Let me know if you have a different theory or testing method that will prove of disproove my theory.

Question: Does excessive vacuum in the crankcase reduce oil pressure.

Research or supporting argument:
1. Oil pump creates a low pressure area(suction) in the pickup tube as the engine spins causing oil to be pushed up the tube by because the pressure in the crankcase is higher than the pressure in the tube(sucking the oil out of the pan)
2. The crankcase pressure will apply even forces(within reason) to all areas of the crankcase.
3. the oil pressure sensor or switch including our test equipment is a relative pressure comparing ambient air pressure to the oil pressure in the oil galley.
4. Other characteristics of the engine, variances and environmental conditions will make exact comparisons difficult.

Hypothesis: Oil pressure inside an engine remains the same under vacuum conditions even if the gauge reading indicate low oil pressure.

Experiment: measure oil pressure on fully warmed up engine at idle and compare results to same engine with lower than atmospheric pressure condition (Vacuum) applied to the crankcase. Easy for us since the fault on this engine is reducing the crankcase pressure below atmospheric pressure(vacuum in the crankcase) We will compare the oil pressure to the pressure in the crankcase and see if the change in oil pressure is the same as the change in crankcase pressure.

Results: The pressure did change about the same as the pressure applied to the crankcase. Without a more controlled environment we cannot gain more accurate results(bonus footage at the end has the closest measurement between crankcase pressure and oil pressure)

My thoughts: auto manufacturers would have to have a crankcase pressure sensor installed and use an oil pressure sensor instead of the switch commonly used in order to accurately display oil pressure conditions to the operator. This is too expensive for the results since crankcase pressure is normally +/-1psi and only exceeds those value when a fault is present.

Next question: would high crankcase pressure increase oil pressure reading relative to atmosphere.

Another question: If a pump including its inlet and outlet was situated in a complete vacuum(absolute pressure 0psi) would the pump be able to pump? Without the ability to create a pressure differential how can it draw fluid into itself. If this is true can we have an efficiency loss in the vehicle tested with vacuum in the crankcase because the pump may be creating a lower pressure differential?