Take steps to avoid developing a clogged radiator . The inside of a radiator can become clogged with a buildup of sediment and deposits if the radiator isn't flushed and serviced regularly. This type of buildup impedes the free flow of coolant through the system and reduces cooling efficiency. Back-flushing your radiator and changing your coolant annually will reduce the likelihood that this condition will arise. Check the condition of your coolant .
New antifreeze has a bright yellow-green appearance with a distinctive iridescent sheen.
Older antifreeze that has begun to darken has likely lost some of its effectiveness. It's easy to test your antifreeze with a hydrometer. Simply squeeze the bulb and draw a sample of antifreeze up into the clear-plastic test compartment of the gauge. Pressure-test your radiator cap . Your vehicle's cooling system is a pressurized system.