2008 with power steering noises??

On Jan 3, replaced P/S pump and again on Mar. 28 put another in after could not bleed air sucessfully from system. Replaced the high pressure line on this last install. Have tried bleeding system with vacuum with engine running and turning wheels stop to stop as well as at another time bleeding under vacuum turning wheels stop to stop with engine off.

Have had no success using either method in stopping the whine noise. Checked the fluid and its up to proper level and no apparent air in system. Driver says there is no problem in turning, the power assist is working...just noisy. Open to any ideas on getting to bottom of this trouble.

Did you use a Napa pump? Are you sure the rack is not leaking from the end seals into the boots?

Did you use a Napa pump? Are you sure the rack is not leaking from the end seals into the boots?
We have a Mityvac 4000 vac pump. Checked all over the rack and the lines and all is dry. Even put the screw gear pipe clamps on the hose connection on the return line at the pump instead of the spring clamps to make an even tighter seal there.

The noises with this car eventually died down and then went away..totally weird, but hey I'll take it!

Now I got another Impala, a 2006 this time, same thing, no signs of leakage on the lines or rack, but installed another pump yesterday, and its back again today with same issues. I guess only thing left is to change out the rack, hate just guessing and throwing parts at something though..hoping it fixes the problem.

Note: Later found out a good method to finding out if your rack is leaking, is by raising the front end and turning the steering wheel stop to stop, engine off, while having the power steering reservoir under vacuum. If you lose vacuum at either end of the turns, this indicates the seals are leaking in the rack and needs changing