Corvette Forum : DigitalCorvettes.com Corvette Forums banner

Hissing Coming From Brake Pedal

9K views 17 replies 7 participants last post by  Dreamof69 
#1 ·
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?
 
#3 ·
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 :thumbsup:
 
#4 ·
Oh wow look at that! Hows the weather over the grade today? :cheers:
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.
 
#6 ·
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.:thumbsup:
 
#8 ·
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
 
#9 ·
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.
 
#10 ·
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.....
 
#11 ·
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?
 
#13 ·
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:laughing:

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

Thanks for all the help, everyone!
 
#16 ·
My friend has an 89 and he has changed his booster 3 times... it just started hissing again the other day.... :bang
 
#17 ·
You'll do know that if the master cylinder leaks brake fluid past the plunger in to the brake booster the brake fluid will eat the boosters diaphragm, causing the pedal to get softer and make a hissing noise.

And 90 is not going to boil the brake fluid, unless you are using water in your brake system.
I had to hit my brakes at 140 ( I had just seen the nose of a cop car sticking out from the bushes) and had to hit them, but I did not have any problems out of mine after that.

I seriously doubt Chevy would design a car that will run 150, but you can't use the brakes over 90!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top