Ford Explorer, Maintaince And Repair Manual, Page: 149 / 1119

contaminated or several years old.
At least once every 3 years or 36,000 miles (48,000 km), 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 too much water, it won't protect against freezing.
If you experience problems with your cooling system, such as overheating or boiling−over, check the simple
before expecting the complicated. Make sure the system can fully pressurize (are all the connections tight/is
the radiator cap on properly, is the cap seal intact?). Ideally, a pressure tester should be connected to the
radiator opening and the system should be pressurized and inspected for leaks. If no obvious problems are
found, use a hydrometer antifreeze/coolant tester (available at most automotive supply stores) to check the
condition and concentration of the antifreeze in your cooling system. Excessively old coolant or the wrong
proportions of water and coolant will hurt the coolant's boiling and freezing points.
Check 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 and the engine will overheat. Worn caps should be replaced with new
ones.
Be sure the rubber gasket on the radiator cap has a tight seal
Clean Radiator of Debris
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.
HOW TO USE THIS BOOK
INSPECTION 135