CUTLASS Car Off Pedal Stiff Car ON Pedal builds no pressure brake light on...IM STUMPED

JD254

Not-quite-so-new-guy
Thread starter
Aug 1, 2018
19
3
Texas
I have 1986 Cutlass that brakes worked fine before i did the blazer spindle swap and installed the new calipers.the lines seem to be bled fine no issues there i have replaced the master cylinder and the brake booster and the same issue when the car is off some pressure builds up when brake pedal pumps when car is turned on pedal is a mushy as mashed potatoes for a gerber baby. Just curious what else i should look into. No visible leaks checked all hoses and cylinders. at this point its gotta be something simple i would think no about to replace proportioning valve just on a whim the same way i did the booster the master cylinder was visibly leaking. Ive never had issues bleeding any of my other older gm 80s vehicles but this one is being quite difficult. Thanks in advance.
 

ELCAM

G-Body Guru
Jun 19, 2021
804
93
Bleeding the master cylinder is very important. I use clear tubing to see when it quits showing the air bubbles.

Bleeding the master cylinder on the bench, you can do it on the car too.
MC1.jpg
 
  • Like
Reactions: 2 users

JD254

Not-quite-so-new-guy
Thread starter
Aug 1, 2018
19
3
Texas
Bleeding the master cylinder is very important. I use clear tubing to see when it quits showing the air bubbles.

Bleeding the master cylinder on the bench, you can do it on the car too.
View attachment 210446
I did bleed master cylinder before booking lines back up am tips or tricks you can recommend or anything else I can check that I may be overlooking
 

ELCAM

G-Body Guru
Jun 19, 2021
804
93
If there is air at a higher elevation than the bleeder screws you can not get it out with the bleeder screws. Use the fittings to bleed the master cylinder then go to the proportioning valve and do it there, inlet first, outlet tubes next. Then bleed the wheels.
 
  • Like
Reactions: 1 user

Built6spdMCSS

Comic Book Super Hero
Jun 15, 2012
2,708
113
Florida Beach
What do you recommend best way to get air out I’ve had a buddy come help tried speed bleeders
I gravity bled mine, then each corner with farthest to closest. Installed the Disc/Disc Valve when I did my C5Z06 Front Brakes and that's how I bled it all out.
 
  • Like
Reactions: 1 user

JD254

Not-quite-so-new-guy
Thread starter
Aug 1, 2018
19
3
Texas
If there is air at a higher elevation than the bleeder screws you can not get it out with the bleeder screws. Use the fittings to bleed the master cylinder then go to the proportioning valve and do it there, inlet first, outlet tubes next. Then bleed the wheels.
Bleed the prop valve
 

JD254

Not-quite-so-new-guy
Thread starter
Aug 1, 2018
19
3
Texas
I gravity bled mine, then each corner with farthest to closest. Installed the Disc/Disc Valve when I did my C5Z06 Front Brakes and that's how I bled it all out.
i think i may need to try the gravity bleed because lines seem clear but when car on to the floor. i will try to find write up on it unless its easy to explain
 

JD254

Not-quite-so-new-guy
Thread starter
Aug 1, 2018
19
3
Texas
If there is air at a higher elevation than the bleeder screws you can not get it out with the bleeder screws. Use the fittings to bleed the master cylinder then go to the proportioning valve and do it there, inlet first, outlet tubes next. Then bleed the wheels.
sorry i meant for that to be like a question how do i bleed prop valve???
 

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact Admin@GBodyForum.com for info on becoming a sponsor