The three nuts are 20 Nm. Note that these are self-locking nuts so MB wants you to replace them.

The small nut for the hydraulic line is 14 Nm and the larger one 30 Nm. You need some flare nut wrenches or claw foot flare (if you want to torque them).

 

Thanks Loubapache!
I will reuse the self locking nuts using blue Loc-Tite

 

Maybe you can do a writeup? These wagons are near a point that many will be replacing these accumulators.

 

If I have the time I will do a write-up and post pics. It's going to be 27degrees in Philly tomorrow so I want to minimize my time outside (I know, 27F is like summer weather in Michigan....)

 

Actually it is not too bad here in terms of temperature the last a few days but a lot of snow. I just finished installing a range hood duct and had to cut a hole through the wall outside and it was a bit cold.

No problem because it is a very straightforward procedure. The main thing is to be careful with these line nuts. Now replacing on a W124 wagon is a different story (the accumulators are much harder to access).

 

OK. Here the simple write-up.
It is a very straight forward procedure. There are three nuts holding the accumulator in place. I used an 10mm wrench to remove them. Prior to doing so, there are two fittings that carry fluid to and from the accumulator. A low pressure fitting (the larger 17mm nut one) and a high pressure fitting (the smaller 11mm one).
Step 1: I backed my vehicle on top of ramps instead of using jack stands so the rear shocks were somewhat compressed and the fluid was under pressure.
Step 2: Place a large pan under the accumulator to catch any fluid that leaks out.
Step 3: First undo the large low pressure fitting to drain fluid under pressure. If you undo the smaller high pressure fitting first, fluid will squirt all over the place.
Step 4: Once the low pressure fitting is loose, you can procede to loosen the high pressure fitting.
Step 5: Remove the 3 10mm nuts that hold the accumulator in place and remove the accumulator.
NOTE: On the passenger side, there is plenty of space to remove/install the accumulator. On the driver's side (pictured), the rear exhaust pipe is in the way so you have to maneuver the accumulator a bit for both removal and installation.
Step 6: Once they have been replaced, apply blue Loc-Tite to the threads of the bolts that hold the accumulator in place, refill the fluid container (next to the washer fluid) and go for a drive. Re-check fluid level an ensure it is between the MIN and MAX marks.
In my vehicle, the ride difference is negligible and I still feel a banging noise when going over bumps and both rear shocks are NOT leaking. The bushings seem fine so I'll have to keep experimenting until a cure is found.
If there are any questions, let me know.
I bought FEBI / BILSTEIN accumulators and paid $110 a piece shipped.

 

Thanks, Sergio. :thumbsup:

I will add this to the wagon sticky.

 

No problem. I would have liked to take more pictures but a) it was 25F and b) it's such a simple procedure that anyone can do it with minimal information.

 

Sergio, thanks for the writeup. :thumbsup:

Actually I was kind of holding my breath waiting for your report since I also have the banging noise in the rear when going over bumps that's driving me nuts, especially since I don't know where it's coming from.

I will need to inspect a little more I guess.

OTH, how much hydraulic fluid did you use?

Cheers

 

There is kind of a way to see if the accumulators are bad but they have to come off the car. Since you have taken them off, Sergio, and if you still have them, you can try it.

Stick a screwdriver gently into the big hole and see how far it goes in. If it goes all the way in, then for sure they are shot. If it hits the membrane somewhere, then there is a chance that it is not shot but you cannot conclude it is goo either because the leak could be around the membrane.

 

Where's the "big hole"? Thanks

 

I will try that Lou. I figured that they are bound to fail so I replaced them anyway...
As far as how much fluid I had to replace, about 1/2 qt. Not too bad.

 

Ok... ignorance post coming up...

What *are* the accumulators? What do they do, and is there a schematic, so I can begin to grok this?

 

The accumulators serve as the true "shock absorbers" for the self-leveling suspension. The struts (rams) in that system only serve the purpose of maintaining ride height.

Inside the accumulator, there is a diaphragm filled with pressurized N2 gas. The gas can be compresed by hydraulic fluid and expand on its own (a tug of war kind of thing) to achieve the shock absorbing.

It is like how a residential water tank works. Water can be pumped into the tank and the air bladder is compressed. When water is being used, the air bladder expands to push the water out.

 

Thanks! It's good to learn these things.

 

Bleeding the system

Well I just did the accumulators as well and it is a no brainer/caveman job though I did remove the wheels for easier access. The question I have is does one have to bleed the system after opening it up or will it just fill on its own?
I also changed the filter and topped up the fluid level.
The rear seats felt like you were riding on the axle so I hope this helps...Those shocks are ridiculously priced and appear to be dry...fingers crossed

 

The system is supposed to self-bleed. So after some driving over bumps and carry some weight in the cargo area, it should be good.

 

Thank you for precious info. Sir Lou and Sergio.
I am looking forward for a solution about banging noise problem...

 

The failed accumulators usually result in a spongey ride, then get very hard. the banging could be a failed strut bushing, mount, or swaybar link. The accumulators are usually around $100, the struts aroung $600 each. MB hydraulic oil is the suggested fluid, and the system is self bleeding.

 

What does "self bleeding" mean? Does it dump the excess fluid onto the road or does it self purge the air out of the system?

 

That means; you don't have to bleed the system like you do while replacing brake fluid.

 

When you remove the accumulator, it is the threaded larger hole where the largest nut attached to. You won't see it while still installed in the vehicle.

 

Hey Sergio,
Any updates on "banging noise" behind?

Fatih

 

Yes, replaced both accumulators and 1 qt of hydraulic fluid. No change.
Replaced both upper and lower shock absorber rubber mounts and another qt of hydraulic fluid and filter (confirmed no hydraulic leaks are present). No change.
The noise is coming from the underside, not the inside of the car. I guess bushings are next?
Last weeked I had my kids ride in the 3rd row seat for a trip. Banging noise was completely absent. I guess I need extra weight back there to solve this misterious problem....

 

I think we still need a straight solution.
I'm having exactly the same problem with my wagon.

Wait! What about the banging noise after the kids got out of the car? Still absent?

 

I did not drive the vehicle immediately after the kids got out of the car but did the following day. Noise came back. It "seems" that overall the noise is less now than prior to the rubber mount replacements but it could be psychological (wishful thinking). There is no doubt in my mind the vehicle was not designed this way nor it acted this way when new otherwise the previous owner would have taken it back to the dealer until it was resolved.

 

Wow, I can't believe I paid a dealership $550 for a "caveman" job. If only this thread were around two years ago when I had the work done.

Replacing the accumulators did not help my wagon either. However, I seem to have the banging worse on the drivers side.

The dealership told me the shock was damaged and that it would rattle, but it was safe to drive. It rattled once while taking an exit ramp at 60 mph, but recently it's been creaking when going slowly (2 mph) over curbs, etc.

If the new shock is $600, why does Autohausaz list part 102420 for $360?

There must be some way to stop this banging. It's been annoying me for 4 years now.