Checking The Radiator Cap
While you are checking the coolant level, check the radiator cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost in the form of steam and the engine will overheat. If necessary, replace the cap with a new one.
Clean Radiator Of Debris
At least once every two years, the engine cooling system should be inspected, flushed, and refilled with fresh coolant. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion. If the coolant has been diluted with too much water, it won't protect against freezing.
The radiator cap should be examined for signs of age or deterioration. Fan belts should be inspected and, if necessary, adjusted to the proper tension (please refer to "Belt Tension Adjustment" in this section).
Hose clamps should be tightened, and soft or cracked hoses replaced. Damp spots, or accumulations of rust or dye near hoses, the water pump or other areas, indicate possible leakage. This must be corrected before filling the system with fresh coolant.
Check the overflow tank cap for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat. A worn cap should be replaced with a new one. The coolant should be free of rust and oil. If oil is found in the coolant, there may be a major mechanical problem.
Periodically clean any debris (leaves, paper, insects, etc.) from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.
Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful; the fins are very soft! Don't wiggle the fins back and forth too much. Straighten them once and try not to move them again.