MBfinatic

So lately this has been coming more and more of a concern. I think it has to do with the electronic steering asist. It will somewhat intermit and different parts of the turn feel different. If im taking a sharp right turn the first couple of degrees feels normal and than all of a sudden it gets super loose like im steering a boat . A fellow member drove my car and noticed it immediately as well. Any ideas on what this could be?

johnand

Ok, I am going to ask a dumb question, but I assume you have checked the power steering fluid level? Might be a failing PS pump. Seem to have seen a few of these fail on these cars.

MBfinatic

Its ok I am kinda clue less on this issue. Yes and everything appered to be fine.

johnand

Your best course of action would be to hookup Star to it, and monitor pump pressure. I see your in VA. Are you near Trey? If so, maybe you can see if you can throw a few bucks his way and have him hookup his Star system and check it out.

jcnash

I had the same problem about a year or so ago. Its your steering rack....there are seals in the rack that are designed to hold at different steering pressure levels ie...a seal for a fixed range of psi. When that threshold is breached, another bigger (stronger) seal takes over.

Your low level seals are holding OK...but when your steering pressure crosses the threshold for that particular seal, the next bigger seal lets go and you have no assist.

You could re-build your rack, or buy a cheap used one off eBay. I chose the latter and problem solved!

MBfinatic

How much does that cost? Caused from massive handling test? Im not liking my Previous owner right now. Well at least im going to have everything perfect on the car when im done .

jcnash

LOL...it might be from a handling test...or more probably from the rubber seals wearing out and letting go.

New racks are in the thousands...but I found one off eBay for my coupe for $250 including shipping. Just make sure that you get the exact same rack as the one on your car (there are different racks for sport vs non-sport models etc).

Driving with a properly functioning rack with little to no play becomes a pleasure after driving about with a non-functioning one for a while. Good luck!

Gilgorm

I just traded my C230 Coupe. It had this same steering problem for over 7 years and MB couldn't figure it out. Back when it was under warranty MB replaced the steering pump and fluids but the effect was minimal. They suggested a new rack but I had to pay thousands for the parts and they were going to pay labour. There was no guarantee so I passed.
It never bothered me and I got used to it. It was less annoying in warm weather. It only happened during cornering and no one other than the driver noticed it.
GL

MBfinatic

So you cant just replace the seals? No way to repair the current rack? Sorry if thats a dumb question. yes I have noticed the warm weather as well.

jcnash

You can definitely replace the seals (by rebuilding the rack)....but might be more expensive than picking up a used rack off ebay.

BigBodyBenzC240

I had this issue and then some on my W203 but the pump was failing as well and was somehow shaving metal off into the fluid so my pump, lines, and rack all had metal shavings inside and my PS went out completely. Took it to a local shop and $1600 later I had a new pump, lines, and rack. MB dealership wanted $1600 just for the rack!! Maybe you can find a rack on ebay as stated above or find someone parting out and get it for cheap either way. Good luck!

1st lite

Have a look at this website for steering racks: www.mercedessteering.com
Not sure how good their product is as I don't need a new or rebuilt steering rack. Not yet anyways. The prices look fairly reasonable. If you do actually need one, make sure you order the correct part. There are different racks for "4 matics" and "non 4 matics", speed sensitive, etc. Good luck.

ggms16

I would definitely go with a new or rebuilt rack...

jkowtko

The poster said that the steering started out firm and then got easy. If a pressure seal was giving out, wouldn't the symptom be opposite?

Before you start replacing expensive parts, I suggest you suck out a bit of PS fluid with a straw or clear tubing and look at its color. If it's not a light clear green color (Pentosin/Febi CHF 11s) then you may have either dirty fluid or the wrong fluid in the car. Other threads have indicated that these steering systems are very sensitive to the type and condition of the hydraulic fluid. I recently flushed the fluid on my car and got rid of a nasty shuddering problem.

So I suggest you check the fluid condition and consider flushing your fluid before replacing hard components.

MBfinatic

hmm I will try that. Its not a terrible problem would deffinitly prevent me from taking it to the track .

MaliaWrighting

My daughter thought I was just having an anxiety attack, but my C300 is giving me similar issues. I have took it to the shop and they told me I needed a wheel alignment. I have checked for recalls and I believe it is the Steering rack and pinion, and it might also be associated with an electric issues. When I am on the freeway it and I'm driving straight the car goes to the right and left and the steering wheel is loose, it almost feels is if I'm going to crash the car. It is really scary. I have contacted Mercedes dealership a few times and my car has been in the shop twice already. I never want a Mercedes. Every time I get on the freeway my heart starts beating because I constantly have the same issue. Even when I'm driving on an uneven pavement road. I have to continue to brake because it feels as if the car is going to loose control.

jkowtko

First thing, rule out the tires ... in my experience worn tires seem to cause all kinds of nasty behavior with the front suspension, making you think the front wheel bearings are shot, needs alignment, bad struts, etc. so if your front tires are old or worn you should consider replacing them first and see if it helps. I have eliminated the "need" for a front suspension overhaul more than once just by getting new tires.

Next thing, check steering rack bushings for play, especially if the car drifts left or right based on where you are relative to the crown in the road. On my W203 these bushings were giving no more than 1mm and it still made the car wander quite a bit on the freeway. Replaced the rack bushings and that all went away.

Also look at sway bar links to see if they have play in them. You'll need to have someone rock the car while you look at them underneath. These are relatively easy to replace with the front of the car on jack stands and the front tires off. You may even be able to replace them with the front wheels up on ramps.

If your C300 is rear wheel drive, these cars have a pretty awesome front suspension, the 3-point link design (strut & two control arms) is the best of any car I've owned for ride and handling ... so at this point you need to look at replacing the control arms whose rubber will start to give after 7-8 years, and potentially the struts.

If your car is 4WD then it has the front wishbone suspension and drive axles, which are a completely different design ... at that point I would look at all the joints involved.

===

Considering you've brought this to the dealership twice and they haven't figured it out, I would lean towards tires and rack bushings as those may be harder to diagnose with the car up on a lift in their shop.

-- John