Diagnosing Brake Problems?

[TA-litte ruff]

Hello, new to this forum.

I have a 1980 trans am, which hasn't been on the road since 2015 and has been in my garage since 2021.

I'm trying to get the brakes working again; they worked when I drove it into the garage, but they don't work now.

Power brakes, Drums in the back, discs up front.

I'm unsure where to start; I guess I could start throwing parts at it, but I would like to pinpoint the problem.

I replaced the rusted lines and hoses, filled the master cylinder, and started pumping.

After pumping until my leg gave out, I never seemed to get any fluid to the drums or calipers, and the pedal still to the floor.

I do not see any leaks, and the master cylinder is still full.

It has to be the master cylinder, proportioning valve, or booster.

Do you have any suggestions on diagnosing these three components, or should I replace one at a time until I get some fluid into the lines?

Thanks!

 

[Knightrider189]

If your brakes are on the floor and you are not getting any fluid, I will start by replacing the master cylinder.

Also, the rubber lines going to the front calipers will collapse inside the hose if they are old, and you won’t get any fluid thru it.

Please keep us posted on what you find.


1989 Pontiac Formula Firebird, 5.7, all OEM

 

[TA-litte ruff]

I was going to pick up a master cylinder this weekend, but thinking about it some more.

I only tried to bleed the rear on the last attempt and got nothing.

Plenty of Google searches lead me to believe I may have tripped the proportional valve when my rear lens was bad but I'm unsure how to untrip it.