Engine Cooling System
The function of the engine's cooling system is to remove excess heat from the engine, to keep the engine operating at the most efficient temperature, and to allow the engine to reach its ideal operation temperature in the shortest time possible. As petrol is burned in the engine, about one-third of the energy in the fuel is converted into power. Another third goes out the exhaust pipe unused, and the remaining third becomes heat energy. A cooling system of some kind is necessary in any internal combustion engine. If no cooling system were provided, parts would melt from the heat of the burning petrol, and the pistons would expand so much they could not move in the cylinders (called "seize").
The cooling system of a water-cooled engine consists of:
• the engine's water jacket
• water pump
• radiator and radiator cap
• cooling fan (electric or belt-driven)
• heater core
• expansion (overflow) tank
The cooling system removes around 1/3 of all the heat that is produced in the engine combustion chamber. The exhaust system also takes away much of the heat, but parts of the engine, such as the cylinder walls, pistons, and cylinder head, absorb large amounts of the heat. If a part of the engine gets too hot, the oil film will burn away and thus fail to protect it. This lack of lubrication can quickly destroy a car engine.
On the other side, if an engine runs at too low a temperature, it loses efficiency, the oil starts to get dirty (adding wear and reducing power output), deposits form, and fuel mileage is poor-- not to mention poor exhaust emissions. For these reasons, the cooling system only comes into action when the engine has heated up to its optimal temperature.
Common Engine Cooling Problems:
• Broken tubing. Hoses and tubing wear out and leak coolant fluid. Once the coolant has left the system it can no longer cool the engine and therefore the engine will over heat.
• Broken fan belt. The water pump is driven by the engine through a fan belt. If this belt breaks the water pump cannot turn and coolant will not be pushed through the car engine. This will also lead to the engine overheating.
• Damaged radiator cap. The radiator cap is designed to hold a certain pressure in the coolant system. If your cap does not hold enough pressure, then the car engine could overheat on hot days since the system never becomes pressurised.
• Water pump failure. Most commonly you will hear a horrible screeching noise and will be able to see engine coolant leaking from the front of the pump or underneath the car. Often there are early signs of trouble with small spots of coolant under the car after being parked overnight and a strong coolant odor whilst you are driving.
• Head gasket. Head Gaskets are a component that sits between and seals the main engine block to the cylinder head in your vehicle. This seal is critical and maintains a consistent operating pressure in the engine. On occasions a head gasket may fail to maintain this pressure and as a result will leak. In an extreme instance the gasket may actually crack, break or blow. The aforementioned damage will result in decreased engine pressure and a loss of power. Exhaust fumes could leak to the coolant system, causing an increased rate of engine wear and overheating. If leaks continue to occur before the repair takes place, the exhaust may start to steam and your catalytic converter may be damaged. Do you have large amounts of white smoke flowing out of your exhaust? Then you could have a problem with your head gasket.