SLS Mystery
 

1989 560SEL

I conducted an experiment with my self leveling system (SLS) and did not get the results I expected. I jacked the car up and placed jack stands under trailing arms. I disconected the lever between the SLS valve and the sway bar. I then moved the lever to F and revved the engine. The fluid level in the reservior bottle dropped about 3-4 inches but the rear end of the car did not raise or lower any. I measured from the rear bumper. I put the lever back to L and fluid level in the reservior went back to where it was. I bleed the system at the valve several times during and ended up replacing about a quart with new MB fluid. The first time a bleed some fluid it was a bit foamy. Subsequent bleedings the fluid looked fine (but a darker brown color than the new fluid).

The system sure seems to be working normally but why don't I see the rear end of the car go up and down? Is my experiment flawed? The car rides ok and is not sagging in the rear. If anything, it might be a little high. I replaced the accumulators about a month ago but it looked like the old accumulators where in good condidtion. On one side the rubber boot around the piston is torn in two, the other side it is only torn a little. Neither is leaking fluid. I figure that this will eventually cause a problem.

I guess I should just put a bunch of weight in the trunk to confirm if the system is working or not.
~Dave

I'd feel a lot better if you drove the rear wheels up on ramps. There is a time delay from when the SLS valve is commanded to fill the struts. It can take a good 15 - 30 seconds for things to start moving.

http://v12uberalles.com/Rear_Struts.htm

on my wagon i did a similar test, but i raised the car on a drive on hoist, the wheels were still supporting the weight of the car, i disconnected the lever and moved it manually, the effect was pretty close to instentaneous up and down at idle. you may have to retry the test with the car on drive on ramps or something wlse that will allow you to safely get under the car and try the test.

How much should I expect to see the rear end move between the 'L' and the 'F' position on the valve?