Hard Brake Pedal, 97 Chevy Blazer

Old 08-14-06, 08:09 PM
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Hard Brake Pedal, 97 Chevy Blazer

Hi, when I press on my brake pedal, I hear a hissing noise, like air escaping, then the pedal is really hard to press. If I keep pressing for a few seconds, it goes down a little and the car stops. But something is not right. I have not seemed to lose any fluid. Does anyone have an idea? I was thinking either a brake power booster, or a vacuum leak. Any thoughs? Does anyone know how to check the vacuum pressure? Thanks
Old 08-14-06, 08:36 PM
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Sounds like a vacuum booster for the brakes. Get a second person to stand on the brake pedal while you track down the hiss you hear. Something - hose / diaphragm is sucking air rather than pulling a vacuum. Your ears should lead you to the source of the problem.
Old 08-15-06, 06:56 AM
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with the engine not running, pump the brake perdal several times and then hold moderate pressure on it. while maintaining pressure on the pedal start the engine, the pedal should sink under your foot. if it doesn't, the booster is bad

with the engine running, you can pull the hose from the booster under the hood and the engine will change as well as hearing a massive sucking sound. don't do it for long, you'll turn on the MIL (malfunction indicator lamp) or you could install a vacuum guage before starting (about 18 inches of mercury is normal for most engines at idle). my guess is that you don't need to do that because you can hear the leak inside when you depress the pedal which is a classic symptom of a leaking booster diaphragm. get ready to purchase one...

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