I noticed my breaks on my van were getting loose. Then one day they went out. I mean pedal all the way to the floor and nothing. There was no break fluid in there so I had some put in, still nothing. I had the breaks bled all way around, still nothing. I then had a naster cylinder put on and still nothing. I don't know what's wrong...
My breaks have gone out and i dont know whats wrong... on 1990 Plymouth Grand Voyager
You should remove ALL 4 wheels and Brake drums if equipped to inspect for fluid leaks. If there are no visable external leaks, the master cylinder can be leaking into the power brake booster. You said the Master Cylinder has been replaced. Re-bleed the system, starting at the right rear wheel, left rear, right front and left front.