dodgy brakes

[tarathedog]

Hello
My son has just bought a 1999 206 1.4i but it has excessive brake pedal travel.
The car still brakes and stops (but it is hard to lock the wheels) despite the travel when the engine is running, but the pedal has a 'conventional' feel when the engine is stopped i.e. when you pump the pedal and after the reserve vacuum has gone the pedal is hard right at the top. Start the engine with foot on pedal and it immediately sinks almost all the way down, pumping the pedal when the engine is running has no effect.
Fluid level is fine & I have bled the system (had to replace one if the rear slaves as the nipple sheared off.) I have checked the pads and shoes for wear and they all look good as do the disks and lining and the hand brake is adjusted correctly.
It doesnt have ABS
Anyone any ideas for the excessive travel

Thanks

[nige65]

Have you removed all old brake fluid and replaced with new ?

[tarathedog]

I have put a full 500ml bottle of fluid through with no change in the amount of pedal travel, so i dont think that the brake fluid is the problem