GU 2.8TD Brake issue

[Rickie3]

G,day all, ive recently purchased a 99 GU 2.8 TD patrol wagon, I have a brake issue, the pedal is very spongy, ive bled the lines and no air was present, when car isnt running pump the brakes and they go nice and hard, I start the bus and if I hold my foot on the pedal it slowly creeps to the floor, all disc pads are good, could I have a faulty brake booster? and does the booster have a one way valve, any advise would be appreciated thanks

[BigRAWesty]

Guessing it is vacuum assisted?
If so pull the small rubber hose Off the big black thing between the firewall and brake master and with engine running check for a nice vacuum.
It should be reasonably strong, and noticeable..
If not chase the joins back to the vacuume pump piece by piece until you get a good suction then try find the leak in the weak section..

[the ferret]

The pedal will go hard without engine running.
If pedal creeps, you have faulty master cylinder, have you bled the system starting from the furtherest wheel to the closest?
nothing to do with vacuum will cause creep.
Cheers, the ferret.

[Rickie3]

The pedal will go hard without engine running.
If pedal creeps, you have faulty master cylinder, have you bled the system starting from the furtherest wheel to the closest?
nothing to do with vacuum will cause creep.
Cheers, the ferret.
Yes bled the system from furthest wheel to closest, I believe it to be the master cylinder, i'm not a fan of honing and replacing seals, so i'll just buy a new unit, thanks for your help people