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Old 01-26-2002, 06:57 PM
Posts: n/a
Well, here's the update (this is for other DIYers so you can gain from my experiance) on my 1994 S500 rear suspension. I bought two "reservoirs" this is what MB calls the "nitrogen spheres" and installed them.

Using the car jack I jacked up the passenger side to the jacks max lift and placed a jack stand next to it under the rubber lift bumper, set the brake and chocked the front wheels, this gives plenty of room to crawl under the car on your back.

I located the softball sized sphere on the passenger side (I'll call that the right side) next to and just to the right of the differential.
With a number 10 metric open end wrench I cracked open the smaller line and let it bleed the hydraulic fluid out and caught it in a shoebox size plastic bin. If you stay well to the left of the differential you will not get sprayed. As the pressure came down I gradually loosened the fitting untill no more fluid came out and then completely loosened the fitting. [edited to add that per "jcyuhn" there is a better way to relieve pressure: "The nipple on the leveling valve is there to relieve pressure in the system before servicing it. Use a small diameter hose to collect the oil into a container."]
Next with a number 17 metric open end wrench I loosened the larger fitting and unscrewed it completely (no more fluid came out).
Next remove the three nuts holding the sphere to it's bracket with a number 10 metric open end wrench (a better tool would have been a ratcheting flat spanner) these nuts are a pain as there is no room and you have to flip the wrench every 1/8 turn to loosen them. These nuts appear to be some type of self locking nuts and have to be unscrewed all the way with a wrench. The sphere than just comes right out with no problem.

Refit the new sphere exactly opposite of removal, I left the plastic caps on until the sphere was in place to keep dirt out and put the nuts on first to hold the sphere to it's bracket, but ONLY by finger so that it can move around as you attach the hydraulic lines. Be careful not to cross thread the hydraulic lines, you should be able to finger tighten them almost home.

[I did not move the jack to replace the next sphere, there is plenty of room under the car as it is with the passenger side up]

Next I located the softball sized sphere on the driver side, on the 94' S500 it is just to the right (passenger side) and above the last exhaust resonator about 1 1/2 feet forward of the bumper. Same process as before except that no more fluid came out, apparently all of it bleed out when I replaced the other sphere.

To remove the sphere after it is completely loose you have to remove the two bolts holding the rubber exhaust pipe mounts at the very rear of the car and pull the exhaust pipe down 2 inches ONLY with one hand while extracting the sphere with the other hand. Refit the new sphere exactly opposite of removal.

Next I located the level valve to the drivers side and behind the differential, put a clear plastis tube over the bleed nipple on top of the valve place the other end in my plastic bin and opened the valve a couple of turns. At this point I decided to flush out as much of the old fluid as possible and to do this you MUST start the engine. I let the fluid flow from the bleed tube (it flows very slowly) until the level in the reservoir in the engine compartment was ALMOST empty..

{{By the way this is a good time to remove the filter which is in the reservoir by unscrewing the small return pipe and unscrewing the large nut on top of the reservoir where you fill it. When you pull the insert out you will see the quite large filter, which by the way has a magnet in it to catch metal dust.}}

..and then refilled the reservoir with fluid to the top. When the fluid coming out of the bleed tube was clear, I shut off the engine, crawled back under the car and tightened the bleed nipple.

Remove the jack and then fill the reservoir in the engine compartment to the proper level.

By the way, total new fluid used was 3 liters, I had gotten four just in case. Total time was about 2 hours.

Last edited by Jere; 02-01-2002 at 06:27 PM.
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