One problem related to engine cooling system has been reported for the 2002 Ford Ranger. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2002 Ford Ranger based on all problems reported for the 2002 Ranger.
A plastic water heater control valve in the vehicle cooling system denatured and crumbled, leaking coolant out of the vehicle which could have caused an engine seizure had I not been aware of the situation. This is the second plastic part failure (first was the thermostat/temp sensor housing) which failed and leaked coolant during the warranty interval. Cooling systems are no place for plastic parts.