Replaced my power steering pump with a Used one (description said excellent condition) however when I put it in the pump seemed to make an incredibly loud whining noise just like my old one. except this new pump actually returned power to my steering where as the old pump was dwindling in power. When I did the repair I used the appropriate steering fluid after flushing the old system out.
Any Ideas on the reoccurring noise? Im wondering if I put my old one back in, but using the now correct fluid that ill have power back even with the old one.

 

The noise may be causd by air in the system. Purge the air out by turning the steereing wheel lock to lock several times.

 

Meh, already did that a lot :/