soft brakes on 308d

[schmiteysmith]

Hello anybody, I've just changed my vacuum pump servo and master brake cylinder and still have a soft pedal. I've bled the system at least 4 times, there is new fluid at the bleed screws. I discovered an air leak at the servo and rectified this. I also bled the master cylinder. Any ideas. Should fluid pump back into the reservoir when the brake pedal is depressed?.

 

[television]

The master cylinders are twin (tandem) if one piston seal has gone the pedal travel will increase and feel very soft. This could also account for the going back into the tank, well that is the way that I see it.

 

[schmiteysmith]

brakes still soft

Hello Mr Television. I've changed the master cylinder grommets and there is a build up of pressure, in the reservoir causing it to leak at the servo end, the master cylinder is new. Could a new one be faulty?.

 

[television]

Just notoíced that the master cylinder was new.

Place you foot on the brake pedal and start it up, and the pedal should go down much further, this will test that the servo is working

 

[schmiteysmith]

Hello again. I talked to a mercedes engineer, who had an idea that one of the brake cylinders may be stuck, which could cause the fluid to blow back into the reservoir. I will also try taking the equalisation valve apart and see if that's blocked. This is a weird fault, with no obvious answers. Stay tuned.