My car started making a moaning/friction kind of noise when driving home from work one day, started quiet but within 5 mins it was very loud and worse when turning the steering wheel. Got home and noticed it was leaking power steering fluid from the pump area and looked like it'd been coming out iof the reservoir cap.

Bought a second hand unit and just fitted it, started up the car and topped up the reservoir (nowhere near what cam out when I changed the pump), turned the steering wheel back and forth expecting the fluid to disappear from the reservoir and to keep having to top it up but it didn't move.

Put the cap on and drove it down the street and back (still with the original noise) opened the bonnet and the steering fluid leaking out of the top of the reservoir, why is this?