The Mercury garage put in a master cylinder because they told me that they could see a problem with it as I had just had new brake pads put in a month before that. My brakes gave out when on a trip.. the pedal when all the way to the floor then the second time stepping on the pedal it would work. I am bringing it back because the master cylinder wasn't the problem after all and they said that they never heard of a problem like this. I am really upset because I will never feel safe taking my car out of town again!!