To the left side of where your feet are in the car, there is probably a rubber bulb which you pump with your left foot. It pressurizes the washer fluid, and also activates the wipers. Many of them are broken and don't work any more. Mine was replaced with an electric pump which just has a switch added to the center console.
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!