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Old 05-23-2013, 05:19 PM   #1
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02 TJ Losing Brake Pressure When Applied Continuously

I did a search here first, but nothing came up.

Driving today, stopped at a red light. Noticed it started to creep forward. Had to keep applying more pressure to stay stopped. When I started driving again, brakes were fine. I got to work and checked the fluid, full. I didn't see any leaks underneath. Driving home, same thing at every prolonged stop. Master cylinder? Easy self fix? Bench bleed hard or easy? Never done before, but don't have the $ to pay a garage. Thoughts and suggestions?

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Old 05-23-2013, 05:24 PM   #2
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might be your brake booster? not sure though it seems odd that it just occurs after prolonged period of braking, how old are your brake pads, shoes, rotors and drums... ?

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Old 05-23-2013, 05:33 PM   #3
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I have no clue. I've had it about a year, sp older than that.
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Old 05-23-2013, 05:35 PM   #4
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My jeep idle bumps up after a while sitting at a light, so if I don't have enough pressure it will try to push forward.
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Old 05-23-2013, 05:45 PM   #5
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It's definitely not that. After a minute, the pedal is about on the floor.
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Old 05-23-2013, 06:02 PM   #6
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Quote:
Originally Posted by Amocat00 View Post
I did a search here first, but nothing came up.

Driving today, stopped at a red light. Noticed it started to creep forward. Had to keep applying more pressure to stay stopped. When I started driving again, brakes were fine. I got to work and checked the fluid, full. I didn't see any leaks underneath. Driving home, same thing at every prolonged stop. Master cylinder? Easy self fix? Bench bleed hard or easy? Never done before, but don't have the $ to pay a garage. Thoughts and suggestions?
You may have a leak somewhere in one of your drum brakes. I have the same problem, took me forever to find the leak because it was dripping down the tire, making it hard to see. That's on my list of things to fix... quickly.
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Old 05-23-2013, 06:15 PM   #7
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Inspect your brakes from end to end if you find no leaks and are not loosing brake bluid your Brake Master Cylinder is "Bypassing" or leaking internaly which will cause the pedal to drop as you hold pressure on the brake.
There's really no easy way to test the master cylinder however sometimes when you remove it you'll find fluid between it and the booster.
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Old 05-23-2013, 06:19 PM   #8
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I'll check for leaks again. But, the brake fluid reservoir is right at the full mark and I've never added anything to it.
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Old 05-23-2013, 06:23 PM   #9
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It's most likely a bypassing Master Cylinder then.
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Old 05-23-2013, 08:13 PM   #10
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It's most likely a bypassing Master Cylinder then.
I guess that's where I'll start. Thanks for the help.
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Old 05-23-2013, 09:18 PM   #11
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if your not loosing fluid from a broken line or leaking caliper / wheel cylinder then the most likely cause is your master cylinder is letting fluid bypass it. As you try to hold on the brakes, the pressure forces the fluid back into the master cylinder acting as if you are taking your foot off the brake when your really not. Get this replaced soon or else there will come a time when you step on them and they will not do anything...
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Old 05-24-2013, 01:37 AM   #12
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you need a new master cylinder... it has an internal leak.... replace as soon as possible...
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Old 05-24-2013, 08:49 AM   #13
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Just reserved a Fenco master cylinder at Auto Zone. $63.00 and includes a brake bleeder kit. So, I should be good to go. Thanks all, for your help.
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Old 05-25-2013, 09:07 PM   #14
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Fixed!!! Thanks to a couple local, nice, knowledgeable Jeepers. Thank you!

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