by Doris Donnerman
(last updated April 27, 2011)
If the needle on your temperature gauge moves to "hot," or the coolant warning light flashes on while you are driving, your car engine is overheating. Stop the car as soon as possible and let the engine cool down for at least fifteen minutes. You can tell if the engine has cooled sufficiently because you will be able to comfortably touch the radiator.
It is important that you don't try to remove the radiator cap while the engine is hot. The contents of your cooling system (chiefly, your radiator) are under pressure. This means that when you remove the cap, the hot liquid inside—mostly water and coolant—can boil over or you could allow steam to escape. Either way, you could be badly scalded by the hot liquid or vapors.
When the engine cools down, check the level of coolant water. This can be seen easily in most cars that have a plastic expansion tank, normally to the side of the radiator. If your car does not have an expansion tank, cover your hand with a thick cloth or glove and slowly unscrew the cap on top of the radiator. You can often simply top off the water level in the cooling system by filling the expansion tank to the level marked on it, or the radiator to just below the cap. Do not use cold water to refill an overheated engine—it could damage the engine.
The water level could have dropped because there is a leak in the radiator or coolant hose. While the engine is cooling down, you may want to check for these. A coolant hose can be repaired temporarily with tape, and a leaking radiator can be sealed temporarily with chewing gum.
Check the drive belts. Some cars have a generator drive belt that also drives the water pump and radiator fan. If this breaks or slips the engine will overheat.
If everything looks in order, your car may be overheating because a sensor, gauge, or thermostat is faulty in your engine. A quick trip to an auto repair shop should be able to identify and solve any of these problems.
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