So I've never driven this car without this brake issue.
So the pedal feels very soft,and I gotta press it all the way down to get a small amount of braking power while going 5 MPH.
I noticed the master cylinder was leaking where it mates up to the booster,so I replaced the master cylinder. I'm 100% sure I bled all the air out of the new one. I'm also 100% sure I bled all the air out of the system. I made sure there were no bubbles in my bleeding hose. I bled a whole 32 ounce bottle through it making sure there were no bubbles left.
I have no idea what the problem can possibly be. The only thing that's improved by replacing the master cylinder is I don't have to keep filling it up with fluid.
What the actual hell is wrong? I've checked the check valve and it works. I'm told a bad booster wouldn't have symptoms like this,actually it'd have the opposite. There's no fluid leaking at my wheel cylinders to indicate they're bad.
I wanna pull my hair out cause of this damn thing.

 

So its not losing fluid at all anymore?

 

Did you bleed the master on a level plane on a workbench or after it was bolted to the booster? If you did it on the car there will still be air trapped in it.

 

I did it in a vise and it was level. I followed the bleeding instructions sense it's a step-bore master cylinder. At the end I couldn't push it in any more than 1/16 of an inch.

 

Correct

 

Rear drums?

 

If so adjust your parking brake cable

 

does your car have ABS?

 

possible things I have seen.

Master cylinder, abs bleed through, prop valve, drum adjustment, air, or a leak

 

It has rear drum brakes,yes.

 

It doesn't have ABS,so it can't be that. How can I test for a prop valve issue?

 

Where do I go to on the car to do that,and how?

 

Remove the rear wheels, remove the drum. Adjust the shoes with the adjuster on the bottom of the assembly until the drum goes back on and justjust touches the drum. If the shoes are loose and have too much slop, you will have no brakes just like you describe

 

Bouy 2 brass or steel screw in plugs that fit the MC. Remove lines and screw plugs in. Step on pedal, firm pedal your problem is downstream. Bad pedal you have MC problems. If the pedal is firm reconnect and isolate furthur down the line. You can clamp the rubber hoses one at a time to isolate or remove lines and cap them. you can remove hoses from caliper and use a bolt/nut with the copper washers to isolate. Or you can guess.

 

Well I figured out the engine isn't pulling a proper vacuum,and that's most likely the issue with the brakes.