I have a 1991 350SD with some kind of a vaccum control mechanism that is leaking oil (possibly blow by) all over the side of the engine compartment. This part is a 1 and 1/2" high by inch diameter cylinder, no visable part number, located on the driver side near a large blue round contol. On top of the cylinder is a two wire connector (part# 0115457128). Also on top is a clear vacuum line. At the bottom front is another clear with red stip vaccum line. At the very bottom is what looks to be another vaccum connection about 1" long but it starts out small then it enlarges to a about a 1/2 inch diameter. There is nothing connected to it, it's just open. This is where the oil or blow by is comming from. What does this part do and should oil be leaking out?