Modern automobiles are equipped with a liquid cooling system designed to remove waste heat from the engine and disperse it into the atmosphere through the radiator. The radiator cap pressurizes the system to raise the boiling point of the coolant, and a thermostat controls the coolant flow through the radiator to maintain the engine at the proper operating temperature. Damaged cooling system components and low coolant level can cause the engine to overheat and lead to severe engine damage.
Engine Damage
Overheating can cause damage to the thermostat when the paraffin pellet over-expands and leaks from its container. This prevents the thermostat from reaching the full-open position when reaching operating temperature on subsequent trips, and can contribute to a persistent overheating condition. Engine oil loses viscosity, preventing it from properly lubricating the engine components, causing wear and excessive metal-to-metal contact between the engine components. Moving parts such as the valve train components and the pistons can increase in diameter from the heat, thus reducing clearances within the engine, leading to galling, scoring and the eventual seizure of the engine. Cylinder heads increase in size from the heat at a greater rate than the engine block, leading to relative motion between the cylinder head and the block that can cause failure of the head gasket, and in extreme cases, cracked cylinder heads. Avoid catastrophic engine damage by turning off the engine at the first sign of an overheating condition.
Overheating Causes
Automotive engines overheat from several causes. The most common is poor maintenance of the coolant, to include low coolant level and insufficient coolant maintenance. Over time, coolant loses its capacity to draw heat from the engine and disperse it through the radiator. Low coolant level also diminishes the cooling systems efficiency and causes a heat buildup. Improperly functioning thermostats act as a restriction in the cooling circuit and prevent sufficient flow through the radiator. Engine oil helps remove heat from the engine components, and low or worn-out oil can contribute to a buildup of waste heat in the engine. Radiators can suffer from sedimentation, causing the internal tubes to clog, which prevents the radiator from properly transferring heat. Make certain the radiator fan belt has proper tension, or if it is an electric cooling fan, check that it is activating once the engine reaches operating temperature.
Overheating Prevention
Proper maintenance of the cooling system and engine oil is essential to the prevention of overheating. Follow the vehicle manufacturer's recommended service intervals and procedures to maintain the cooling system and prevent overheating. Check the rubber gasket on the radiator cap and replace the cap if it is damaged or worn. Flush the radiator to help prevent sedimentation, and replace the coolant at proper intervals. Repair any hoses or gaskets at the first signs of leakage to prevent losing coolant. Change the oil at proper intervals to maintain its heat transfer and lubricating properties. Keep the exterior of the radiator clean and free of debris that could reduce airflow and inhibit heat transfer. Maintain proper coolant level within the radiator and the overflow reservoir.
Emergency Overheating Procedures
In an overheating situation, it is possible to remove modest amounts of excess heat from the cooling system by turning the passenger cab heater to the on position and turning the heater blower to high. This removes some heat from the system and vents it into the passenger compartment. Although the passenger compartment might become uncomfortably warm, this measure may hold off critical overheating for a few moments, giving you time to navigate to safe emergency parking. Pull over as soon as it is safe and turn off the engine. Open the hood and allow the engine time to cool through convection before attempting to remove the radiator cap. Cover the radiator cap with a rag before removing it to prevent injury from hot coolant or steam escaping from the radiator. Never add cold water or coolant to an overheated engine, or severe engine damage will occur.
Overheating Recovery
After the problem that caused your car to overheat has been addressed, flush and refill the cooling system if that wasnt done as part of the repair. Test the thermostat and radiator cap for proper operation and replace as needed. In addition, change the engine oil since the overheating condition can prematurely degrade the oil.
