Steering Noise: Loud Groan when Turning Wheel
 

2006 Sonata GLS
141k miles

Listen to the following audio files:
Inside Cabin
Under PSrack

What you hear is the noise created every time we turn the steering wheel in either direction, lock-to-lock. To capture these two audio samples, I elevated the Sonata on jackstands and turned the wheel slowly back and forth. There is zero vibration, stiffness, or suspicious sensations felt in the steering wheel and when I push/pull the tires. I feel zero vibration when I rest my hand on the power steering housing and pinion-and-valve assemblies while inducing the noise.

The "Inside Cabin" clip is the actual sound--at actual volume--we hear inside the cabin. The "Under_PSrack" clip is the actual sound from the area immediately adjacent to the junction of the power steering housing and pinion-and-valve assemblies. Notice that "scraping" sound that follows the groan noise? That's the sound of fluid-churn inside the steering rack--a noise I've never heard from a rack before. (I checked the reservoir--it's full and there is no air froth.) Visually, the steering components appear okay: no wetness, bellows are intact, nothing loose.

This problem began four weeks ago with intermittent, though identical, noise inside the cabin. Now, the sound is constant and occurs regardless of ambient temperature, load/unloaded wheels, engine running or off. The noise is plainly coming from some steering component, but I cannot identify the specific source.

I welcome experienced Ideas, suggestions, add'l t'shooting steps to help me locate this problem.