I realize this thread is a bit old but I am hoping that I can get an answer about the egr. I just bought a 1990 300sel from a "mechanic" and there seems to be all kinds of top notch fixes on the mercedes. I realized that the EGR is not hooked up to anything and the car has a rough idle, serious vibrations, and bad economy. From all the research that I was able to find, this sounds like the EGR. I cannot seem to find a diagram that shows exactly it is supposed to be wired. All the diagrams that I have seen are for different motors and I cant seem to locate a missing vacuum connection. I would appreciate any help i can get on this. You posted a few pictures of the Y27 part but everything seems to be wired right on it. I just need to figure out where the hose goes to.