6.9 Hydraulic Oil Change

[WGB]

The old battery in my 450 (From my wife's previous 163 ML - 6 1/2 years old) finally died and refused to take a charge this weekend so I decided my 6.9 needed a new Mercedes Battery with original stickers etc and it's present perfectly good one transferred to the 450.

I came home after a half an hour of bartering with a new battery and all the oil necessary for a change of power steering fluid and also the hydraulic suspension.

I already have the filters for both systems and will use a suction oil changer to empty the reservoirs with the suspension on it's bump stops and then remove the reservoir and clean it out.

Does anyone have any other tips to clear as much of the old oil as possible out of the system?

My car has bleed valves but there seems to be no proscribed means to change the hydraulic oil.

Bill

 

[s class]

I replied over at M100.cc, but I can cut-and-paste here :

Bill, if you have the struts compressed as you propose, there will be little remaining fluid in the struts, valves and lines. Depressurise the 5th sphere into the tank.

If you have the struts compressed, but still supporting the weight of the car, I'm not sure, but I would think the 4 corner spheres would still be pressurised, and hence containing fluid - perhaps half a litre each? I suspect you plan to lift the car on the hoist, or will you be doing this with the car flat on the ground?

I think I would proceed as follows :

Lift the car
Discharge the 5th sphere
release the bleeder valves
compress each strut and support them in the compressed position, so that you can compress all 4 simultaneously

That should ensure the system is as completely empty as you can get.
Close the bleeders, lower the car, fill the oil and start the motor.

When you remove the tank, I find it is easier to leave the distribution valve connected to the three lines that enter it, and just unbolt the distribution valve off the regulator. Then disconnect the incomming pressure line to the regulator, and the one (think its one) remaining steel line at the rear of the regulator. The regulator can be removed from the tank by loosening the two 8mm nuts. Remove the tank, clean it out and marvel at the rubbish in the bottom. While you have the regulator out, remove the little gold coloured metallic filter and clean it out with kerosene and compressed air. I posted photos of this process over at W116.org.
The little metallic filter is NLA, so you have to reuse yours. When you see it out though, you will appreciate that proper cleaning is more than satisfactory. Replace the paper canister filter under the regulator. WHile the tank is out, replace the low pressure rubber lines from the bottom of the tank to the cooler, and then the one from the cooler to the pump inlet. Be warned, getting the one onto the pump inlet can be a bugger of a job due to poor access.