oil pressure question

[air-cooled or diesel]

in a gas engine, you have vacuum @intake, and at a loss of power. diesels have pos pressure, so they have to make vac outside, obviously at a loss. its@intake, &due to valve overlap, so the engine breathes.

[82vdub]

If you look at any old GM diesel pickup or the old 80's-90's Olds diesels, it's typically got a hydraulically assisted brake booster. It's easy to tell as there isn't the large diaphragm behind the master cylinder, and there's hard piped hoses going to it. All diesels will need an engine driven, hydrauically driven, or electrical vacuum pump on them.

Oil PSI's rise with engine RPM - that is unless you are sucking air or a foamy oil mix into the oil pump.

[air-cooled or diesel]

in some motors i had heard of part of the theory to oil pressure, as rpms go up pressure goes up, when you let off the revs the oil pressure drops, sometimes to less than idle, which isnt a problem as long as it doesnt go too low.

[Fatmobile]

The vacuum pump on these also drives the oil pump.
You have oil pressure so you probably have a vacuum pump. Exception would be the early non-power brake VW diesels.
Because there wasn't a hose from the vacuum pump to that port on the front of the block, you probably have the vane-style pump, the right one in the picture Tyler provided.