Power steering noise in 2002 ML320

[s98swim]

Hello all, I have frequently been helped by the collective knowledge here and now have a problem...when I turn the wheel, in both directions, I get a whirl, i think it sounds like rubber squeling but not sure; at times, i feel a slight tension in the wheel with turning; happens in both r/l directions, seems to be worse with turning back to center; seems to get worse with car warmed up but not progressively louder with driving/speed, and it is present at a stop with turning the wheel...I took it to a mb shop and they replaced the fluid, replaced the reservoir...and after $345 (and replacing other stuff--about 170 for the p/s stuff), it does the EXACT same thing. What should I do at this point? The mb dealer here in nashville is horrible, I am a bit pissed that the mb shop did not drive the car after to assess the p/s and figure out that they did not fix the problem. In reading the posts, I suspect that it might be either the inner tie rod, or insufficient lubrication at the radial shaft sealing ring in the control head--atleast those problems sound like mine. Any thoughts on how much I should expect to pay.

It is an indep shop, Stuttgart South in Nashville. I am taking it back this week for them to look at. What should I say to the fact that they charged me for a service that I clearly did not need? Should I expect them to only charge me for parts? My 2002 ml320 is now off warranty and I cannot stand the service at MB of Nashville.

Thanks for the replies so far.

Any thoughts greatly appreciated!