MotoBuddha wrote on 01/05/11 at 15:18:52:How do they get an accurate pressure reading when oil doesn't particularly "need" to go down that little dead passage to the gauge? I don't doubt that it works, I just don't understand exactly how. So there's pressure pumping through the system and oil will go wherever it can. Is it that even when the oil can't go anywhere, pressure is the same everywhere? Is it that the pressure isn't just in the direction of flow, but in every direction?
There does not have to be oil flowing directly by the sensor for there to be a readable, static pressure. So a pressure guage would work when threaded into either the front or bottom plug. Pressure would be the same throughout the oil lines only if they were 100% blocked at their outlets. In normal use, there is a dynamic pressure loss in every inch of line and around every bend. Pressure is greatest just after the pump and decreases the further you get from it.
MotoBuddha wrote on 01/05/11 at 15:18:52:Now for part two of my brain fart. If there's an oil cooler connected between the two highlighted ports, it seems to my tiny brain that only part of the oil would flow through the cooler while the rest flowed through the crossover. If that's the case, then at what point does the resistance in the oil cooler and lines have the oil thinking, "Screw this, I'm taking the shortcut," leaving very little willing to make the schlep through the cooler, leaving it full but rather stagnant? Or does the thermal change encourage flow through the cooler?
The oil would not say "screw this" and flip like a switch from one path to the other. The amount going through the cooler and cross pipe would adjust so that the pressure loss is the same for either path. The thermal change, if anything, would increase the viscosity of the oil returning from the cooler and decrease the flow through it. But the pressure drop across the two paths would still be the same.