Power Steering Noise even after new parts

[ModedLS]

1994 LS400. 152K. It happens more in the colder weather, but when i turn my car on this annoying, unbearable noise begins and worsens when i turn my wheel. Ive been to lexus twice already. They have replaced the rack and pinion and the power steering pump. the noise is still there! i know the techs at my dealership arent too bright because everytime i get a part repaired or replaced i have to go back a second time. Any of you guys have any ideas as to what the noise is and where its coming from? let me know im goin back to the delaership a third time on tuesday.
Thanks

 

[Peewee]

Is it a groaning or a squealing?

And its time to find a new place to get your car repaired.

 

[jibbby]

Sounds like your low on fluid...Could you have a leak...

 

[SCV8]

There's a filter in the system, a screen, I've been told, I would want to make sure any crud from a previous burned up pump hasn't plugged everything up.

You'll need a drawing of the system to be sure, but I believe the screen is in the rack.