Brakes

I have a 2001 Chevy prizm Lsi the brakes will not build up. I have changed front and back brakes, blew out lines, peplaced master cylinder with a new one. Mechanic used a buster and said that it worked fine but in the morning the peddle would not build up again. Says he has no idea what is wrong. please help

What I have done on extremely hard to bleed cars is to use an a/c vacuum pump. The way it’s done is to make an adaptor to seal on top of master cylinder. Make sure all the bleeders are closed. Bring fluid level in m/c to about half, the idea being to not suck brake fluid into vac pump. Attach adaptor to top of m/c, turn on pump. Let it run for 5 minutes and hopefully you get some stubborn air bubbles out of it. Good luck

the peddle would not build up again.

Could you give a description of build up again?

I believe he means the pedal will not build pressure.

I mean that when you press the brake peddle down it goes all the way to the floor and nothing happens.