"91 Buick Park Avenue Brake Problem

Reply

  #1  
Old 05-15-05, 02:18 PM
Member
Thread Starter
Join Date: Oct 2003
Posts: 21
"91 Buick Park Avenue Brake Problem

On my 1991 Buick park ave. equipped with ABS the Front passenger caliper and the driver side rear drum brake will not relax after taking foot off of brake petal. I thought the caliper was froze and replaced it with a new one only to have the same problem.
The piston can be pushed back about a 1/16th of an inch with a large screw driver but as soon as you remove the screwdriver the piston returns to the tight position applying pressure to the caliper.
The only way to relieve the brake fluid pressure is to crack open the bleeder screw. I realize that this is the prefered method to push the piston back into the caliper, however even after I push the piston by cracking open the bleeder screw and pump the piston back out I have the smae problem. The piston will not relax.
There is not a code set that shows by the ABS light on the warning lights.
Am I looking at problems with the ABS unit?
Any help.

Thanks, Jim
 
Sponsored Links
  #2  
Old 05-16-05, 06:22 AM
carguyinva's Avatar
Member
Join Date: Nov 2003
Location: Shenandoah Valley
Posts: 1,147
doesn't sound ABS related...

...rather a hydraulic problem. i'd bet the brake hose has collapsed inside. replace the brake hoses (both front ones) and see if your caliper releases then...if it does, take a razor blade and cut the old hose in two...straight down thru and you'll see what i'm talking about.
 
  #3  
Old 05-16-05, 06:42 AM
Member
Join Date: Aug 2003
Location: Barre,Vermont
Posts: 472
I am not positive about how your hydraulics are set up , but alot of older GM's had their base hydraulic circuits from the master cylinder set up diagonally. And you are saying the brakes diagonally from each other are staying applied. If that is the case, there's two hydraulic lines connected to the master cylinder. In between the line and the master there might be a proportioning valve. Try slackening the line where it goes into the prop. valve. If one doesn't do it, try the other one. If one frees the brake by doing this, it might mean the prop. valve or the master cylinder is failed.
 
  #4  
Old 05-18-05, 10:24 AM
Member
Thread Starter
Join Date: Oct 2003
Posts: 21
I have replaced the ruber hose to the front caliper, and that has not solved the problem, I don't find a proportioning valve.
Still the Right front and Left rear brakes are thght. The piston in the caliper does not relax. If I open the bleeder the piston will relax.
Could there be something wrong with the Anti-lock brake system that is causing this problem? There is no indication of a problem with the ABS via a warning light or any other visable indicator.

Any other thoughts on this problem would be greatly appreciated.

Thanks, Jim
 
  #5  
Old 05-18-05, 10:29 AM
carguyinva's Avatar
Member
Join Date: Nov 2003
Location: Shenandoah Valley
Posts: 1,147
the proportioning valve...

...probably screws directly into the master cylinder.

abs systems are pretty tight diagnostically speaking...normally it would set a code. in any case...you have to rule out basic hydraulic issues before jumping into a possible abs situation. it would be like having brain surgery for a headache...other stuff should be checked out first
 
  #6  
Old 05-30-05, 12:41 PM
Member
Thread Starter
Join Date: Oct 2003
Posts: 21
Master cylinder

After New calipers, new rubber brake hose, and having the ABS almost half disconected we discovered the the new master cylinder, that was but a few months old had failed in the first stage. It would build pressure but would not let it relax,
So the fix was to replace the "new" master cylinder with another "new" one. everything works fine now, actually better than it has ever worked since we have owned this car, as we are about the third owners.

Thanks, JIM
 
Reply

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 Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes