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Old 10-25-2008, 11:24 PM
Junior Member
Join Date: Mar 2006
Posts: 11
Default Power steering leak 200 ML320

Power steering leaks. Looks like below resevoir. There's o-ring between the pump and resevoir. I need instruction on how to replace the o-ring.
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Old 10-26-2008, 11:19 AM
Join Date: Aug 2008
Posts: 17
Default RE: Power steering leak 200 ML320

Hi Teal854t,

While I didn't have this particular problem, I had a power steering fluid leak and searches a couple of site for answers on where to check for the leak and how to repair the problem. One of the answers I found addressed your issue. You can search the forum at either www.mbworld.org or www.benzworld.org for the particular thread, but here is what I found and copied to a word file for my records as it relates to replacing the O-ring:

You have to drain the fluid from the reservoir first. I suck it out with a syringe until there was none. there is only one bolt that holds it very accessible, I think it was a 10mm. then you have to remove the return hose as well. then remove the clip that holds the reservoir to the p/s pump by wedging a screwdriver on the middle of the clip.to locate the clip very easy it is where the bottom part of the reservoir that connects it to the p/s pump. after you remove the clip slide out the reservoir locate the o-ring inside the bottom part of the reservoir where it connect to the p/s pump and replace it with the new o-ring. slide it in, replace the clip and the bolt as well as the return hose. fill it up with fluid and there start the engine until it is on operating temp and then turn your steering wheels left to right several times.

Again, I don't remember which site had the info or which member posted it, but a quick search on the sites I listed above should yield the original post. You should pay close attention to make sure no air is in the system. Turning the wheel from left to right several times after the fluid has been replaced should address this. Since this wasn't the problem I actually had, I can only pass on what I found, copied and kept for my records. I would search the other sites to get more detailed information.

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Old 10-26-2008, 12:21 PM
Join Date: Aug 2008
Posts: 17
Default RE: Power steering leak 200 ML320

Hi Teal854t,

I just happen to be on Benzworld.org and found a post to a thread made today that talked about the whine that usually accompanies power steering problems and repair. As stated before, you can search the forum yourself, but here is what I found and copied for my records:

Power Steering Noise Fixed [/align] [hr] I just wanted to share how I did it...My experience as an Aircraft Airframe & Power Plant Mechanic came in handy here.

Materials list:

New Reservoir
Two bottles of MD Power Steering Fluid
One Seal
One "C"clip
One Large Syringe with a vinyl tube connected to it


1) Siphon out old fluid using a large "CLEAR PLASTIC" syringe, I purchased from a Farm & Fleet store here locally, by attaching a hose to it and pulling back the syringe plunger. Using the syringe will come in handy later as I will explain.

2) Remove old reservoir, "C"clip and seal. Replace with new reservoir, "C" clip and seal. $81.00 from MB dealer.

3) Fill reservoir with new fluid.

4) Jack front end with floor jack and block or use jack stands to prevent inadvertent lowering off front end.

5) Here is the important / critical step everyone has missed: Turn ignition key two clicks as previously mentioned being careful as to NOT START THE VEHICLE. Proceed to rotate steering wheel clockwise and counterclockwise 10 full sets. That is clockwise and counterclockwise is one set. Get out of the vehicle and syphon out steering fluid using the syringe and discharge the syringe fluid into a discarded water bottle . Notice the bubbles? Aha! Now. Pour in more fresh steering fluid. Repeat the 10 sets CC/CCL cycles. Syphon out the steering fluid with the syringe and notice more bubbles in the syringe. Replace with fresh steering fluid and repeat cycles until all bubbles are gone and not seen in the syringe. This insures all bubbles from the system have been purged.

What I noticed is that during the system purge, the bubbles in the Power Steering fluid never dissipated . In other words the bubbles stay in suspension -you will see them - in the syringe tube as you remove the fluid. You must remove the fluid, (and bubbles), and replace with fresh "UN-Bubbled" fluid between steering wheel cycle sets. If you do not, all you will be doing is moving the bubbles along with the fluid back and forth within the system lines never really purging them from the system.

This process took me about 2 hours. The steering is as quiet and as smooth as ever.

Just a little more info. Hope it helps.


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Old 10-28-2008, 06:20 PM
Junior Member
Join Date: Mar 2006
Posts: 11
Default RE: Power steering leak 200 ML320

Thanks, I found the instruction at benzworld.org. Bought o-ring for $2 at the stealer and done in an hour.
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