I changed my Self Leveling Suspension accumulators out today. I was anticipating a grueling task, but although messy, I found it surprisingly simple to do. I ordered these accumulators from Mercedes Source and looked for a pictorial on how to do this, without luck. It's for this reason that I am posting some pictures and tips.

You'll see that the pictures that I took are after the fact, but with this simple procedure, I hope to just get you familiar with what you're going to be facing. The rest is pretty self-explanatory.

First, jack up the rear end of your vehicle and use proper jack stands to support it. Remember that you're messing with the system that adjusts the level of the rear end. MAKE SURE TO BRACE THE FRAME, NOT JUST THE WHEELS! I take no responsibility for your stupidity. If you bleed the system, your rear end can drop! Not good if you're under it.

Next, get under the car and bleed pressure from the system. Make sure you wear safety glasses for this. Fluid may be under pressure! To bleed pressure from the system, loosen the system bleeding nipple. This is located on the SLS valve just in front of the fuel tank, and can be found in picture #1. It's the nipple fitting that's now wet with hydraulic fluid. There is a rubber cover over the nipple that you will remove, and you will unscrew the fitting to release pressure. This requires an 11mm end wrench.

After there is no pressure, you will now focus on the accumulators. There are 3 11mm screws that hold the accumulators to the frame, 1 banjo fitting requiring a 17mm wrench, and one pressure fitting requiring an 11mm wrench. From here, it's pretty self explanatory. Just remove and replace the accumulators and tighten everything back up. I hope this proves useful for someone. Take a look at the pictures to understand what you're up against. Remember that you're going to have hydraulic fluid dripping down, so have something ready to catch it.

This job was surprisingly easy. The key is to do everything right .

Attached Thumbnails

       

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84 300td (Yes, a wagon)
"The Golden Dragon"
195k, 2nd owner
Lives in Redmond, WA

The procedure I used was to support the chassis with jackstands and let the rear suspension hang free. This took most of the pressure off the hydraulics and as a result, i only had to add half a liter when I was done.

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1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

The only thing I can add is thread the lines into the valve body before the accumulators. Cross threading the aluminum valve body is not good and is very easy to do. amhik?

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Brad
1981 300TD - daily driver
1963 Chevy II
2001 F-250 7.3 Power Stroke

There's no reason to mess with the lines at the valve body. The lines only have to be removed from the accumulators.
I'll add that my bleed screw on the valve body was frozen. I bled off the pressure by cracking a line fitting at an accumulator. Since you have to remove the line anyway, it saves a step.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Just wanted to do a followup after the test drive. For those of you who have an issue with rear suspension, or those who don't really know, you need to do this.

I didn't know what I was missing until I replaced these accumulators. What a difference this makes! It feels like a Cadillac in the rear now! Big, noticeable difference!

Also, I didn't think this would do anything for sag, but it has. The rear does not sag between parking at night and driving in the morning, and it seems to ride just a little higher. I don't have to wait 5-10 seconds anymore for the rear to come back up before driving.

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84 300td (Yes, a wagon)
"The Golden Dragon"
195k, 2nd owner
Lives in Redmond, WA

True. I had rebuilt the valve body at the same time though.

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Brad
1981 300TD - daily driver
1963 Chevy II
2001 F-250 7.3 Power Stroke

I just finished the test drive after following the steps here. Ride quality severely improved!! Pushing a thin popsicle stick into the old ones would go alllll the way in, very bad.

Discovered some other issues with my SLS. First, when I went to bleed the lines, nothing happened at all, no fluid and no movement or noise. At first I was reconsidering what was really wrong back there. But I decided to push forward and was glad I did. The fluid was very contaminated, looked like 50/50 motor oil and hydro fluid. Now, I'm off to order the SLS valve rebuild kit.

I think the pump is doing ok, for now. I cracked the return line and there was pulsing fluid flowing out. But, the fluid I see in the reservoir was a lot cleaner than what came out of the lines in the back. I'll have to revisit that SLS familiarization thread here to confirm, but maybe it's just creating two closed loops and the fluid stuck in the back slowly is diluted by motor oil.

Earlier this year the feed line from the pump was replaced and the system drained and a new filter installed.

Edit: I lost about a liter and had some on hand to replenish but the level stick show I was still good, both before and after the car was running. Maybe another sign of how a bad or leaking valve will isolate the lines in the back. I will try and adjust the ride height to see what happens.

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"Blessed are the cracked, for they shall let in the light." - Groucho Marx

I would add to the instructions to be aware of the washers: there should be 2 on each M10 banjo bolt, one on each side of the hose fitting. On my car it seems one washer is missing. I also found it hard to get the hard line in; I threaded it a little by hand (I thought) before bolting the accumulator up, but it pulled out. Only by taking off 2 of the supporting nuts could I jiggle things enough to get that line back in right.

I found a pair of the Corteco accumulators for $60/each from USP Motorsports.
Took a few weeks to arrive but they are the right part and waaaaaaay better price than anywhere else I could find.

Mine were and have been bad for a long time, as long as I owned the car (10 years plus). Ride didn't seem that bad, only symptom was that it would sag when shut down.

It rides amazing now. Really big improvement.
Easy job, big results.

1985 300TD wagon

Got a link?

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2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD