Letting the pump go dry isn't a good thing, either. I think that it is fair to say that the average "first timer" is going to be shocked at the rate at which fluid is emptied from the pump reservoir if the procedure is done with the engine running. If you are going to do it that way, put all your flushing fluid in one container so you don't have to fumble with three individual quart bottles.

That's odd, the MB fluid I picked up was a green mineral oil (Pentosin 11S)

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95 E300 Diesel 200K

Isn't Pentosin 11S synthetic? Can hydraulic fluid be both mineral and synthertc?

Sixto
87 300D

If your assistant is quick on the switch the pump does not really go dry. There may not be a flooding of liquid, but there is PLENTY of fluid film in the pump to prevent any damage.

Folks, the method I described is the ACCEPTED method. It has been done in shops by pro's hundreds of thousands, probably MILLIONS of times. I personally would NOT post it here if there were ANY danger of damage.

I wouldn't drive the car without any fluid or with the hose removed.

I did the job last night and I just had the engine running when I turned the wheels lock to lock about a dozen times.

I sucked out the fluid with a turkey baster(new).

It took a while but the fluid is crystal clear now.

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1993 W124 300D
-297K on the clock as I type this.

They definitely have synthetic but I don't think mine had synthetic in it.

The MB fluid I got was an amber color and the fluid in the car was a really dark, cloudy amber.

This is on a '93 so I am assuming that they hadn't gone synthetic then.

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1993 W124 300D
-297K on the clock as I type this.

Sorry, I wasn't clear on this. It is synthetic, white mineral oil is one of the ingredients. I pulled out the can and it reads "Synthetic automotive hydraulic fluid." It is a blue can from Mercedes with Q 1 32 0001 on it and it says it is Pentosin CHF 11S.

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95 E300 Diesel 200K

You coud say the same for open heart surgery. It's an accepted procedure. Pro's have done it millions of times. And there is a very high probability that an amateur doing the procedure for the first time won't get it right.

I was working from a 1 gallon jug, had a funnel in the throat of the PS pump reservoir. Part of my problem was that the funnel blocked my view; I didn't realize the fluid was going through so quickly. Next time (later this Fall) I may try loosening the serpentine belt and turning the pulley by hand. I'll have the front wheels off the ground to make them easier to turn.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

After I slipped a new seal between the reservoir and pump I turned the pulley by hand until there were no more bubbles. I don't know if that's enough pressure to force clean fluid through the convoluted path. The low speed and pressure might allow more time for new and old fluid to mix. Can you set a buffing wheel on a drill against the pulley for a little more rpm?

Sixto
87 300D