SLS suspension issue

[B500EWF]

Hello and nice to meet you all (this is my first post and thread on the board)

I recently became the owner of a 1995 MY W124 E500 imported from Japan. Since the car was purchased at auction, having a few issues was to be expected. One of those issues is with the rear SLS suspension, in that the car has a tendency to hop quite violently whenever driving over uneven spots such as speed bumps. More specifically, when passing over a 2-3 inches high speed bump, at low speed, the back of the car hops 2-3 times before stabilizing again. One important detail to specify here is that no noises such as clunking etc can be heard from the back - which leads me to at least hope that the cuprit is either the hydraulic accumulators or the hydraulic valve.

What do you guys think? Is it more likely to be caused by what I hope or is it a case of the dreaded strut failure?

Thank you very much in advance.

 

[gsxr]

Congrats on the new ride! Sounds like your accumulators (nitrogen spheres) may have failed. This usually also causes a very firm ride, and abnormally tall rear ride height. Try replacing those accumulators first, use OE (Genuine) or OEM (Corteco) only.

I assume your SLS hydrolegs are original / correct and not leaking (those are NLA, and NOS ones are $$$$$). The valve almost never fails, and would only cause "wrong" rear ride height, not poor suspension action / damping.

BTW, welcome to the forum!

 

[B500EWF]

Thank you so much for the reply. Since the parts (found Corteco, but will look for OE as well) aren't really that expensive, I think it wouldn't hurt to replace them anyway. One thing I forgot to specify: the car sat for quite a long time (I suspect at least 2-3 years, if not more, judging by the service records).

One confirmation: the SLS hydrolegs are what I incorrectly referred to as "struts", right? I haven't identified any leaks, but I will definitely check them again, as soon as I get access to an elevator. Also, since the car sat for so long, would it be a good idea to do a hydraulic liquid flush as well? I am guessing it's the same circuit and reservoir as for the power steering etc, right?

 

[gsxr]

One confirmation: the SLS hydrolegs are what I incorrectly referred to as "struts", right?

Correct! These are hydraulic rams with an internal rebound limiting spring. They have no fluid inside when removed from the car, and no pressure. The spheres are the remote pressure reservoir.

I haven't identified any leaks, but I will definitely check them again, as soon as I get access to an elevator.

The struts / hydrolegs rarely leak. The lower spherical joint can fail which will rattle when it's in really poor shape, and the foam stop buffer (hidden behind the accordion dust boot) may disintegrate over time, but at the moment there's no suitable method to replace or repair either of those items.

Also, since the car sat for so long, would it be a good idea to do a hydraulic liquid flush as well? I am guessing it's the same circuit and reservoir as for the power steering etc, right?

Yes, fresh fluid would not hurt. SLS utilizes a separate circuit from power steering, with a separate fluid reservoir on the passenger side of the engine compartment. SLS uses hydraulic fluid (ZH-M), not power steering fluid. PS and SLS share a "tandem" pump which has 2 separate, isolated fluid circuits. SLS is the front half of the pump and if the front radial seal leaks, you'll lose SLS fluid. Power steering leaks are almost always from the hoses (often above the pump, sometimes the S-hose to frame rail)... the pump itself should never leak PS fluid.