Final word: 300TD SLS vs. Spring support

[Delibes]

Okay, after much research on PeachParts and BenzWorld I cannot find an answer for the following question on a W123 300TD:

To what extent is the Self-Leveling Suspension an aid when loaded, and to what extent should it carry part of the empty weight of the wagon?

I heard the following arguments:

• The SLS is only an aid when the wagon is loaded. The springs should carry the weight and make the car look leveled when empty.
• The SLS and the springs share loads.
• The SLS carries part, if not most, of the empty weight of the wagon.

The reason why I am asking this is because I am about to rebuild my SLS valve in my sadding wagon and I do not want to overwork it by making the decision not to change the coil springs. Is there a final word on this?

[kerry]

There is a definitive answer to this question on this forum. I believe it includes a photo of the shop manual. The 'shocks', ie hydraulic rams hold XXXpsi even when the pump is not working. There is a thread with that number in it (660?) So yes, the hydraulic rams do carry a portion of the load under all circumstances if it is working correctly. This does not mean that the springs are not worn out but it does mean that if the car sags without any pressure in the SLS it is not necessarily an indication of any problem with the springs.

[Biodiesel300TD]

The rear springs and hydraulic struts work together all the time.
Here is an exerpt from the FSM about the SLS.
It comes from section 32-501, here is link to that - PDF of the SLS Info Section 32-501

Basically the strut is just an adjustable strut, ie the length is adjusted by an increase or decrease in pressure.
The springs are always "in theory" being compressed roughly the same whether the car is loaded or not.
That is due to the struts being adjusted with pressure
to raise and lower the car.

[69shovlhed]

if its sagging really bad, you might want to replace the springs anyway. 1 of my springs was broken. if you do plan on loading it up, you may want some heavier springs.

[Delibes]

Fantastic. Thanks to everyone! The topic is now closed.