1990 Chevy 1/2 ton Master Cylinder Bubbling - Off-Road Forums & Discussion Groups
GM Standard IFS Trucks & SUV's All discussion of full sized IFS Trucks, SUV's to include Suburban

LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 10-08-2011, 06:17 PM Thread Starter
Join Date: Sep 1999
Location: Mid Michignan
Posts: 322
Thanks: 0
Thanked 0 Times in 0 Posts
Angry 1990 Chevy 1/2 ton Master Cylinder Bubbling

While trying to diagnose my brake light coming on I noticed something I haven't noticed before. The truck is a 4x4 with RWABS. When I first apply the brakes I may get a warning light on the dash and the pedal feels a little low, pressing on it again turns off the light and the pedal seems more firm. Had my wife press the pedal while I was under the hood looking for clue. I noticed the reservoir for the front brakes (the rear most reservoir) would bubble like air was entering from the bottom or that fluid was being forced back into the master cylinder. I also noticed that the front of the power booster was moving outward a bit. It did not matter if the engine was running or not. I also now a steady brake failure light and can not pull any brake error codes.
Any ideas of that might be wrong or how to fix it?
wsmm is offline  
Sponsored Links
post #2 of (permalink) Old 12-24-2011, 06:28 PM
texas sub's Avatar
Join Date: Jan 2009
Location: Texas or suburbia hell havnt figuered which
Posts: 141
Thanks: 0
Thanked 2 Times in 2 Posts
if youre getting bubles that means that there is an air leak some where and the boster should not move at all. the bolts holding it probably came loose or broke. sorry to hear that its a pain getting to the top ones

Idiot proof is a lie considering that all of the idiots have tried it.
texas sub is offline  
post #3 of (permalink) Old 01-11-2012, 02:18 AM
Join Date: Jun 2011
Location: texas, usa
Posts: 21
Thanks: 0
Thanked 1 Time in 1 Post
currently suffering the same problem and i dunno what to do. i also think that this problem is not a do it yourself thing so this week i will be just looking for an independent mechanic that could fix my ride. it will be more advisable to bring it to your dealer because they know best but that is only my last option. please update me what did you do to fix it. i really dont have any idea where to start even looking for Chevrolet Parts is tough.

Last edited by ronierogers; 01-14-2012 at 11:58 PM.
ronierogers is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


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
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may not post new threads
You may not 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 On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome