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Brake Booster Diagnostic

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Old 12-22-2014, 06:48 PM
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Default Faulty Brake Booster or...

Hello, I just want to know if my brake booster is quitting on me. The symptoms i got so far is hard braking and the pedal goes all the way down. Checking when arrived to my home and notice a air sound near the pedal and notice a change in the idle. Posting a little vid of what i found so anyone can advised me.Thanks
http://youtu.be/-TPaJaKpa9A?list=UU3Irudj3FeqfFw8BPtB8uvg
Also my jeep is a 95 Cherokee SE 2WD

Last edited by petejeep95; 12-22-2014 at 07:55 PM. Reason: better title
Old 12-23-2014, 05:27 AM
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Narrow down air sound . Could be cruise switch at pedal defective if you have cruise of course. If not most likely booster on its way out.
Old 12-23-2014, 06:30 AM
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Thanks freegdr, i don't have cruise so i will change the booster this morning.
Old 12-23-2014, 10:45 AM
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Hard braking and air sound are symptoms of the booster failing, however pedal all the way down does not sound to me right, as a broken booster will not facilitate the pedal going all the way down, as a matter of fact will be a lot harder to push, pedal all the way down to me has to do with the brake master cylinder.

Just double check everything, broken booster will behave equal to when the truck is off (after pushing the pedal a few times and emptying the vacuum accumulated on the vacuum bottle)

Good luck

Last edited by lualchro; 12-23-2014 at 10:48 AM.
Old 12-23-2014, 06:13 PM
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when you unbolt the master cylinder from the booster, check to make sure it is not leaking fluid into the booster........................This would cause the booster to fail, and also possibly cause your pedal going to the floor issue.............


Normally when the booster fails, the pedal gets really hard to push down....




Your video definitely sounds like the booster diaphragm has failed!
Old 12-23-2014, 08:58 PM
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Thanks to everyone really! I just replaced the booster, i couldn't see the master cylinder leaking so after putting it together braking seems to be like before. Also i need to adjust the rear brake shoes that's why i have soft braking but not much. Thanks

Last edited by petejeep95; 12-23-2014 at 09:08 PM.
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