What can damage a brake line and cause a leak? I found that if I pumped the brakes to the floor they would go back to normal: on the first pedal stroke very little braking power, on the second one decent braking power, and the third back to normal. could it be master cylinder or brake booster, but how do i know which it is? He replaced the master cylinder, replaced my fluid, and … The brake pedal felt fine before I did the work. Sometimes it's old age, but in every case I've seen, it was a master cylinder that had gone bad, leaking brake fluid into the booster. Air in the brake line(s) is the most common cause of a soft/spongy brake pedal. There are no leaks. The problem occurs when the brake pedal is released at which time suction is introduced to the system while the pedal is returning to its normal position. The pedal is hard when the engine is off and extremely soft when running. no brakes, no visable leaks. My '07 Ford Focus started having a spongy brake pedal a week or two ago and it’s becoming a bit of a diagnosis nightmare. I'm going to assume that the brake fluid has never been flushed, as that is not a common maintenance procedure. It sounds like you have some air in the system. Fluid level was fine, and there were no apparent leaks otherwise. Good morning, I have a 2001 Ford Taurus. The master cylinder is the usual suspect due to the internal seals having failed. Pads, shoes, and rotors are fine. iv searched for leaks on all 4 wheels and traced the brake lines for leaks. Air in the brake lines could be due to a leak or low brake fluid. I have noticed on the last couple of weeks that my brakes feel soft. This can usually be diagnosed when a somewhat soft pedal gets worse. This can be tested by a shop if you want to be sure. Common Causes of a Spongy or Soft Pedal: Brake fluid leaks; Worn out brake hoses; Air in the system; Contaminated brake fluid . I'm aware that there is probably air in the system somewhere, but I've bled through a significant amount of fluid with no bubbles coming out. Learn more about the most common brake issues and their solutions, here. Thu Dec 27, 2012 12:50 am. It's not like you have drum brakes in the back.....low pads wont do this on 4WDB. When brake fluid leaks out of holes in the lines, the fluid levels become too low to apply adequate force to the brake pads. Does your brake pedal feel a little bit soft or spongy? How To Diagnose a Spongy or Soft Brake Pedal. If the brakes are soft or spongy, this is a good time to change or flush the brake fluid. You're... - … One of the most common causes of a spongy brake pedal is a brake line leak. Common Causes of a Spongy or Soft Pedal: Brake fluid leaks; Worn out brake hoses; Air in the system; Contaminated brake fluid . BMW, for instance has this as something you do every 24 months to ensure the brake fluid has as little moisture in it as bad.