That was pretty bad of me not to say how I got to it!! I think from the top which is why I made the comment about the engine being cool. I think I used a long extension on my ratchet. Sometimes universal joints work on these problems. I got a 3/8" impact type universal joint that works really well. I don't use it for impact, it just works better than the old kind of universal joint. It is black and has kind of a ball joint in it. Anyway it is possible and is well worth the effort to drain everything as good as you can. I had to flush the system to get all the old coolant out so using distilled water is basically out unless you have 20 gallons or so. Be sure to use the correct coolant which I think is the Zerex G-05 for your car. Or the Mercedes brand from the dealer. Same stuff, light yellow.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra