Oil system myths

yellow rose said

I’m a bit stumped over the cavitation issue, because I’ve never seen it with a water pump or an oil pump.

I know I’ve heard that cavitation with a water pump is often caused because the suction side of the pump can’t keep up with the output of the pump.

I *think* I’ve seen cavitation on a belt driven fuel pump...but...I was never sure about that, and in the end I felt like the vent was too small but the experts say that it was cavitation and not the vent.

I didn’t have time to sort it out so I opened up the vent AND increased the hose diameter on the suction side of the pump, and it went away.

Which one fixed it? I have no idea.

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One of the biggest misconceptions when it comes to centrifugal pumps is that water or oil in a engine is “sucked” out of the oil pan or radiator. Which isn’t possible, what actually occurs is the is a pressure drop created by the impeller of a WP or in the case of a oil pump the rotation of the gears creates a lower pressure on the intake side of the pump which causes fluid to travel to a higher pressure. Atmospheric air pressure is 14.7 at sea level. It’s easier to understand it when you stick a straw in your glass of water or soda, when you “suck” on a straw, it travels up the straw because with your mouth you have lower the pressure on the suction side causing the fluid to travel up the straw. Unless your talking about positive displacement pumps which is a different animal.