I purchased my '96 Taco 4x4 with 2.7 4cyl new. It now has 270,000 miles on it. I've never noticed until now, but the lower hose remains much cooler (74? or so surface temp) than the top hose (174? surface temp). I've replaced temp guage sender - it reads normal, as the original did. I've replaced the thermostat - it too opens and closes as the one it replaced. Dealer tells me the cooling system is performing perfectly and there's no need for concern. Can anyone explain why the lower hose (which goes into the thermostat housing) is colder than the top hose by that much difference in temp range? The engine does not overheat, and the heater performs normally.