1999 Pontiac Grand Am, brakes are spongy?

[taewing509]

I have a 1999 Pontiac Grand Am SE, V6. My Brakes are spongy, to stop the car my brake pedal goes almost to the floor. We have bled the breaks 4 times and it fixes the problem for maybe 12 hours but the next morning i get into my car they are back to the way they were before, we also replaced the master cylindar and still having the same problem. we arent loosing any fluid, and unlike before replacing the master cylindar the brake fluis would be above the max line until we bleed them. The only thing the mechanic we had check it said was that the back breaks needed to be aligned. Is this true? if so how can we do this?

 

[melsg5]

does the car have drum brakes in the rear? If so they would need to be adjusted. There is a slot in the back of the brake splash shield where you can insert a screwdriver and adjust the star wheel, again this is only for a car with rear drum brakes You are sure there are no leaks anywhere including all the steel brakes lines and rubber hoses?