Engine Overheating

How hot is too hot ?

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.

Causes Of Engine Overheating

1) A defective thermostat

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. 

2) A defective electric cooling fan or fan clutch

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.

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.

3) A collapsed radiator hose

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.

4) An eroded or loose water pump impeller

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.

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.

A gas is much less efficient in cooling your engine than a liquid 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

6) Fan belts fail

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.

7) Damaged Fan Shroud

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.

8) Dirty engine

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.  

10) Head gasket

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. 

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.

11) FRICTION Too much friction , oil and some additives aid to reduce friction.

Team Work sec B.N 1) Magdy Saaid Mohammed Ali. 4 14 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