Hey guys,

The steering feel on my (got it 4 weeks, 2 weeks driving now) W211 E55 AMG Wagon feels heavy and a bit stiff which I really don't like and don't think is correct.
So what I did was research this a bit and I found that it might be (SPS) Speed-sensitive power steering valve. So I ordered a new valve and replaced it just now. I'll keep it short, it was a pain to replace, it's mounted in a strange position so you can't see the bolts at all. Had to do by feel and a mirror I lent from my wife with my back on the floor :P But yaay got it done...

After removing the old SPS valve some fluid comes out of the rack and it looked like this:


Got a bit scared when I saw that. Looks to me like there is fluid in there that shouldn't be in there or that it is burned? If I didn't know I'd almost say it looks like normal oil.
I got new Pentosin / Fuchs CHF-11S as you can see behind in the picture, that is green...

So I did pour some of that CHF-11S in to refill it a bit. Started the car with the wheels from the ground, still on jack stands and I immediately hear the powersteering pump whining. At this point I'm just going from left to right with the wheel a dozen times hoping to clear out any air but it doesn't seem to stop the whining at all. Fluid level is good.
Before I did the valge change, it did not whine.
I got the car off jack stands and proceed to drive around my village to see how it behaves, it's still whining but I notice the steering is much much much lighter and better already, it feels now like it does in my my BMW E61 530i, so what I think is that indeed the SPS valve was broken but that maybe also it has either the wrong fluid and/or that the pump is also KIND OF broken? Now that the SPS valve is working it's more active when driving slowly and now we notice the broken pump whine because it's doing more? Is that possible to have it still do some work but also whine and be broken?
When I had the belt off 2 weeks earlier I could easily spin the power steering pump pulley, not sure if that is normal? It did also make a bit of a sound as well....

I'm not sure how to proceed here, does anyone have some opinion / advise for me? I was thinking:
1. Buy a new powersteering pump
2. remove old powersteering pump
3. replace fluid with CHF-11s pentosin/fuchs?

I'm a bit scared this could have damaged the steering rack or should that be fine?
Hope someone can give some advise

 

- You should not start the car, as this will introduce air into the system which is hard to evacuate later. The correct way is to turn the steering wheel several times lock to lock with the engine off and wheels in the air, this way air will move to the top of the reservior.
- Before replacing the pump, I highly recommend replacing the fluid reservoir as it has a filter/screen that gets clogged causing pump cavitation and the symptoms you described.
- If all else fails, do replace the pump

Good luck

 

Thanks Solo wing, I was under the impression I had to start the car and then go lock to lock. Dammit... Good information and noted, I will try this!
Have ordered up the reservoir and some more CHF-11s.
Hopefully that will sort it, that would be great!