Brake pedal goes to floor

[67stang/sable]

Hi Everyone, I have a 94 sable and the brake pedal goes to floor. I bleed the brakes and it seemed fine but when i started the car and put my foot on the pedal it went to the floor and made a hissing sound and when I looked at the fluid it was almost empty. I checked everything when brakes were bled and there is no leaks anywhere I can see. Had car on stands and all tires removed. My problem is where is the fluid going And Is the master cylinder bad or something else. Any Help Would Greatly Appreciated. Thank You In Advance

[65comet]

There is a leak somewhere. Start under the dash to see if the fluid is coming back in from the master cylinder push rod. Sometimes it is hard to see that leak when it is going down under the carpet. If not there, then follow each brake line, paying careful attention to the points where it may be rubbing against something else. If you have rear drum brakes, the leak could be inside the drums. The fluid won't evaporate, you just have to find the wet spot. Have someone else press on the brake pedal. A leak will usually make a hissing/spraying noise to help locate it.