DISCO’S FALLING BRAKE PEDAL
QI have changed all four brake discs on my 300Tdi Discovery 1 and bled the system thoroughly from each wheel several times. The pedal seems fine after bleeding the brakes, but after I drive a short distance, the pedal drops (not to the floor – I can still push it down) and becomes spongy. I’m bleeding them according to the book, starting with the wheel furthest from the master cylinder and finishing with the nearest. Am I missing something? The master cylinder was renewed four months ago. Hoses and pipes look okay; no leaks. Roger Benson, South Wales
AFirstly, double check all the calipers, pipes and joints for leaks. Then clamp off the flexi hoses to check that the master cylinder is holding pressure. By pressing the brake you should feel a firm pedal. If not, and pressure is being lost, the master cylinder could be faulty. If no fault is found, then try each wheel caliper in turn by locking off the other three using brake hose clamps. Also worth trying, is a pressure bleeding system. Lastly, check the pipes to the servo for any leaks.