I believe you should be able to easily view the radiator drain from under the front of your car by opening the towing eyelet cover.

From your picture, there is green corrosion above the drain indicating the source of the leak. Do your self a favor and when you do drain the coolant, replace it with one that is safe/compatible with your radiator (Mercedes coolant or Zerex G-05 antifreeze/coolant type).

Follow the advice above and get your system pressure tested. If you do need a radiator, replace it. They are competitively priced from this site's parts department.

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)