[Rob. Smith]

YUP ! If you look at the pump and it turns clockwise...the top one is sucking and the bottom one is pressurized. When I ran my engine with the bottom fitting plumbed into a bucket it started to fill that bucket mighty fast. I didn't have enough time or water to see what happens when the thermostat opens. I reckon when the thermostat opens all the pumps pressure goes through the engine and out to the radiator..larger flow path.