While returning from dinner last night, a bump in the asphalt resulted in a noise in the rear suspension that sounded like it was bottoming out. While I go at about 250 lbs., and the other fellow in the car also is about this weight, this car should not be overloaded. the car has 126k miles, but is in great shape.

Second item: the idle sits at about 950 rpm, with nothing on, in park. I believe 650 rpm is the desired value. Any ideas on the cause and solution? I have seen some posts on the idle control relay(?) and air valve. Perhaps someone could shed some light.
Thanks in advance

Regarding the rear suspension noise, your car has ride leveling, there are a few things that could cause the suspension to bottom out:

1) The ride leveling valve is bad

2) The hydrallic pump is bad

3) The accumulators are bad. Should be changed every 60K miles

4) The shocks are bad

5) The level is set too low at the leveling valve. Easy to reset.

The first thing that I would check is leak. If nothing is leaking and the accumulators are new then it is probably a simple ride height adjustment. Good luck.

Thanks, I will hunt for some leaks and I am betting the parts are overdue for the 60k replacement. Does mercedesshop stock them? Is it a DIY project to swap them out? Keeping in mind I have done rotors and pads on the front, and had no problem diving into that. I do NOT have a lift though. Thanks for the help!

The accumulators really should be done on a lift. They are quite a ways inside and up into the rear.

Another part that can give a bottoming out sense is the mounts at the top of the struts.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

more info: when I purchased the car, the reservoir under the hood was wery low. I there a bleeding provision in the system, if air has been introduced?

The system should self-bleed, but it may not self-prime. I haven't had much problem with the load leveling systems, but have had the same pump not prime on many full hydraulic cars like the 6.9 and 500SEL.

Fill it up and see if it works. The way to tell qualitatively is to have three people get in the rear then start it up and it shoul lift the car back to where it started.

I will take a shot at that tonight, (if I can find three friends). I have never noticed the car moving upon starting EVER !
Thanks

no movement, with three guys in the car. any advise on priming this pump? Also, any word on the high idle speed? 1000 rpm?
Thanks