I hate to disagree with Lance, but this is not entirely correct (its not entirely wrong either). A 4" sag is huge and indicates a leaking SLS and bad springs or a grossly overadjusted ride height.

I can only speak to the w123, but some of the info may translate to the w124.

When all is working correctly, the entire weight of the unloaded parked car should be supported by the springs. The SLS kicks in only when extra load is added, either through cargo or forces exerted while driving. So, unloaded and parked the SLS should be "resting", unloaded and driving the SLS is working to offset changes in "load" (bumps, turns etc.), and loaded (parked or driving) the SLS is working.

If is sags when parked there are at least 2 problems (maybe three). The first is that the SLS system is not holding pressure and is most likely leaking down past the o-rings in the valve (either internally or externally). I'm currently rebuilding the valve on one of my wagons and will post details when I'm done. The second possible problem is that the springs are no longer supporting the car at the correct height, and they should be replaced (or shimmed). The third possible problem is that the ride height is overadjusted, and the SLS is carrying the rear at a height beyond the capacity of the springs.

Its easy to differentiate between the last two problems. When you remove the valve for rebuilding, unload the car (i.e. empty out your tools/spare engine/four linebacker friends) and look at where the rear end sits. If it sags badly, replace the springs. If it sags a little, you might be able to get away with spring shims. If it looks "normal", readjust your SLS linkage.

"Normal" ride height is no passengers on level ground. You should be able to see the top of the rear tire when you look at it straight from the side (it should not be obscured by the fender). Now walk away from the car, does it look like its sitting level?

Of course, none of this actually addresses your questions about ride quality. That sounds like accumulators to me, assuming the SLS pump is working and you have no leaks.

Doh! I missed that this is an old thread revived.

The SLS on my 1987 300TDT is not auto-leveling like it should be. When the mechanic doing the inspection on the vehicle looked at it, he claimed that the SLS control valve was leaking and that would cause the SLS to not function properly. The ride height on my 300TDT seems to be correct, and the ride is not excessively bumpy.

I have a new SLS control valve I bought on E-bay a while back and I was plannning on swapping the valve out in order to fix the SLS. Based on the posts here I might swap out the accumulators at the same time. One other thing I noticed is that the rubber boots that cover the shocks/hydraulic actuators have rotted away. I checked the EPC and with Caliber Motors and apparently the boots aren't available separately (not that they can be replaced anyhow). New shocks cost $430 each, which is a lot money. Does anybody have any ideas on how to cover up the rods on the shocks with an aftermarket boot to prevent long term damage to the shock seals from dirt?

Thanks in advance.

-Steve

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1987 300TDT smoke silver w/ burgundy leather interior
2000 VW Passat wagon indigo blue w/ beige leather interior
1985 Mustang SVO
1970 Chevrolet K10 fleetside, shortbed

They are behind the rear seats under the floor.

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