When do you know Rear SLS Shocks are dead?
 

My 300TE's rear end in the last 3 months has turned really, really heavy on speed bumps. It really "slams" down and sinks far down.
My SLS hasn't worked since I bought the car 4 years ago, it hasn't caused me any grief or issue so haven't really worried about it. Fluid level is still fine in the reservoir so its not leaking...

The general ride feels perfectly fine, it just seems to really dip low on speed bumps. It is not bouncy or anything and with 5 heavy people loaded up in the car I have no issues at all.

How do you tell when these type of shocks are worn out? Are they really $500/each :eek:
Any thoughts?

Most common issue is from knocking noises.

Other than that, if the leveling is still working but the car feels like it bounces easily.
BUT isn't hard

If the dampers are shot, they will usually leak. I haven't heard of them losing damping, but it is certainly possible.

If they aren't damping; bottoming out and bouncy, it is possible that they are worn out. It is also possible that (since your system isn't working properly) they have air in them, which doesn't damp at all, would be pretty much like a car without shocks. Any air in the shock will cause a loss of damping, and could even give you a thump when the air is out of the chamber and the first of the fluid hits the valve. It is possible if you had a sphere/accumulator failure that the pressurized nitrogen from the failed accumulator(s) has made its way into the damper or dampers.

Also, the system does rely on some pressurization (via the leveling pump and valve) to keep the fluid in the dampers from boiling/cavitation, if your system isn't working then the damping (especially jounce) can suffer.

There may be rebuild kits available for those shocks...

It's usually not the "shocks" (which aren't--they're levelers) but instead the accumulators (which are the shocks).

The accumulators are round pressure vessels hidden under the rear floor. They're more like $100.

Since the levelers are indeed VERY expensive, they are only replaced when leaking/broken and not necessarily in pairs.

If you look at "shock absorbers" as the component that dampens movement of the suspension, these are shock absorbers. True that there is a remote-mounted accumulator, much like on racing shock absorbers, and also true that they are used to carry some of the load thus keeping the car level, but their primary function is to damp motion in the suspension. The most accurate description in American English would be "shock absorber". I prefer "damper" as the Brits might say, but to me it is more accurate and has that delicious English flavor to it.

The shocks leaking is a sign that they are through.
The spheres also leak These are the general cause for a "Bouncy" rear .
The spheres are much cheaper than the shocks and changing them is a DIY job.

There's a flow chart for testing the spheres somewhere - do a search.

There's a ball joint at the bottom of the SLS shock where it attaches to the control arm... they wear out on high mileage cars and give a harsh ride and knocking sound (and feel) over bumps (assuming the accumulators and the rest of the system is OK). That's what is currently the situation on my 560SEL. Will have to replace both $L$ $hock$ to repair it on my car.

I believe that the 124T SLS mouting is different; conventional shock-mount at the top and two bolts fastening the lower which has a slight variation on the eye-bushing arrangement.

there's a balljoint at the bottom of a 124T SLS hydraulic ram (shock). i haven't seen a bad one but someone asked me the other day if i has spares because they had one with a bad balljoint so i guess it happens.

I have a 300te and I recently re-built the accumulators and replaced one of the leaky rear shocks. Before the car was bouncing like a pogo stick. Now it rides and handles like a new Mercedes. You can buy the shocks new for $382 online