Low oil pressure?

Jadaharabi said

If that plug is not in there and the engine is pumping oil then let's say for example the oil pressure gets up to 60 pounds. The bypass in the pump opens and drops the pressure in the pump so then by not having the plug in that line the oil goes back to the filter and it stops going up to the top of the motor then pressure drops bypass kicks out oil pressure builds up again feeds the top of the motor. Until pressure builds up bypass opens in the pump and once again the oil pressure drops.

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I think it's more like if the pressure bypass spring is set at 70 psi the plunger starts compressing the spring as the pressure goes up, when it gets high enough it bypasses and the pressure stays at that pressure, it doesn't go up and down. When the pump slows down enough to close the port then it just goes down in pressure. If the plug is not in the block the oil will flow straight up to the main galley and through the motor but not through the filter, with the passage plugged it goes through the filter then to the main galley. End of story.