brake pedal going to the floor!! - JeepForum.com

 
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post #1 of 8 Old 12-19-2011, 05:23 PM Thread Starter
Dustem
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1994 XJ Cherokee 
 
Join Date: Dec 2011
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brake pedal going to the floor!!

Hello, I need help on my 1994 grand cherokee. Back brake shoes have 2000 miles on them. Front pads about 1000 miles since replaced. New wheel cylinders and drums on the back and rotors on the front. I have inspected all brake lines and hoses for leaks. Brake fluid level is fine. Three out of five times the pedal will go to the floor real slow when stopping. Brake light comes on and it will start rolling! You can let off the brake and sometimes it will hold, sometimes it wont. Does the same thing in neutral. Vaccum is good to the booster. Dont know what the small round cylinder is that the brake lines go to out of the master cylinder. It also has two rubber lines. Thanks GB

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post #2 of 8 Old 12-19-2011, 07:43 PM
RTYauch301
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sounds a bit like the master cylinder is gone but you said it has new wheel cylinders... did you bleed them properly may just have air in the lines
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post #3 of 8 Old 12-19-2011, 08:04 PM
edpmedic
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Did you loose all the fluid when you changed the cylinders. If you lost the fluid in the master it needs to be bled. I would then go to the right rear and stick a tube on the blender screw. Stick the other end into a clear jar with brake fluid. Then pump the pedal and look for air bubbles. Repeat on left rear. Then right front then left front.

I use a mighty vacuum with the bleeder system they sell them at autozone or pepboys worth every penny. If no air and abs light is not on and if it goes to floor. Then you pump it up and had your foot on it and slowly goes down I would then say it is the master.

I am sure the emergency brake and the shoes are adjusted properly.

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post #4 of 8 Old 12-19-2011, 08:59 PM Thread Starter
Dustem
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I have recently moved and could not find my tool that you pump to pull the air out of the lines. I did push a little fluid out of the front of the master cylinder when doing the front brakes so I added fluid as I bled them. I took my time bleeding both ends by pumping the pedal but maybe I need to use the bleeder to make sure all air is out. When using the vacuum tool I think I am suppose to push and hold the brake pedal in just about 1 to 2 inches? Is that correct? I will give it a try. If it is air I still dont understand why it took this long to be a problem. Your help is greatly appreciated. Thanks, GB
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post #5 of 8 Old 12-20-2011, 08:05 AM
RTYauch301
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Quote:
Originally Posted by Dustem View Post
I have recently moved and could not find my tool that you pump to pull the air out of the lines. I did push a little fluid out of the front of the master cylinder when doing the front brakes so I added fluid as I bled them. I took my time bleeding both ends by pumping the pedal but maybe I need to use the bleeder to make sure all air is out. When using the vacuum tool I think I am suppose to push and hold the brake pedal in just about 1 to 2 inches? Is that correct? I will give it a try. If it is air I still dont understand why it took this long to be a problem. Your help is greatly appreciated. Thanks, GB
if it didnt do it right away then im 98% sure your master cylinder has failed
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post #6 of 8 Old 12-20-2011, 10:37 AM Thread Starter
Dustem
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Thanks for all the help!
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post #7 of 8 Old 12-21-2011, 06:53 AM
edpmedic
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Quote:
Originally Posted by RTYauch301 View Post
if it didnt do it right away then im 98% sure your master cylinder has failed
I agree with that. I would look for signs of the power
booster being wet or move the mat under the dash and look for signs of floor being wet. That's if it is leaking out. If you said your not losing fluid its internal. Like I said if you sit there and have a good pedal. Then it bleeds down most likely the master. If the pedal is spongy and it pumps up and gets hard usually then its air.

Sorry for spelling and grammar I'm doing this on my phone and I it doesn't word wrap. Its like one continuous line...got to figure why it does that.

Never4get those who gave their lives on 09-11-01 WTC and Pentagon. FDNY-EMS-NYPD-PAPD. Also those who are still dying.
_______________________________________________
"Freedom is never voluntarily given by the oppressor; it must be demanded by the oppressed."
Martin Luther King, Jr.
_______________________________________________
"Always aim at complete harmony of thought and word and deed. Always aim at purifying your thoughts and everything will be well."
Mahatma Gandhi
_______________________________________________
Feel the Sunshine on your face
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post #8 of 8 Old 01-10-2012, 01:27 PM Thread Starter
Dustem
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1994 XJ Cherokee 
 
Join Date: Dec 2011
Location: Bristol
Posts: 4
Brake trouble

Bled the brakes with 'tool' and nothing changed. Took all three plugs (electrical)loose from brass fitting that brake lines go to and ABS motor. Drove Jeep and problem quit. Then I unplugged the long rectangle plug on a box mounted on the drivers inner fender. It is a brake control box. I guess I reset some kind of problem but it is O.K. for now. I have drove it about 200 miles with no brake issues. Thanks for all the input and help, GB
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