Before proceeding to blame the thermostat, check the level of coolant, and the tension of the drivebelt. Disconnect the battery cable on four-cylinder models, drain the cooling system, loosen hose clamps, and remove hoses from the thermostat housing cover. Remove nuts from the thermostat cover then remove the old gasket and thermostat insert the new gasket and thermostat reattach the radiator hose refill the cooling system. Undo the hose clamp for 3.5L and 3.9 L V6 models and disconnect the hose at the fitting on the thermostat housing, pull off the housing cover, pull out the old stat in one piece with seal, insert new rubber seal inside housing cover with new stat, replace housing cover.