spongy brakes after master cylinder replacement - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ General Discussion Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 07-26-2012, 05:20 PM   #1
Jeeper
 
flipped73's Avatar
 
Join Date: Aug 2009
Location: Morris,NY(25mi south of Cooperstown)
Posts: 51
Angry spongy brakes after master cylinder replacement

So I loaned to Wrangler to my son-inlaw. It came back with out brakes. Master cylinder was gone. No leaks anywhere so must be master cylinder. Got one bench bled it and installed it. Bled system with a vacuum bleeder. Good brakes till the Jeep is started then they go to the floor.
Bled again with the two person method. Still the same. Today I removed the master cylinder and bled it again . Then bled the system again. Same result.
Any body got any suggestions?
Thanks. Chris

__________________
<<<Thats my first Jeep.
97 Wrangler,01 Grand
flipped73 is offline   Quote Quick Reply
Old 07-26-2012, 06:14 PM   #2
Sponsoring Vendor

WF Supporting Member
 
Black Magic Brakes's Avatar
 
Join Date: May 2011
Posts: 1,819
Quote:
Originally Posted by flipped73 View Post
So I loaned to Wrangler to my son-inlaw. It came back with out brakes. Master cylinder was gone. No leaks anywhere so must be master cylinder. Got one bench bled it and installed it. Bled system with a vacuum bleeder. Good brakes till the Jeep is started then they go to the floor.
Bled again with the two person method. Still the same. Today I removed the master cylinder and bled it again . Then bled the system again. Same result.
Any body got any suggestions?
Thanks. Chris
Did you adjust the booster pushrod before you did the final install?

If the master is the only thing you worked on and it's going to the floor when you start the engine, that means you have air in the system.

When you did the two person bleed, how did you do it and how was the flow out of each corner?

Also, do you have the dash brake light on with the parking brake handle down?

__________________
I am Savvy, I am the brake Wizard.
http://blackmagicbrakes.com
Black Magic Brakes is offline   Quote Quick Reply
Old 07-26-2012, 06:34 PM   #3
Jeeper
 
flipped73's Avatar
 
Join Date: Aug 2009
Location: Morris,NY(25mi south of Cooperstown)
Posts: 51
Quote:
Originally Posted by Black Magic Brakes View Post
Did you adjust the booster pushrod before you did the final install?

If the master is the only thing you worked on and it's going to the floor when you start the engine, that means you have air in the system.

When you did the two person bleed, how did you do it and how was the flow out of each corner?

Also, do you have the dash brake light on with the parking brake handle down?
When we bled it was pump 3 times and hold on the third. We did this till there was no air and the fluid ran clean. Fluid was dark before so figured it was time to flush it out. Did not adjust the booster rod.
Any help is appreciated!!!
__________________
<<<Thats my first Jeep.
97 Wrangler,01 Grand
flipped73 is offline   Quote Quick Reply
Old 07-26-2012, 07:57 PM   #4
Jeeper
 
Join Date: Oct 2008
Location: Jacksonville,Florida
Posts: 457
Either there is still air in the System or you have a defective Master Cylinder,I assume you inspected the brakes on all 4 wheels and the rear brakes are not way out of adjustment,Try Gravity bleeding (Remove M-Cyl Lid open R.R. Bleeder let it drip till clear fluid then close & repeat for L.R-R.F-L.F) Keep fluid topped off while bleeding.
gmiller0737 is offline   Quote Quick Reply
Old 07-26-2012, 08:51 PM   #5
Jeeper
 
freeskier's Avatar
 
Join Date: Mar 2011
Location: Longmont, CO
Posts: 2,464
I donn't know about you but my jeep won't really gravity bleed. Open the bleeder and a few drops come out, that's it. I use Blaine's method for bleeding. Open bleeder, have helper push and hold pedal to floor, close bleeder, helper releases pedal. Repeat until no bubbles. Never had an issue using that method.
freeskier is offline   Quote Quick Reply
Old 07-26-2012, 09:35 PM   #6
Sponsoring Vendor

WF Supporting Member
 
Black Magic Brakes's Avatar
 
Join Date: May 2011
Posts: 1,819
Quote:
Originally Posted by flipped73 View Post
When we bled it was pump 3 times and hold on the third. We did this till there was no air and the fluid ran clean. Fluid was dark before so figured it was time to flush it out. Did not adjust the booster rod.
Any help is appreciated!!!
If you didn't adjust the booster rod, it may be pushing in slightly on the master and not uncovering the ports to the reservoir fully. If the booster drops even a tiny bit in that case, it will block the ports, fluid in the lines will heat up and apply the brakes for you. Typically that ruins pads, rotors, and front calipers because you won't pull over in time.

Don't use that method to bleed brakes. That's very old school and all it does with modern masters is entrain tiny bubbles of air in the fluid which later coalesce into bigger ones.

The best method is described above. You also did not answer my question as to how much flow you were getting? The pedal needs to be pushed to the floor with enthusiasm. It should take a fair bit of effort to keep the fluid line on the bleed screw when the fluid is flowing through it.

What brand master did you buy? If it's A-1 Cardone, you have a high risk of having a bad master out of the box. Find a different brand if that is the case. Centric makes a good one as do Raybestos, Bendix, and Wagner.
__________________
I am Savvy, I am the brake Wizard.
http://blackmagicbrakes.com
Black Magic Brakes is offline   Quote Quick Reply
Old 07-26-2012, 09:38 PM   #7
Jeeper
 
Geoscene's Avatar
 
Join Date: Jul 2012
Location: Moonshine Hill, Texas
Posts: 297
Images: 4
Guess you have checked the lines for leaks?
__________________
My Flickr photostream:
http://www.flickr.com/photos/19387539@N00/
Geoscene is offline   Quote Quick Reply
Old 08-02-2012, 07:02 PM   #8
Jeeper
 
flipped73's Avatar
 
Join Date: Aug 2009
Location: Morris,NY(25mi south of Cooperstown)
Posts: 51
Turns out when I replaced the master cylinder the frozen adjusters in the rear brakes fell out. Thanks for the help guys!

__________________
<<<Thats my first Jeep.
97 Wrangler,01 Grand
flipped73 is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



logo carid shop wrangler parts carid fender flares custom wheels store avs deflectors at carid
» Rates
Get low rates on auto insurance in Canada!

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 09:45 PM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC