Noise when applying brakes then pedal goes to the floor

2003 CHEVROLET TRAILBLAZER
145,000 MILES • 6 CYL • 4WD • AUTOMATIC
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KLUTHIN
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Sometimes when applying my brakes it makes like a ssh. sounds kind of like air in it and brakes go to floor, also have a hard time stopping. It does not do not all the time but more then not. My ABS light is on also as check engine light. is it my master cylinder that needs replaced? Only car I have and I am kind of scared to drive it. Specially going down a hill it does not want to stop when applying the brakes so I just keep pumping them to try to get it to stop.
Apr 7, 2018 at 6:38 PM
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CARADIODOC
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Intermittent loss of pedal does point to a bad master cylinder. If there was an external leak, you would have a low pedal all the time and you would be losing brake fluid. If the fluid level is going down in the reservoir, the best suspect is a leaking rear wheel cylinder. Sometimes they can seal after the brakes are released, and sometimes they can leak, depending on the orientation of the rubber lip seals when they retract.
Apr 7, 2018 at 7:01 PM
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ASEMASTER6371
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Good evening.

The noise you hear is a vacuum leak from the power brake booster. it is leaking vacuum. that could be the cause of the hard stopping. it needs to be confirmed to be sure.

if it is, you will need to replace the booster.

as far as the ABS light, there is a malfunction in the electronic controls. A code is stored in the system. you can have this code read at a parts store for free. once we know the code, it will give us a clue as to the area of failure. in most cases, it is a wheel speed sensor but needs to be confirmed.

Roy
Apr 7, 2018 at 7:13 PM
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