Power Steering - can stop the whining!
 

After numerous forum searches, I can’t seem to find a definitive answer to the question – does the ML320 power steering reservoir have an internal filter or screen in the reservoir?

I recently replaced the failing o-ring between the reservoir and the power steering pump and can NOT get the wining noise to disappear. I’ve gone through several different air bleeding routines to insure there is no air in the PS system. I’ve jacked the front end of the SUV and moved the steering wheel from lock to lock at least 50 times over several days with the car started and stopped both. I’ve added the MB additive to reservoir. I insured there is the correct level of fluid and there are no visible leaks.

The most significant noise occurs when the engine is 1200+rpms while turning. There is hardly a noteworthy noise while turning or steering if the engine remains at a low rpm. The noise seems to have taken on a slight buzzing noise in addition to the whining while turning.

The ML320 has 120,000ish miles, so could a clogged screen or filter internal to the reservoir be causing my dilemma? Or should I begin searching for a replacement PS pump?

Thanks in advance for any thoughts on this matter.

it does have an internal filter. if you fluid id full but bubbly and full of air replace the resivoir. i have replaced many of them for noise

I wanted to post the results of changing the power steering reservoir to stop the “whining.” Yes, the reservoir replacement FIXED the problem! This forum once again is a wealth of knowledge!