I have had an 83' 500sl (Euro) for a couple of months now. The car runs very well but seems to have many little things that need repair, probably not a lot considering that it is 17 years old. Anyway from outside of the car the fuel pump always buzzes, I would consider this sound to be normal from my experience of electric fuel pumps. Please correct me if I am wrong. From inside though there is what I would call a steady whine. It doesn't seem to increase or decrease in pitch, regardless of driving situation or idle. The noise is louder than I would expect but, I have no experience with these older cars, I had assumed that this also was the fuel pump. Although If I had to guess I would say the sound seems to originate from the rear drivers side of the car,(opposite of where the fuel pump is). Any thoughts or experiences would be appreciated.