1994 S500 won't self level but rides great.
 

My S500 rides like a cloud but I have noticed that it does not self level. The fluid level is normal and it's not bouncy. I added about 500 to 600 lbs in the trunk and it lowered about 3 inches and never came back up over 20 min of watching it with it idleing. I removed the weight and it went back up to normal. Any idea? It does not have ADS and the auto leveling arm is attached to sway bar. How will I know if the pump is bad. I've had it up on the lift to remove all weight and it still sits normal so I think the check valve is working. I have read that people have done that and it lowered the car. :confused:

How old are the air cells(accumulators)? Have they ever been replaced?

They have never been changed to my knowledge but they don't show symptoms of being bad. No bounce and smooth ride. I also cracked a line and fluid was rather clean with no foaming.

I had the same condition in my wagon. I changed the accumulators and it fixed the problem.

So your car had a great ride, didnt bounce, had no foamy oil but wouldnt self level when adding weight, you changed the accumulators and all was well?

Yes, that is correct. I tried adjusting the rod. It would go up and down manually when I disconnected the adjusting rod, but not with a load. Eventually the ride got hard and when the accumulators were replaced, the SLS started functioning as designed.