1990 Ford Mustang GT
Automatic
Miles 200K
Installed new master cylinder no leaks found, but when bleeding brakes no air comes out pedal is all in the way bottom.
Did you bench bleed the master cylinder? That's something that needs to be done before installing and bleeding the rest of the system.
If so, the new master could be defective and leaking internally. All too common these days. As I recall one of our people here, @justin-shepherd, had to buy 3 new OEM master cylinders for his old Pontiac before he got one that worked properly.
Bleeding the master cylinder's probably the most important step if you overlooked it, especially on an ABS car. You can accidentally pump air into the ABS module that then needs a professional to get it out. On my old Pontiac that Chuck mentioned, I bled the master before mounting all three, and brake fluid came out of the rear when two were bled -bad internal seals. It didn't really matter if I bled it before mounting it, because there's no ABS for the air to get caught up in. In that old boat, air just works its way out as you bleed the lines and takes a while. Bench bleeding alerts you to potential internal issues like that right away.
If you did bleed the master cylinder, there was no fluid coming out of the piston back and it's almost impossible to press the piston in with the bleeder caps on, the issue's probably past the master (make sure air is not bubbling in the reservoir, that's another internal issue and you need another master). Here's a video I found while doing my brake job. You can do an entire bleeding process with one person, which I did with the old Pontiac. All you need is a Coke bottle, a drill, some brake fluid and fuel line. I saved mine so I can do my next two brake jobs.
The only thing I would add to that brake bleeding tool is a check valve on the end if you're flushing out old fluid. (There are bleeder hoses you can buy with this.) Otherwise when you release the brake pedal dirty fluid will be pulled back in. Another way to avoid this would be with a helper who closes the bleeder screw before you release the pedal.
Good suggestion! I didn't think of that at the time. I went through over a gallon of DOT 3 in my fiasco, the fluid was clear long before I finished, lol. That fluid looked like Coca-Cola for a while