upon closer inspection, it appears that the oil might be coming from a different area. there is a what looks like an allen bolt and possibly a washer and gasket on the block right next to the alternator. it's very large. it is forward and down from the front of the exhaust manifold. what is this thing and what do i have to do to stop the oil from leaking?

thanks

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dew
86' 190e 2.3L 16v