Brake master cyclinder failure??????

Hi to all anyone with any brake knowlege will be greatly received.

Ive got a 300tdi disco 1 1995 and the brakes have been binding on a bit and then sunday after a long inlcine once i was on the level again i had some proper brake fade and lost all braking ability.

I thought it was the calipers, so today i took them apart and the pistons as i thought were not letting off and were stuck in position. I have taken them apart and cleaned them so now they work fine. with taking them apart i also pumped the old fluidd out as i poured loads of new stuff in so when i did bleed the air out clean new fluid came through. I also put new pads on while i was there.

I beld the system so that there was no air left in it and the brake pedal was firm. I did this with the engine off and all was fine. As soon as i switched the engine on the pressure faded away from the pedal and it travels straight to the floor (as if the brakes have faded). If I turn the engine off and pump the pedal it goes hard as it should and then put my foot on the brake and turn the engine on the pedal just looses all the pressure and sinks.

What i need to know is dooes this sound like the master cyclinder? or is it poss the servo? I have seen some service kits for them about is it best to get one of those or replace the whole unit? If the service kit is best does anyone know how hard it is to do it? and if poss where is best to get one??

Thanks in advance

Gareth

servo obviously working ,possible master cylinder but would check theres no air left as servo will show up air ,your foot on its own wont,are you sure pistons arent getting some air in

It's common on old vehicles after bleeding brakes buy pushing the pedal to the floor the upper end of the master cylinder operating rod which is never used so could be corroded (rusty) will pass through the master cylinder seals and destroys the lip of the seal, this may have happened but there may be just air still in the system.

Thanks for the help guys

I've looked into prices etc and it looks as though I'm going to just get a new master cylinder it looks alot easier and a lot less hassle just to replace it