Hyundai Repair: air flowing into power steering fluid makes whinning noise, hyundai santa fe, power steering rack

Question
i own a 2002 Hyundai Santa Fe. In November of 2006 my power steering fluid hose cracked leaking out most of the fluid. when i caught the problem it was too late, my power steering pump was damaged, and had to be replaced. now in May of 2007, I'm hearing the same whinning noise and my power steering fluid keeps topping out of the container after long drives.  my mechanic changed my power steering pump,(luckily under warranty) and told me if this doesnt work he thinks my power steering rack is damaged, but i don't know what to think. It's only been three days and the same problem has happened again.  need help please D.G  

Answer
First, I'd like to verify what you mean by "topping out."  Do you mean that the fluid level rises so high in the reservoir that it pushes out of the cap?  If not, please explain what this phrase means.

If you're getting air into the fluid, you should check for any restrictions in the lines and any leaks.  

At the very least, it sounds like your mechanic is guessing.  He believes the problem to be the rack since he's already replaced the pump.  Although it's possible he's correct, I have some concern that you'll be undergoing a lengthy trial-and-error process at your own expense.  Have the reservoir and lines been fully checked?  Is your fluid flow level proper?  Depending on the (re)manufacturer of the pump, I might even suspect that the pump was of low quality and be causing the entire issue.