Need Tech help on scary Brake problem
My 560SL has developed a scary problem with the brakes. Normally when I step on the brakes, the peddle feels firm and only goes down an inch or 2 and brings the car to a smooth even stop. Lately the brakes seem to have a mind of their own and sometimes the peddle will go almost all the way to the floor before it builds up pressure. It always stops OK but I never know if it's going to catch at the top or bottom of the range. There doesn't seem to be a pattern to when this will happen. Sometimes when I first start the car , sometimes not until I have driven a while, and it will switch back and forth while driving in traffic. When the peddle goes to the floor, I have tried pumping the brakes to see if it will build up pressure but it doesn't make a difference. When they are firm at the top of the range I have tried to keep applying a lot of pressure with my foot to see if there is any leak down and there is not. .... Master Cylinder??Brake Booster??? Vaccume leak??? Any Ideas Thanks in advance...