500SEL mystery fluid reservoir...help!

[plink49]

Upon inspecting my relatively newly acquired '92 500SEL, I have discovered a fluid reservoir on the right-front engine compartment, under a small access panel. The white plastic reservoir is fairly large, unlike steering fluid ones. The cap is marked "Hydraulic Fluid". What concerns me is that the fluid that is in there is well below the minimum on the little dipstick in the cap. First, what is this reservoir/fluid for and second, exactly what type fluid do I top it off with? Please help.

 

[jaques2k]

Hi! I think you mean the hudraulic suspension reservoir, wich is for your rear self-leveling suspension. I myself has asked this once on this forum, so now I can shear of my wisdom! =) This is what "Talbir" wrote: The hydraulic oil is pumped to the rear struts, when car is under load at the rear. The struts then raise to support the springs. With self-levelling suspension the car wll not sag at the rear under load, as a car does do with normal shock absorbers.
You need to fill it with hudraulic fluid, probably some Mercedes original (maybe some other can answere that better - can you put in any similar hydraulic fluid?).

 

[andy_k]

first off you don't need to "fill it" there's a dipstick in the cap to tell you the required level.

The fluid is Mercedes Hydraulic Oil - ZHM spec oil and costs approx £8.50 a litre from the dealers.

HTH

Andy K

 

[jaques2k]

Sorry for that! =) Of course you don´t have to fill it if it´s not too little in the reservoir, but shouldn´t it be within the readings on the dipstick?? I don´t know, but "Plink" wrote that it was below the minimum on the dipstick...?

 

[talbir]

You MUST fill the reservoir to the required level indicated by the plastic level stick, which is approx 3/4 of the reservoir, with the car UNLOADED.

With load in the boor/rear, hydraulic fluid, fluid is pumped to the rear struts - hence fluid level is and should be low with car under load.

So ensure all load is removed when checking fluid level.

 

[plink49]

Thanks so much for the replies! I should have guessed that the required fluid would be a dealer-only item...at an inflated price. Ah, the love of MBs!