Having owned my e300d for the last 10 years I've become quite good at replacing the leaky fuel lines...but this is a new one for me. After smelling diesel and seeing puddles I checked all the fuel lines and they were good. I then took off the crossover pipe and the engine cover and see that all 6 of the "holes" are full of diesel as seen in the pic, so clearly there is a large leak in one or all of them.
What might this indicate? Return hose leak?