I have 96 f350 4X4 7.3. When I start it, it makes a loud squeeling sound. Seems like it might be comming from the vacuum pump. has anyone ever had that happen? is there a way to check it to see if it is that. Also while driving the sueeling sounds comes and goes. Seems to be getting worse. Could it be a bad pully on the Vacuum pump? There is also a slight rattle like something loose that is comming from the pump. Any info would be great. Thanks.