Power Steering Fluid Replacement

[TJMart]

My supply hose from the reservoir to the pump is leaking. My system was filled with ATF when the steering box was rebuilt a couple years ago. I have ordered new low pressure hose for the supply and return hoses and a new high pressure hose. I want to get rid of the ATF and fill the system with the proper MB Power Steering Oil.

What is the best way to empty the ATF out of the steering box and pump? Can I disconnect the return hose and use a container to catch the fluid with the engine running and turning the steering wheel back and forth or should I just use the bleed nipple to empty the system. I don't want to damage the pump or box so is there a better way? 

Thanks in advance.

Tony

[MikeSimon]

Tony, what do you think the advantage of MB steering fluid is over ATF? I worked for the company that made the W113 power steering pump. We specified ATF or DexronII for the P/S system. The only advantage of the MB fluid is, there is a star logo on the container and the dealer makes more money.

[TJMart]

Thanks for sharing your opinion but I researched this site and determined for my car I would use the Mercedes fluid. See link https://www.sl113.org/forums/index.php?topic=27816.0 and Tyler's posts in particular. Also the Technical manual mentions MB power steering fluid so that's what I prefer to use.

I ordered my parts from the Classic Center including the fluid and paid $9.55 per quart which is very reasonable.

My post was really about how to flush the system so hopefully others will share their expertise/opinions on that.

[MikeSimon]

I am not sure if the bleed nipple is a good way to flush the system. Start with disconnecting the return hose from the steering gear to the pump. Run the engine and turn the wheel as you say. While it is not a big deal to run the pump dry for a few seconds - you will see the reservoir being empty - you can fill the MB fluid into the reservoir before you reach that point. As cost doesn't seem to be an issue, wait until the different color fluid will come out of the return hose. This may prevent air from getting into the system and you don't have to bother with trying to bleed it. If the MB fluid is the same color as the ATF,...well, what I said before.

[WRe]

Hi,
what about flushing the power steering with compressed air? I found this procedure in a German MB forum.
...WRe

Removing old hydraulic fluid in the power steering can sometimes be a tedious job. Compressed air is quick and thorough.
The hydraulic fluid in the power steering should be changed occasionally. It is advisable to remove as much of the old dirt as possible, which is almost impossible without additional tools, especially in the case of the steering gear. Nevertheless, the system should be clean inside before refilling. That's why I first removed the old oil from the reservoir with a 500mL workshop syringe and then unscrewed the suction and pressure hose on the pump (put a drip tray or baking tray on your loved ones, some more oil will still run out).
Then I put a compressed air gun in the pressure hose. But don't press just yet, otherwise
A hose of the appropriate size is inserted into the suction line and the other end is placed in a clear plastic bottle. To relieve the pressure in the bottle when blowing through, we recommend a small hose like the one in the picture below (the white one). Wrap a workshop roll or a rag around the bottle opening and fix it with a cable tie.
Then you sensitively (!!) press the compressed air gun and gradually blow the whole old soup out of the steering with increasing pressure. Turn the steering from time to time between the compressed air blasts. When nothing else arrives in the bottle, the process is over and you can look at your used oil in it. If you like, you can then fill in a few 100ml of fresh oil with a small funnel on the pressure line and blow it out as well, so to speak as a flush.
Finally, clean everything up nicely, put in new oil and filter, bleed according to WHB, and the steering is ready for many kilometers again.
And a year and a half later, the power steering pump looks so clean from the inside (I opened it to change the inner seals).
That really speaks for the rinsing process described above,

[stickandrudderman]

A two-man job which is much easier on LHD than RHD.
Remove the reservoir lid. Attach a long hose to the bleed nipple, loosen the nipple and run the hose into a waste container. Run the engine and turn the steering lock to lock; this will discharge the fluid into the waste container. Meanwhile, have your helper add the new fluid to the reservoir until you are satisfied that the fluid is completely flushed with new.
Replace the filter in the reservoir when you're done.

[wwheeler]

Might also want to replace the filter in the P/S reservoir.

[TJMart]

A two-man job which is much easier on LHD than RHD.
Remove the reservoir lid. Attach a long hose to the bleed nipple, loosen the nipple and run the hose into a waste container. Run the engine and turn the steering lock to lock; this will discharge the fluid into the waste container. Meanwhile, have your helper add the new fluid to the reservoir until you are satisfied that the fluid is completely flushed with new.
Replace the filter in the reservoir when you're done.

Thanks Stick. I didn't want to take a chance and damage the pump so this will make sure of that by having fluid in the system at all times and the bleeding will be done at the same time. Yes I have removed my reservoir to clean, paint and replace all hoses, lid gasket and the filter. It was amazing how much sediment was at the bottom of the reservoir and on the metal plate that covers the filter. All will go back together when parts are received before I begin the flush.

Just as an FYI for everyone, the high pressure hose is NLA from Mercedes but K & K sells it. It looks just like the original but downside is that they get it from Germany so I should have it soon. Thanks to all for your posts!

Tony