Changing W124 power steering fluid
 

Can anyone share their experience getting this job done? How much fluid does the system hold, and would siphoning out & replacing the fluid in the reservoir be worth doing? Can you siphon fluid out with the car running, and could any damage be done running the system dry for a short while?

Any/all input is appreciated:)

The reservoir holds about a quart of fluid, but the rest of the system (steering box and hoses) hold nearly another quart. Or at least that is true on the 108.

You can suck the reservoir dry, top up, run the engine and repeat the process until all clear fluid is present. But that takes a lot of fluid. Some people just suck out the fluid from the reservoir and top up, at least that is a partial change.

You could drain the resevoir, top up and the crack open the bleeder valve on the side of the steering box, attach a line to the valve and place the end in an empty milk jug. Next step takes like five hands, hold the line in the jug, start the engine and keep the reservoir topped until clear fluid enters the jug. Secure the bleeder and close the system.

When you have the reservoir dry, that is a good time to replace the steering filter at the bottom of the reservoir.

Thanks guys. I'll check out the bleeder valve-is there definitely one on a W124?

Understood on the filter-just picked up 3 of them. Changed the Diesel filter today, as I have an incomplete service history on that car and figured that would be a good first step. Next I'll flush it and replace the filter again-should be good for a long time after that.

I cannot say for sure if the 124 has one, but I can't think why it wouldn't. It would be toward the top of the box, probably on the inboard side. Looks just like a brake bleeder, maybe larger.

Plus. if this is on the 500, it will be a tight fit to see or access the bleeder. I'd check the TE first ;).

Mike T-

I'll do the "D" first-even more room underhood than the TE with M103 motor. I will check all my cars this afternoon and advise.

Michael,

What's the verdict - bleeder screw or not? Inquiring minds want to know :D.

Well, I never saw a bleeder...but I didn't look real hard either. What I did do was to siphon the reservoir dry, including the tube going to the steering box, and refilled it with new juice (I'd removed the filter for this). Fired the car up, let it run for a minute, then went thru the process again maybe 6-7 times. Used up 2 quarts of fluid, and think the job called for closer to 3 since the fluid still has a slight red tinge to it (replacement fluid's yellow). Big improvement, though-now you can read the writing on the filter through the fluid.

I'm gonna pick up a bunch of fluid and do all the cars-it looks like this system works pretty hard.

Thanks Senior Tangas:)

This may sound like a questionable practice but the way I have done this on W123 Diesels is to siphon out the reservoir, change the filter, then take the return line off the reservoir and direct it to an old coffee can that fits in the area, then have someone like my wife or one of my kids start the car while I carefully pour new fluid in, maintaining a little fluid over the filter, until the stuff coming out is clean. Then I shut the car off and put the line back and fill the reservoir, run the car, check it and top it off if it needs it. Job done.

My 190E 2.3-16 has too much stuff in under the hood to do that and I have therefore had the dealer change the fluid and filter. I think they do something similar, probably on a lift, and disconnect at the power steering box. If you have a lift or can get under the car to work on it comfortably, this is probably the easiest way to do it without using too much fluid, and it really allows you to flush the crud out. Jim

As I understand from the dealer, my method of siphoning the reservoir dry then re-filling it is the one used the dealer techs.

I just picked up 5 quarts to do my other 2 cars-the TE fluid looks terrible!