Power Steering pump issue with noise
 

Hi, I am a new member and am having a problem with my 2010 F150 5.4. Initially, I had my rack and pinion replaced . The whining noise came back after 6 months. The Ford dealer has replaced the rack and the pump and hoses and pulleys. That didn't work so I bought a pump for the junk yard. It was out of a 2010 and had 40000 miles on it. They installed the pump and at first it was quiet. However, it is noisey again but not as bad. They claim they have replaced the fluid in the system. I am very frustrated and don't know what else to do. I am thinking that there is something left in the system that contaminates the pump each time. Any one have any ideas?

Thanks