Another stumper for me, which actually is not very hard. Today when starting the car, the brake pedal went to the floor, and there was virtually no, if any, working of the brake shoes to stop the car. I checked the master cylinder and it was virtually empty. I had the brake booster replaced two months ago. The worksheet shows the technician bled the brakes. I did think they were a bit spongy yesterday. They failed today, luckily in the garage. I have paperwork that indicates all of the brake cylinders were replaced about 2000 miles (long before I acquired the car). I filled up the master cylinder with brake fluid, started the car, and pumped the brakes about 6 times, and they firmed right up. I tried a couple little test stops and the brakes worked as they should. I am going to get it to a repair place to look the entire system over, but I was curious just where could the brake fluid go? I do not see anything around the wheels, in the engine compartment, or under the car that looks like brake fluid dripping. Any thoughts?