NANO

ENGINE 273 MPFI 167 ENGINE SYSTEM COMPONENTS Radiator The radiator pipes and fins are aluminum , the tanks are plastic. A radiator is a type of heat exchanger. It is designed to transfer heat from the hot coolant that flows through it to the air blown through it by the fan. The coolant flows from the inlet to the outlet through many tubes mounted in a parallel arrangement. The fins conduct the heat from the tubes and transfer it to the air flow- ing through the radiator. Radiator (Pressure) Cap The radiator cap actually increases the boiling point of coolant. The boiling point of water increases when the water is placed under pressure. When the fluid in the cooling system heats up, it ex- pands causing the pressure to build up. The cap is only place where this pressure can escape, so the setting of the spring on the cap determines the maxi- mum pressure in the cooling system. The pressure pushes the valve open, allowing coolant to escape from the cooling system. This coolant flows through the overflow tube into the bottom of the overflow tank. This arrangement keeps air out of the system. When the radiator cools back down, a vaccum is created in the cooling system that pulls open another spring loaded valve, sucking water back in from the bottom of the overflow to replace the water that was expired. Cooling Fan The single-speed cooling fan is provided which increases the heat dissipation capacity of the radiator. Coolant Reservoir Tank (Auxiliary Tank) and Radiator Over Flow Tube In addition to supplying the circuit, the coolant reservoir absorbs the variations in the volume of the coolant as the temperature of the engine varies. The cooling system make use of a plastic container, which is connected to the overflow tube from the radiator. This container provides extra storage space for the coolant when it expands and is called the expansion, or overflow tank. Water Pump This is a centrifugal pump secured to the engine crank- case and driven directly by the balancer shaft. The pump circulates the coolant whenever the engine is running. The coolant leaving the pump flows first through the engine block and cylinder head then into the radiator and finally back to the pump. Coolant Temperature Sensor (For details Refer EMS Section ) Thermostat Location : Thermostat ismounted on cylinder head and positioned between coolant temperature sensor and timing cover. Working principle of thermostat : • For cool engine (immediately after starting): Thermostat does not allow water to flow to radiator (thermostat valve in closed position) instead water flows to thermostat by-pass outlet to water pump. Thus short circuiting of the radiator which helps for attaining engine working temperature in very short period. • As soon as the cooling water temperature reaches opening temperature of thermostat (i.e. 82 0 C), the thermostat valve start opening gradually and water flow start to radiator. At the same time thermostat by pass start closing gradually. • As the engine working temperature reaches thermostat full open temperature ( i.e. 92 0 C), thermostat valve opens fully and thermostat by- pass valve closes completely. Under such condition maximum quantity of engine cooling water flows to radiator. Satisfactory operation of thermostat is very much essential for efficient engine operation and longer engine life.