This morning did maintenance stuff on the 85 sd. Changed the tranny oil and filter, adjusted the valves, cleaned the banjo bolt at the back of the manifold, and replaced the broken air cleaner bracket. Anyway, while doing this I noticed that towards the back of the manifold there is a part that looks like a temperature, or pressure sending unit that is weeping what looks to be a mix of fuel and oil. Is this a pressure sensing switch of some sort for the tubo, and what exactly does it do? It looks like it needs replacing because it is leaking quite a bit.