don't know if that has anything to do with it.....
if the booster totally failed, from my understanding, it would be the equivalent of having manual brakes. wouldn't be unsafe as it would stop, but it would be hard to get te car to stop so in a way very unsafe, if you're not use to manual brakes. just shell out the $120 for a new one and change it yourself. it's easy to do
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Old 08-12-2008, 09:58 PM   #13
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Quote:
Originally Posted by Blade_1 View Post
90?


Check for Bfluid leaks at the corners.

Did you get your ear near pedal for a listen?
I'll definitely check for that.. it's got me a little worried now.. I got down in there and listened and it's definitely hissing down there... like there is a bag of air under the pedal...

I don't mind driving with manual brakes... my abs didn't work for the first year and a half I had the car

I'll get on it but things happen pretty slow around here

Thanks for all the help, everyone!
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Old 08-12-2008, 10:12 PM   #14
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Quote:
Originally Posted by Dreamof69 View Post
I'll definitely check for that.. it's got me a little worried now.. I got down in there and listened and it's definitely hissing down there... like there is a bag of air under the pedal...

I don't mind driving with manual brakes... my abs didn't work for the first year and a half I had the car

I'll get on it but things happen pretty slow around here

Thanks for all the help, everyone!
c373 is correct on booster failure = MANUAL brakes (HARD pedal).

Soft pedal like you say is bothersome. If the fluid boiled, it might NOT be ruptured line, but just air in the lines. LOOK FOR LEAKS, and check the e-break till you know for sure.
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Old 08-12-2008, 10:16 PM   #15
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Quote:
Originally Posted by Blade_1 View Post
and check the e-break till you know for sure.

Funny thing...... I don't have an e-brake
I'm checking for leaks now, though
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