The life and efficiency of your car's engine depend on, among other things, the quality of your radiator. The radiator takes the heat produced by the running engine and transfers it outside the car. An effective radiator should keep your car's engine cool at all times. If your vehicle has an automatic transmission, you need to check on the condition of the radiator at all times. Here are easy ways to tell when you need to replace the failing radiator with a new one.