I have searched through quite a few threads on here and haven't been able to find any with my specific issue. About a month ago the steering in my ML550 started getting hard to turn. My wife drives it daily I drive it occasionally on the weekends when we go out. She said it started all of a sudden. There were no leaks, there was no noise from the pump, just harder to steer and the wheel does not return to center as normal. It has 160,000 miles on it and I have owned it for about 5 years, we bought it from a friend with 94,000 or so miles on the odometer. I have changed the PS pump, pressure and return hoses. I bled the system per the recommended process and there are no bubbles in the reservoir when running and the cap is off. Due to the age and mileage on the ML the pump and hoses seemed to make sense. Also, when changing the components, the fluid was black and smelled slightly burnt. After replacing the components, the hard steering stills exists but is slightly improved. We have continued to drive it and the steering hardness has not gotten worse.

The rack and pinion has been replaced prior to my buying the ML, it was purchased from Rockauto and installed by mechanic. My thought was to replace the rack again, but all of the issues I have read about with rack and pinion is that they leak not cause hard steering.

Any insight anyone may have on this issue would be appreciated.

 

yea get it diagnosed by someone who knows MB, preferably not a family or near family memeber

 

I had a similar problem years ago. It turned out to be the knuckle at the end of the steering column that had seized. It would be fine for the most part of each turn and then for maybe 90 degrees is would be as if the power steering wasn't functioning. I think there might be a bulletin on it from memory. I took it back to the dealer as it was under warranty. They laughed at me when I suggested the potential problem. When I picked it up they said "how did you know? We wouldn't have even thought to look there". If you've changed out everything else, might pay to check this out.

 

Thanks BlackML550 I will look into that. I have not replaced the rack yet so I will check the shaft joints 1st.

 

We are also experiencing a similar problem on my wife's 2010 ML350 Bluetec. It now has about 160k miles on it. We just got it back from the big emissions recall and my wife noticed that steering issue. It gets stiff occasionally when turning. No signs of leaks from the rack, PS pump doesn't make any noise or leak.

Has anybody replaced that steering shaft? Or have access to the procedure? It doesn't look like it's that hard to access, but I'm sure it's on there tight. Might be a better job for a pro, and could have them flush the PS fluid too..

 

I had a similar problem where for 90 degress of the turn, it would be stiff and hard to manage. It turned out to be the knuckle at the end of the steering column where it links to the rack. Everything else was OK and there was no need to change anything other than that part which was partially siezed.

 

I own a 2008 Mercedes ML550 AMG
and I need to replace the rack and pinion
can somebody tell me if I need to take down the differential to remove the rack?

 

i own a 2008 ML550 and i need to replace the rack and pinion, does anybody know if i have to take down the differential in order to remove the Rack and pinion?
thanks