So the brakes have been progressively getting worse and I had noticed the fluid had been getting low. The master cylinder was on it's way out so I thought this was the problem so I replaced it. Installed it on the weekend and bled the system and the rear slave cylinder started leaking. So today I buy another. They only came as a pair. So tonight I put the new one in and proceed to bleed the system and get all the air out. Only to find that the peddle goes to the floor. If u pump it it gets hard and stays hard. But drive a bit and it goes to the floor again. What could this be?