Radiator Repair Radiator pressure cap test to check for the recommended system pressure level. Thermostat check for proper opening and closing. Pressure test to identify any external leaks to the cooling system parts; including the radiator, water pump, engine coolant passages, radiator and heater hoses and heater core. Internal leak test to check for combustion gas leakage into the cooling system. Visual inspection of all cooling system components, including belts and hoses. System power flush and refill with car manufacturer's recommended concentration of coolant. Engine fan test for proper operation. By performing regular checks, NARSA radiator and cooling system specialists can help motorists prevent problems, emergency repairs and/or replacements, effectively saving the consumer time, trouble and money.