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Engine Overheating Slide 2 How hot is too hot ? Slide 3 Slide 4 Most engines today are designed to operate within a "normal" temperature range of about 195 to 220 degrees F (91.28 to 105.28 degrees c). A relatively constant operating temperature is absolutely essential for proper emissions control, good fuel economy and performance. Engine overheating can be caused by a combination of two factors: too much heat or not enough cooling. Slide 5 Causes Of Engine Overheating Slide 6 1) A defective thermostat Slide 7 A defective thermostat The thermostat is a valve located in the cooling system of an engine, which is closed when the engine coolant is cold and opens gradually in response to the engine heating and thereby controlling the temperature of the coolant and rate of coolant flow through the engine block. Slide 8 Slide 9 2) A defective electric cooling fan or fan clutch Slide 10 A defective electric cooling fan or fan clutch The fan clutch is a coupling device that is located between the water pump shaft and the fan. The fan clutch is designed to improve the vehicle s cooling system efficiency while reducing the load on the engine and loss of energy caused by the fan itself. Slide 11 The Fan Clutch allows the fan to operate at lower speeds and effectively detach at higher speeds when the vehicle is moving and air movement due to velocity aids to cool the engine. Fan Clutch is wearing out or has failed to do its job then if the fan speed does not increase when engine is running hot or if the fan speed does not increase until engine is excessively hot. Slide 12 Slide 13 3) A collapsed radiator hose Slide 14 A collapsed radiator hose The radiator hoses should be in good shape, not cracked, brittle or leaking. Other than obvious damage, hoses can restrict coolant flow. Slide 15 Slide 16 4) An eroded or loose water pump impeller Slide 17 An eroded or loose water pump impeller A typical sign of a failing water pump is bad is typically a leak. A leak is typically occurring through the seal and bearing. Sometimes the water pump impeller can loosen up on the pump shaft and not turn, although the water pump pulley appears to be turning normally. If the impeller does not spin, there will be little or no circulation of coolant through the engine. Slide 18 Slide 19 5) A defective radiator cap The cooling system of an engine is designed as a sealed system with the engine coolant held under pressure. When under pressure, water and engine coolant boil at a higher temperature. As your coolant and water increase in temperature and approach the boiling point, the state of the liquid begins to change to a gas, seen as steam. Slide 20 A gas is much less efficient in cooling your engine than a liquid. So increasing the pressure increases the boiling point, allowing the coolant and water to do a much better job at removing heat. A functioning radiator cap will maintain its rated pressure. A 50/50 mixture of water and ethylene glycol will boil at 225 degrees in the cooling system Slide 21 6) Fan belts fail Slide 22 Fan belts fail Most cars on the road use a serpentine belt. A serpentine belt is a single belt that drives all the engine accessories. If a serpentine belt fails, all engine accessories will stop turning. That includes power steering, air conditioning compressor, alternator, and of course the water pump. Slide 23 Slide 24 7) Damaged Fan Shroud Slide 25 Damaged Fan Shroud The fan shroud directs the air from the fan, directly into the radiator making the fan efficient. A missing or damaged fan shroud will direct air from the fan directly through the radiator.. If there is not enough air is moving through the radiator to sufficiently cool the fluid, the result is an overheated engine. Slide 26 Slide 27 8) Dirty engine Slide 28 Dirty engine Dirt on an engine can act as an insulator, much like a blanket which keeps the temperature in the engine, rising its temperature. Slide 29 Slide 30 10) Head gasket Slide 31 Head gasket A head gasket is a gasket that sits between the engine block and cylinder head in an internal combustion engine. Its purpose is to seal the cylinders to ensure maximum compression and avoid leakage of coolant or engine oil into the cylinders. Slide 32 Overheating problems due to the head gasket may also be due to a break in the head gasket that is allowing combustion gasses to be pushed into the coolant, the result could be trapped air in the water pump. Slide 33 Slide 34 11) FRICTION Too much friction, oil and some additives aid to reduce friction. Slide 35 Team Work sec B.N 1) Magdy Saaid Mohammed Ali. 2) Mohammed Shehata Mohammed. 3) Mohammed Abd el aal Saad. 4) Mohammed Mansour Mostafa. 5) Mohammed Wafaey Mohammed Ali. 6) Haytham Atef El saied Ahmed. 4 14 4 29 5 1 5 14 5 20 6 25