Brake Booster Dead?
Thread Starter
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Brake Booster Dead?
Well this was fun. Coming to a stop yesterday all of a sudden NO POWER BRAKES! Ahhhh 2-feet slam quick! :lol:
So I started paying attention to it. If I drove a little ways I had power brakes. If i immediatley tried to use them again, no power brakes. Hmm, neato! So then... I remembered something else. Every time I hit the brakes I had this electrical "white noise" which I thought was coming from the speaker in the door. I thought maybe a line was crossed up with the brake light circuit and speaker circuit and it didn't really matter to me. Then it hit me "Idiot, thats vaccum you're hearing!!"
SO..... anyone else had this vacuum leak only when on the brakes before? I guess I have to replace the booster as the vaccum line itself to the plenum seems fine. That is unless some of you know of a seal in that area where the brakes connect that can just be replaced.
Thanks. :)
So I started paying attention to it. If I drove a little ways I had power brakes. If i immediatley tried to use them again, no power brakes. Hmm, neato! So then... I remembered something else. Every time I hit the brakes I had this electrical "white noise" which I thought was coming from the speaker in the door. I thought maybe a line was crossed up with the brake light circuit and speaker circuit and it didn't really matter to me. Then it hit me "Idiot, thats vaccum you're hearing!!"
SO..... anyone else had this vacuum leak only when on the brakes before? I guess I have to replace the booster as the vaccum line itself to the plenum seems fine. That is unless some of you know of a seal in that area where the brakes connect that can just be replaced.
Thanks. :)
Thread Starter
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: Brake Booster Dead? (scorp508)
http://www.alldatadiy.com
Hard Pedal
Power brakes that have a hard pedal are usually suffering from a milder form of the same ills that cause complete power unit failure. Collapsed or leaking vacuum lines or insufficient manifold vacuum, as well as punctured diaphragms or bellows and leaky piston seals, all lead to weak power unit operation. A steady hiss when the brake is held down means a vacuum leak that will cause poor power unit operation.
Hard Pedal
Power brakes that have a hard pedal are usually suffering from a milder form of the same ills that cause complete power unit failure. Collapsed or leaking vacuum lines or insufficient manifold vacuum, as well as punctured diaphragms or bellows and leaky piston seals, all lead to weak power unit operation. A steady hiss when the brake is held down means a vacuum leak that will cause poor power unit operation.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Brake Booster Dead? (scorp508)
There seems to have been a rash of booster failures over the past few months; mine included. I went out one morning and had a hard pedal and it turned out to be a cracked booster.
From my experience and from the posts of others, the failures seem to be caused by header heat. Mine had a crack over 6" long on the side closest to the headers.
One of the mags ran an article and showed a photo of an 88 (I believe) that had a fabricated heat shield on the booster. It was installed on the side closest to the header. I did the same with my new booster.
Only after I installed the new one (which is plastic too) did I learn that there is a metal booster available for only a few dollars more.
Jake
[Modified by JAKE, 2:40 PM 5/14/2004]
From my experience and from the posts of others, the failures seem to be caused by header heat. Mine had a crack over 6" long on the side closest to the headers.
One of the mags ran an article and showed a photo of an 88 (I believe) that had a fabricated heat shield on the booster. It was installed on the side closest to the header. I did the same with my new booster.
Only after I installed the new one (which is plastic too) did I learn that there is a metal booster available for only a few dollars more.
Jake
[Modified by JAKE, 2:40 PM 5/14/2004]
Le Mans Master
Joined: May 2003
Posts: 5,362
Likes: 3
From: Delray Beach FL
Re: Brake Booster Dead? (JAKE)
Scorp,
Before you buy a booster, replace the check valve. Sometimes, these will get plugged up or just fail, causing the same feeling as the brake booster. It is under $20 for the part and takes minutes to install. You just pull the check valve out of the booster and pull off the vacuum line, reinstall new one. If your brakes are still very hard, then replace the booster. Good luck. :smash:
Before you buy a booster, replace the check valve. Sometimes, these will get plugged up or just fail, causing the same feeling as the brake booster. It is under $20 for the part and takes minutes to install. You just pull the check valve out of the booster and pull off the vacuum line, reinstall new one. If your brakes are still very hard, then replace the booster. Good luck. :smash:
Drifting
Joined: Mar 2004
Posts: 1,522
Likes: 0
Re: Brake Booster Dead? (scorp508)
I have that hiss when I hold the brake down, and my brake pedal is pretty hard, I haven't had the car very long, but I would like to fix it. Is there any specific place I should check for a vacuum leak? (I have a 96 LT4). Thanks!
Le Mans Master
Joined: May 2003
Posts: 5,362
Likes: 3
From: Delray Beach FL
Re: Brake Booster Dead? (Cold_B)
Check your brake booster check valve and the hose running to it for cracks. I'd replace the check valve as it is a cheap part, just to be on the safe side. If it still gives the hiss, then your booster may be on its way out.
Instructor
Joined: Apr 2004
Posts: 240
Likes: 0
From: St. Louis MO
Re: Brake Booster Dead? (Whitvette)
This is common on these vettes for some reason. I just replaced mine last year.
Don't bother replacing the check valve, because the new booster will come with it. If you are getting a distinct hissing from underneath the floor by the pedal, I would be certain it is the booster. Mine got hard like yours did, and then would be ok when I drove for a bit, I guess long enough before enough vacuum leaked out.
I guess if you really think it's the check valve you could change that, but then you'll just have an extra one when you buy the booster.
Just my 2c.
Don't bother replacing the check valve, because the new booster will come with it. If you are getting a distinct hissing from underneath the floor by the pedal, I would be certain it is the booster. Mine got hard like yours did, and then would be ok when I drove for a bit, I guess long enough before enough vacuum leaked out.
I guess if you really think it's the check valve you could change that, but then you'll just have an extra one when you buy the booster.
Just my 2c.
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Thread Starter
Team Owner
Joined: Mar 2000
Posts: 83,383
Likes: 87
From: Boston, MA
Re: Brake Booster Dead? (88vettelover)
Don't bother replacing the check valve, because the new booster will come with it. If you are getting a distinct hissing from underneath the floor by the pedal, I would be certain it is the booster.
Instructor
Joined: Apr 2004
Posts: 240
Likes: 0
From: St. Louis MO
Re: Brake Booster Dead? (scorp508)
Scorp, I think I got my brake booster for pretty cheap. It was plastic, but I may be able to get a good deal on it for ya.
I'll find out sometime tomorrow and get back with ya. :D
I'll find out sometime tomorrow and get back with ya. :D
Burning Brakes
Joined: Jan 2001
Posts: 1,169
Likes: 0
From: Manhattan
Re: Brake Booster Dead? (scorp508)
Scorp, mines been broken for a few months now. I checked the chain parts stores, autozone or advance, had two different ones for a 1990. One was twice the shipping weight of the other, they were both around $100. I'm assuming the heavy one is the metal one. Personally, i'll take the lighter one, even if i have to replace it every few years.
