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

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

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.