Brakes boging down idle??? - JeepForum.com
 
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post #1 of 5 Old 12-30-2012, 09:06 AM Thread Starter
scottcj71979
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1979 CJ7 
 
Join Date: Nov 2012
Location: jacksonville
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Brakes boging down idle???

When I press the brakes and apply pressure it bigs down idle and when it's cold can kill the engine. The pressure I have to use to get it to stop seems much stronger lately as well.

Is it something to do with my brake booster? Can this be adjusted in anyway? Anything to look for?

Thanks for the help!

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post #2 of 5 Old 12-30-2012, 10:05 AM
turbolx
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Sounds like you have a leak in the booster diaphragm. It runs off of vacuum from the engine and if there is a leak in the diaphragm, it will cause a vacuum leak in the engine and affect the idle speed.
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post #3 of 5 Old 12-30-2012, 10:12 AM
90DesertTanYJ
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1990 YJ Wrangler 
 
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Quote:
Originally Posted by turbolx View Post
Sounds like you have a leak in the booster diaphragm. It runs off of vacuum from the engine and if there is a leak in the diaphragm, it will cause a vacuum leak in the engine and affect the idle speed.
I agree. The added effort on the brake pedal is your next clue. Just like pushing the pedal after the Jeep is turned off. Eventually you have to stand on them for them to work.
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post #4 of 5 Old 12-30-2012, 06:09 PM Thread Starter
scottcj71979
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1979 CJ7 
 
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Yep did some trouble shooting and it's Definatly the brake booster. Guess it has a leak internally so I'm going to replace the whole unit and master cylinder from a 1979 wagoneer. For some reason at the parts store they didn't have one under any cj models but did for the wagoneer. It looked the same as the one I have on there. Hopefully it works.?

I was 4x4 in low all night long then it started to leak. 35" tires plus upgraded axels doesn't help I'm sure, but it looks original so maybe it was just its time to retire?
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post #5 of 5 Old 01-01-2013, 07:35 AM Thread Starter
scottcj71979
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Location: jacksonville
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