I have not flushed my coolant since about 2006 (have paper bag on my head and hanging head in shame). So I am WAY overdue and this method sounds like a simple DIY. If I am interpreting it correctly, I basically need to:

1. Drain at radiator
2. Refill with citric or other flush material and water
3. Drain
4. Repeat 2 & 3
5. Refill with MB coolant

Correct?

# # #

I have clear coolant with some gooey crud on the sides of the expansion tank. I also just cleaned sticky brown residue from the inside-top of the upper radiator hose -- after removing the hose to see why it had a shiny oily film on the outside-top (no other coolant hose does).

The latter is of concern since it is oil and suggests a head gasket leak. I noticed the hose about a year ago and it has not increased. I just wipe it down between oil changes. Worst case: I have a slow leak into the coolant from the front of the engine, at the timing cover. (Everything behind that is dry as dust.)

Also, I once overfilled my coolant and used my topsider to suck some out. It is possible there was back flow of oil into the expansion tank since the amount of oil is small. A similar thing happened when I used the same topsider to siphon excess water from an outdoor aquatic plant container. A very small about of back-flow oil created a sludge that coated the sides of 3-gal container and took an eternity to remove. After the flush I should know what is actually occurring.

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2008 E350 4matic / Black/Anthracite

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Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black