The power steering pump in my 2.5 contour makes a loud whining noise. Only after the car has sat for about a day and a half. It only makes the noise for about 30 sec to 1 min, but then reoccurs periodically. If the car has been driven within the last day it usually doesn't do it, and if the car sits for around a week it doesn't do it. I'm pretty sure that the pump is losing it's prime, but don't know if the pump is bad, or if a hose is allowing air to seep into the system. Any suggestions? Ideas? Experience? Thanks