1989 Ford Thunderbird brake pedal goes to floor

The power booster runs off vacuum, not air pressure. Either way, if this unit is bad, which I doubt, it won't make your pedal go to the floor. You have air in the brake system. The best way to remove that much air is with a pressure bleeder. A pressure bleeder attaches to the top of your master cylinder and forces fluid through the brake lines as you bleed them one at a time. You can try having someone pump and hold the pedal for you as you bleed each wheel, but it sounds like your master cylinder is airlocked.

so what i need to do? do i need to replace the m\c or bleed the brakes again ?????????

Did you bench bleed the master before you installed it?

yes, i did bench bleed the master and bleed each wheel afterwards. so the only thing i can think of is that, i either didn't bench bleed right, or maybe the m/c is defective and need to return it. its under warranty or let a shop fix it what's your expert opinion... thank you in advance

It could possibly be a bad master, but it is definately an air problem. It's your call to take it in and have it checked out. They will probably have a pressure bleeder which will make short work of bleeding. Let me know.

hey James i replaced the master and pressure bleed the system with a home made bleeder it worked wonderful
no more problems thank you for your help.

I love it when a good plan comes together!!! A lot'a times when you have a lot of air in a brake system, you can't pump the pedal fast enough to move the air out. As you're trying to bleed, the air keeps moving up the line and never gets to the bleeders. My first pressure bleeder was homemade also. Now, think of the " pearl of wisdom" you can pass on to other people. Have a nice Christmas.