Cooling System Maintenance and Repair

An engine that is overheating will quickly self destruct, so proper maintenance of the cooling system is very important to the life of the engine and the trouble free operation of the cooling system in general.

The most important maintenance item is to flush and refill the coolant periodically.  The reason for this important service is that anti-freeze has a number of additives that are designed to prevent corrosion in the cooling system.  This corrosion tends to accelerate when several different types of metal interact with each other.  The corrosion causes scale that eventually builds up and begins to clog the thin flat tubes in the radiator and heater core. causing the engine to eventually overheat.  The anti-corrosion chemicals in the antifreeze prevents this, but they have a limited life span.

Newer antifreeze formulations will last for 5 years or 150,000 miles before requiring replacement.  These antifreezes are usually red in color and are referred to as "Extended Life" or "Long Life" antifreeze.  GM has been using this type of coolant in all their vehicles since 1996.  The GM product is called "Dex-Cool".

Most antifreeze used in vehicles however, is green in color and should be replaced every two years or 30,000 miles, which ever comes first.  You can convert to the new long life coolant, but only if you completely flush out all of the old antifreeze.  If any green coolant is allowed to mix with the red coolant, you must revert to the shorter replacement cycle.

Look for a shop that can reverse-flush the cooling system.  This requires special equipment and the removal of the thermostat in order to do the job properly.  This type of flush is especially important if the old coolant looks brown or has scale or debris floating around in it.

If you remove the thermostat for a reverse flush, always replace it with a new thermostat of the proper temperature.  It is cheap insurance.

The National Automotive Radiator Service Association (NARSA) recommends that motorists have a seven-point preventative cooling system maintenance check at least once every two years. The seven-point program is designed to identify any areas that need attention. It consists of:

• a visual inspection of all cooling system components, including belts and hoses
• a radiator pressure cap test to check for the recommended system pressure level
• a thermostat check for proper opening and closing
• a 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
• an internal leak test to check for combustion gas leakage into the cooling system
• an engine fan test for proper operation
• a system power flush and refill with car manufacturer's recommended concentration of coolant