No Brakes
massages
10-04-2004, 07:01 PM
1997 Chevy S-10 drove ok all day. Almost made it home and the brakes quit working. Its hard to press the brake pedal and make it stop. Got to fooling around with it and it makes a hissing sound while you press the brake pedal and when you put it in drive it idles real bad(almpost shuts off. What is wrong?
sector95
10-04-2004, 07:07 PM
1997 Chevy S-10 drove ok all day. Almost made it home and the brakes quit working. Its hard to press the brake pedal and make it stop. Got to fooling around with it and it makes a hissing sound while you press the brake pedal and when you put it in drive it idles real bad(almpost shuts off. What is wrong?
Where does the hissing sound seem to come from? There is a large chamber, a big diaphragm, located on the firewall behind the master cylinder. There is a large vacuum hose running from the diaphragm to the intake manifold.
Where does the hissing sound seem to come from? There is a large chamber, a big diaphragm, located on the firewall behind the master cylinder. There is a large vacuum hose running from the diaphragm to the intake manifold.
massages
10-04-2004, 09:05 PM
sounds like the noise is right under the dash where the brake pedal is
sector95
10-04-2004, 10:11 PM
sounds like the noise is right under the dash where the brake pedal is
Okay... how about when you listen under the hood? Can you hear it there? If so where?
Okay... how about when you listen under the hood? Can you hear it there? If so where?
BlazerLT
10-04-2004, 11:23 PM
Every brake system hisses a bit when you press the gas.
The hard breaking is because the vacuum assist s low from the engine.
Check the large tube going from the master cylinder to the engine for leaks.
Thats the hose for vacuum assist.
BTW, any check engine lights on?
The hard breaking is because the vacuum assist s low from the engine.
Check the large tube going from the master cylinder to the engine for leaks.
Thats the hose for vacuum assist.
BTW, any check engine lights on?
sector95
10-05-2004, 10:15 AM
Every brake system hisses a bit when you press the gas.
The hard breaking is because the vacuum assist s low from the engine.
Check the large tube going from the master cylinder to the engine for leaks.
Thats the hose for vacuum assist.
BTW, any check engine lights on?
Blazers right about *a bit* of hissing when you step on the brakes...but it sounds like yours hiss all the time...not normal... and given your "hard pedal" it appears your loosing boost.
Listen under the hood with the engine running...you may need someone to step on the brakes while you listen. The brake booster is the large round thing the master cylinder it mounted to. Connected to the booster will be a large diameter (approx 1" dia) vacuum hose. It will typically be connected to an elbow fitting on the booster and connect to the intake manifold; this is the source of vacuum to operate the booster.
You might have something as simple as a hose connection that needs to be reseated or a cracked elbow fiitting. Or...a bit more involved (and a bit more expensive) an internal leak in the brake booster itself. Hopefull you'll be able to isolate the problem with a listen.
mike
The hard breaking is because the vacuum assist s low from the engine.
Check the large tube going from the master cylinder to the engine for leaks.
Thats the hose for vacuum assist.
BTW, any check engine lights on?
Blazers right about *a bit* of hissing when you step on the brakes...but it sounds like yours hiss all the time...not normal... and given your "hard pedal" it appears your loosing boost.
Listen under the hood with the engine running...you may need someone to step on the brakes while you listen. The brake booster is the large round thing the master cylinder it mounted to. Connected to the booster will be a large diameter (approx 1" dia) vacuum hose. It will typically be connected to an elbow fitting on the booster and connect to the intake manifold; this is the source of vacuum to operate the booster.
You might have something as simple as a hose connection that needs to be reseated or a cracked elbow fiitting. Or...a bit more involved (and a bit more expensive) an internal leak in the brake booster itself. Hopefull you'll be able to isolate the problem with a listen.
mike
Mikado14
10-05-2004, 10:45 AM
In your original post, you mentioned that the hissing is:
"Got to fooling around with it and it makes a hissing sound while you press the brake pedal and when you put it in drive it idles real bad(almpost shuts off. What is wrong?"
If the hissing is heard when you press the brake pedal, the hose for vacuum is connected and what you are hearing is a ruptured vacuum boost. You need a new booster. This will cause a vacuum loss even when you are not pressing the pedal (pressing the pedal only allows you to hear it in the cab) and thus the crappy running.
To check this, find the large hose going to the "big round black thing" in back of the master cylinder. This hose will be the size of your heater hose. Unplug it from the booster and then plug the end of the hose. Start your truck up and put it in drive. If it idles ok, you found the vacuum leak, it's the booster.
"Got to fooling around with it and it makes a hissing sound while you press the brake pedal and when you put it in drive it idles real bad(almpost shuts off. What is wrong?"
If the hissing is heard when you press the brake pedal, the hose for vacuum is connected and what you are hearing is a ruptured vacuum boost. You need a new booster. This will cause a vacuum loss even when you are not pressing the pedal (pressing the pedal only allows you to hear it in the cab) and thus the crappy running.
To check this, find the large hose going to the "big round black thing" in back of the master cylinder. This hose will be the size of your heater hose. Unplug it from the booster and then plug the end of the hose. Start your truck up and put it in drive. If it idles ok, you found the vacuum leak, it's the booster.
busa_4
10-05-2004, 03:56 PM
if you hear hissing you can gaurantee its the booster. the vacuum diaphram has failed internally. buy a booster. before you turn in the booster for a core, check to see if it is wet with brake fluid. not many boosters fail just from use. they usually fail when the master cylinder fails internally causing brake fluid to leak into the booster. a good sign of this failure is brake fluid leaking on your floor board. this is very common on vehicles that are strored or sitting for a while as the brake fluid becomes a strong acid. make sure you check your master cylinder as you will be doing this again if it is leaking. good luck!
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