I have had a power steering fluid leak for about 6 months now. It has made a mess of my drive way. I have been trying to track down the leak but I was not able to see where it was originating from. All I knew was that it was coming from the pump/reservoir area. Every few weeks, I would have to fill with more power steering fluid. I put some dye in the reservoir but I was still not able to find the leak. It was not coming from the steering rack nor the hoses. All I knew was that it was coming from behind the reservoir so I preceded to remove it.

There are 3 torx bolts size T30 that is needed to remove the reservoir from the front. Once those are removed, there is C clip behind the reservoir that holds it into the power steering pump. Once that is removed, you can firmly pull the reservoir out without having to pull out the other hose and clamp. Be prepared to have the remaining power steering fluid leak out from the bottom of the reservoir. I looked at the rubber O ring seal and it seemed a little flat and worn form some reason. Having done this on a Sunday meant that I would not be able to get the O ring from the local MB parts counter. Well, I have been hoarding all those O rings that are used for the engine oil filter change. It fits perfectly on the male tube that goes into the reservoir. the difference between the O rings are that the one that is used for the power steering reservoir is a flat O ring and the one that I used from the oil filter is round. You do have to push firmly on the reservoir to get it seated. I got it in, bolted the reservoir back, put the C clip back (which was a pain) and so far, 3 week in , no leaks.

For installing the C clip, I would suggest that you tie a small string or twine to it because it will fall to the bottom air deflector a few times. You can cut it off later. Lucky for me, it didn't go lost in the engine compartment. After I tied the twine to it, it was easier to keep hold of. Pushing the C clip in was a task until I got a long flat head screwdriver and angled the rear of the screw driver towards that headlight and force the c clip in. You will probably not be able to push it in with your fingers as it is a very sturdy C clip.

I hope this helps someone.

 

its most likely your power steering seal aka o ring , 2 dollar part , 45 minutes labor, thats why you can't see it, if you go to mercedes they will till you the whole power steering reservoir needs to be changed out. 370 with part and labor.

 

Nice write up!

I did the job on my vehicle. Here's a nice video on the subject:

 

Great write up! Thanks for sharing.

 

Just wonder if you know what size c clamps are needed for the ml350? My husband lost it some where down in the engine and we have to finish repairing it tomorrow!

 

I put in the o-ring (o ring and reservoir bought from dealer) and felt the thing "click" back into place. I put the C-clip in without too much issue, and it's sitting where the guide-path is (like a channel on the plastic). But I've still got a leak while the car sits.
Did you all notice something that was easy to miss in there? I've got the star nut (in my E class it's just one) in properly snug (feel like I might crack the plastic if i go more).

Thanks for any guidance,

Ridwan

 

Blew the power steering line this morning. Anyone know the part number? It comes off the side of the pump, runs the the center of the radiator and then down to th front left corner

 

Reading this thread just in case I ever need to do the job. Thanks to all posting.

One trick I learned when you have reservoirs of any type, is to empty them before you pull them so that you don't make a big mess when you pull the hose. There are several ways to do that, but one of the easiest is to keep a turkey baster in your tool box. You suck the fluid out with it and dump it into a container. If you have a MityVac, that also works.

I do this with brake fluid especially so that you don't have to pump a full reservoir of fluid through the calipers. Speeds up the whole process.

Also, since the filter is not replaceable, it's a good idea to just replace the reservoir while you're in there, which is how you 'change' the filter.

 

I thiiiiink I have this problem right now. The PS fluid level went down pretty quick a few months ago. Filled it up then, and now is back down to below the minimum line on the dipstick. What clued me in is seeing an oil leak down the front/side of the block. It's starting high, so either a PS leak, or maybe from a cam sensor. I doubt that, as it just doesn't look to be coming from those. So I need to investigate the PS leak hypothesis a bit more. I like the ideas in the above video on how to test for the leak. I need to get under the truck and check it out more! As long as it's just that, looks like the o-ring fix is pretty straightforward. Hopefully not the lines.

 

most always caused by a hardened o-ring or a cracked reservoir. The o-ring is about $3.50 and the reservoir costs about $75 at a dealer. The tricky bit is levering the c-clip back on without dropping it.

 

Looks straightforward, other than that c-clip. Parts are in the mail, should be doing it this weekend.

 

Can you please explain how this C clip goes in properly? I am almost at the end of this job and I’m getting very frustrated.

 

With finesse and force.

It will slide on a lot easier if you tighten the reservoir bolts first so that the slots align.

 

bolts are on...this is the last step before I wrap up. Ok so force and finesse but do I use a Vice grip to hold on to the clip, or do I clip it on to the grooves and smash it in what a blunt object or do I keep dropping it into the engine bay hoping to never see it again? I’m not a mechanic so I need a lil more descriptive help

 

I used the eye end of a large adjustable wrench to lever it onto and over the pipe. One hand holding the clip, the other levering the wrench.

someone has to have done this is a less contortionist way than I did.

do not smash. You’ll crack the reservoir.

 

2010 GL550 with 130k miles.

I need this done asap. Dealer advised I needed a new power steering pump and reservoir.

I add fluid to the reservoir weekly. It is hard to turn the wheel while vehicle is not in motion..

I think I'm just going to order all parts from FCP Euro and have the dealership do the job.

 

Good luck finding a dealership that will allow you to bring parts.

fwiw I bought my o rings and reservoirs on the three cars I’ve done this jobber on from the....

local mb dealer parts counter

it was actually cheaper than fcp, and gennie MB to boot.

if you know swear words and are reasonably limber this job is one of the more frustrating diys, but it’ll save you a about a grand.

 

I've always brought my own parts to my local MB dealership. They installed my Arnott struts, all 4 corners. Thats literally the only aftermarket parts I've ever used though.. Any other parts I've purchased from FCP are genuine mercedes parts.

 

Fixing my friend's 2004 ML500 as a favor for them and have replaced the reservoir, the O ring AND the pump with all new parts, but still have a leak somewhere in the system that is rapidly losing fluid when left sitting. The engine bay is absolutely filthy with oil deposits and the chassis is also covered. Its near impossible to pinpoint the leak because of all the build up gunk. I have a ton of experience fixing cars, in fact this is one of the easier ones I've done. My question is, have people had and solved leaks previously in the system that were NOT reservoir, O ring or pump related? The supply hose is on tight and doesn't seem to be the culprit. Wondering if its perhaps the other longer hose that connects down to the steering column. Anyone?

 

this question belongs in the W163 forum, the pump sits on a different engine, but it’s similar enough to where I think we can take a wag at it:

You didn’t mention the circlip. This one comes off easy and is often lost as it goes spoioiong.
if you locate it, reinstalling it requires dexterous use of all three hands, some language or some leverage. If you’re experienced with cars, you would not characterize this as an easy job. At least it is not on the X164 maybe due to access issues that you don’t have in the w163. So the leak you’re describing sounds to me like the circlip is not on, or you have a holed hose on the pressure side.

 

Nope, not the cir-clip. I got that back on properly and its not leaking from that part of the pump/res connection. Yes its a PITA to reinstall but a nice little tap tap with a deadblow hammer and a pry bar gets it back on around the male connection. My next guess is the connection from the steering rack to the hose that runs up to the pump on the drivers side of the car. Is this a common leakage point? I remember reading something about some guys having the steering rack itself losing fluid?

 

I know you said the reservoir and O ring were on properly, but it might pay to check that the O ring is in the groove on the inlet to the pump and that it didn't move when you put the reservoir back on, and that the reservoir is pushed back all the way toward the pump. My experience was that the reservoir on my W164 needed some force to sit in place properly and that just sliding it on didn't push it into place far enough. Check the return pipe whilst you're there.

 

Found the leak…I’m guessing this will require a new steering rack? I’m not sure if there are seals missing or what but it’s dumping fluid lol.

 

replacing the pump and reservoir IMO was an easy job…but I’m coming from BMW S55 platform (F80 M3) where I just did a crank hub replacement, which is arguably the most complicated and lengthy part to replace. 25+ hour job that requires the engine to be re-timed, camshafts aligned, valve cover removed, a clutch alignment etc etc etc. so to me, this was very, very easy and straightforward. Having never worked on Mercedes before I replaced the pump and reservoir and installed a new accessory belt just by looking at it with my eyes, no YouTube or anything. Beside the point though.

 

I don’t have enough W163 experience to tell you how that rack comes out. it’s gonna be a dirty job for sure.