W163 ML55 AMG No Power steering when turning left - fixed

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Sep 5, 2003
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88 190e 2.0, 97 CLK 200, BMW 535i sport, BMW 540i touring
Hi All

I'm back into Mercedes ownership with my 2001 ML55 AMG, its an awesome machine but recently I had a problem where I lost power steering only when turning left, when turning right the PAS was fine. The fluid level was good and there was no air in the system, the pump was also good and there were no funny noises just no assistance when turning left.

I eventually found that it needed a new steering rack and apparently this is a common fault. There are two valves in the rack that allow fluid to flow left and right based on which way you are turning and one of these had gone so it only affected the steering one way. I replaced the rack along with the tie rods and ends and this solved my problem. If you're changing the rack you may as well change the tie rods and ends because they need taking off anyway.

I read up on a lot of posts before taking the plunge for an expensive part but I couldn't find any posts that exactly matched my symptoms so i thought I would post here in case anyone is having a similar issue.

I got a reconditioned rack from Kelly Bray Steering, the guys there were really helpful and in total after sending them my old one it cost me £250 including all postage which was much better than I had anticipated. Originally I thought I had a speed value which adjusted the amount of fluid in the rack based on the speed as this is what I had read on most of the US forums but it turned out I didn't have one, not sure if this is a US only thing on the ML55 or a factory option but if you can get underneath its easy to check which type you have, as it turned out with me it was the same rack as the standard one across the range. You should check though as yours may be different. There are two fluid pipes that enter the rack where it joins the column, if you have an electrical connector in this area you have a speed valve.

Hope this helps someone, I know how frustrating it can be with a problem like this! I didn't attempt it myself and the mechanic charged me 3 hrs labour although I think it was more like 5 hours for the job.
 

Pathfinder

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CLC 220 CDi Sport Diesel Year 2008
Good post, I'm sure it will be of use to others with the same car model and problem.
 

alexanderfoti

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Many thanks! You can find out if you have the speed senstive power steering valve if you have the "parameter steering" option.
 

theshark180

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Mercedes ML320 W163 Lpg converted
A very useful post. I have exactly the same symptoms on my 200 ML320 W163 which is now on its 3rd steering rack in 6 months.I presukme this is the same for this rack. I can only assume that when they have been refurbished this has been overlooked or that the valves are faulty after a short period of time after being fitted. I passed this info onto my garage which hopefully will eventually sort this!
Thanks
John
 

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