Thermostat, Engine Cooling

The 3.7L / 4.7L / 5.7L engines use a pellet-type thermostat that controls the operating temperature of the engine by controlling the amount of coolant flow to the radiator. The 8.3L engine uses a movable sleeve type thermostat. On all engines the thermostat is closed below 195°F (90°C). Above this temperature, coolant is allowed to flow to the radiator. This provides quick engine warm up and overall temperature control.