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Question about cooling system flow


April 20, 2004
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City, State
Cincinnati, OH
Year, Model & Trim Level
1996 XLT
I have a quick question about the flow of the cooling system in 2nd generation 4.0 Xs. I'm backflushing my engine and installing a new radiator, hoses, clamps, and thermostat. I know that the water pump pumps the coolant through the engine, then past the thermostat (if open), then into the top of the radiator, and then down through and back through the lower radiator hose into the pump again. But from where does the coolant that goes to the heater core come from? I would think that the coolant would flow through the hose coming from the intake manifold, through the core, and back to the water pump, but I have seen other places that it is the other way around. Also, if anyone can tell me which hoses coming from the four hose heater control (bypass) valve are the inlet for the heater core and which is the outlet, that would be helpful as well.

The heater gets its supply from the nipple on the top of the intake manifold near the thermostat. It is returned to a similar nipple on the water pump.