flushing power steering fluid

[diselsam]

I am thinking to flush the power steering fluid of a 2005 Mercedes C200 cdi.
After researching it seems there are 2 main ways to do it: by using a turkey baster/pump to suck out the fluid, or by disconnecting the return line.

Can you please help me telling me whether the correct place to disconnect is between the cooling pipe and the return hose from the coolant pipe?

I am thinking to disconnect this and to attach a hose to the cooling pipe on one end and to stick the other end in a bottle. Then I am thinking to block the return hose from the coolant pipe. With this setup up then without starting the engine and lifting the front of the car I am thinking to have someone turn the steering from lock to lock a couple of times and I will make sure to be adding fresh fluid. Then after purging 1 liter I am thinking to restore the piping, to check the level/add more fluid, turn the steering lock to lock without turning on the engine to remove any air. Finally I am thinking to start the engine and repeat the bleeding.

Do you think this will work?

 

[markjay]

I don't know the answers to your questions, but some years ago I did this on my Vauxhall Omega - syphoned out the old fluid from the reservoir using a large syringe, then filled if with new fluid, drove the car for a while, then re-did the process. It worked fine.

 

[diselsam]

Thank you Mark, that is fine. Do you know what difference the running/non running of the engine will make to the steering fluid flow? I hope my question is clear.

 

[MancMike]

The power steering pump is driven by the engine, so you'd have to have that on if you wanted to swap out all the fluid in the lines, pump and rack too. It's not advisable to go lock to lock without powered assistance.

I've always done it by replacing the fluid in the reservoir, going lock to lock a few times, replacing again, etc. Done that way, it's mathematically impossible to ever replace all the fluid, but you'll quickly get the vast majority of it changed.

 

[diselsam]

Thank you i-Conica. It seems that for all practical reasons it makes more sense to suck out/replace the fluid and do system bleed as per the book. The reservoir has a capacity of 250 ml. That means that with 1 liter I can do 4 purges. I have 1 more liter which will stay in the system. Your comment and that of Mark (thank you again!) makes me feel confident it is better like this and not risk air entering/stressing the system unnecessary. I will re-place the fluid after 5 years time. Thank you.