Overall coolant flows: Out of the bottom radiator tank, into the bottom of the engine through pumps, through the block and out the heads and upper hoses to the top tank, then back through. So which way does coolant flow through the heater hoses? Looking at the layout I could make an argument for either direction. Not willing to unhook a hose and start the engine just yet.
I believe it flows out of the head into the heater core. I have a shut off valve mounted in the head before the heater hose. The return hose must be the one that goes into the lower radiator hose.
X3, Both the radiator and the heater excange heat to the outside so it would be logical for any cooled water to reenter the system at the bottom of the radiator/engine combination. Frank
X3 The pump is causing suction on the lower hose and pressure in the block which causes the flow through the heater.. The water coming out of the head is hotter and that is what you want going into the heater. Not the water that has already been cooled by the radiator.
Yep, that is correct, and the heater doesn't do quite as good of a job as the radiator does cooling the water back down. When I am using the heat in my car my right side runs a few degrees hotter than the left side.
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