Before Christmas, a slave cylinder on a rear wheel failed and drained all the brake fluid out of the car. I found this out the hard way - by having the pedal go to the floor! The garage replaced the failed slave, and the other rear slave as it was leaking and replaced the fouled brake shoes. Driving the car home, I noticed excess travel on the pedal, and a hissing noise from under the dash, whenever the pedal was depressed. The garage had a look and said the auto-adjuster hadn't taken up and it was much better for a few weeks. In the new year, I noticed that when the car had sat for a long time, i.e. over night, the pedal had excess travel, but would firm up again after one or two applications. The garage suggested the master cylinder seals may have been damaged when the pedal went to the floor, so I had it replaced. Now, I'm getting some excess travel again, and the hissing noise has returned.
I don't know much about brakes, but I do now that it seems to me as if the brakes are sometimes working at 100% and at others have greatly reduced efficiency. As it is a diesel and so uses a vacuum pump, I'm wondering if the pump is failing, and this is causing the loss of pressure.
Any ideas most welcome!
Simon