Hi,
There is an un-threaded hole at the bottom of the oil filter housing, and I cannot remember what goes into it. There are four bolts(2 long on top, and two short on the bottom) holding the housing to the block, the oil pressure sensor which screws into a threaded hole, and then there is the mystery hole which is located between the two short bolts on bottom. The shop manual just shows a line going from the bottom left bolt which spits in two. One of the branches passes through a bracket on its way to screwing into the block, while the other goes into the mystery hole. This is very frustrating since last time I checked a bolt can only go into one hole. I know there are different variations of this housing for different configurations of the OM606, but all of the other diagrams in the manual also show this mystery hole, with this same "one bolt, two holes" graphic as a solution.
Please help.

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'95 S350 REBUILT BEFORE THE RODS BENT!