Technical Brake Problem Advice Please

[geordie chris]

Hi i have a 2.4td hlx the brakes have never been great seems like there is no spring in the pedal. They also hum (loud noise not grinding) when breaking at high speed. When you press the pedal a few times you get a noise like air releasing, the pedal gets hard and then moves down when you start the engine (which i think it is suppost to do).
So i was woundering could there be air in the system or is it a case of stripping the brakes and cleaning them.
Any ideas would be welcome and thankyou in advance.
Chris

 

[Renegade_8]

The pedal moving down when you start the engine just shows the servo is working. It should feel firm with the engine off and then without altering foot pressure it you will feel it sink down. You can look at the condition of the front discs without taking anything apart.