Cooling System Description and Operation (1.7L Diesel LPL and
LPV)
Cooling System
The cooling system's function is to maintain an efficient engine
operating temperature during all engine speeds and operating
conditions. The cooling system is designed to remove approximately
one-third of the heat produced by the burning of the air-fuel
mixture. When the engine is cold, the coolant does not flow to the
radiator until the thermostat opens. This allows the engine to warm
quickly. Refer to the following illustration for the components in
the system and the basic flow path of the coolant.
The cooling system consists of the following components:
Water Pump
Water pump is a component of the engine cooling system and
circulated the coolant from each cooling circuit components. This
water pump consists of sealing, bearing, pulley (1) and housing (2)
and is driven by the drive belt to loose noise to water pump
pulley. Water pump apply drain hole cup to cap to prevent coolant
leakage for customers. Water pump is not open impeller type but
closed plastic impeller type (3) to increase the cooling
efficiency.
Thermostat
The thermostat is a regular part of the thermostat housing (1).
The thermostat controls coolant flowing. By coolant temperature,
the wax-pellet (2) of the thermostat expanded and shrunk
mechanically main spring to flow the coolant. The thermostat begins
to open at 88°C (190°F) and fully open at 103°C
(217°F).
Radiator
The radiator is a heat exchanger. It consists of a core and 2
tanks. The aluminum core is a tube and fin cross-flow design that
extends from the inlet tank to the outlet tank. Fins are placed
around the outside of the tubes to improve heat transfer to the
atmosphere. The inlet and outlet tanks are a molded, high
temperature, nylon reinforced plastic material. A high temperature
rubber gasket seals the tank flange edge to the aluminum core. The
tanks are clamped to the core with clinch tabs. The tabs are part
of the aluminum header at each end of the core. The radiator also
has a drain cock located in the bottom of the left hand tank. The
drain cock unit includes the drain cock and drain cock seal. The
radiator removes heat from the coolant passing through it. The fins
on the core transfer heat from the coolant passing through the
tubes. As air passes between the fins, it absorbs heat and cools
the coolant.
Surge Tank
The surge tank is a plastic tank with a threaded pressure cap.
The tank is mounted at a point higher than all other coolant
passages. The surge tank provides an air space in the cooling
system that allows the coolant to expand and contract. The surge
tank provides a coolant fill point and a central air bleed
location. During vehicle use, the coolant heats and expands. The
increased coolant volume flows into the surge tank. As the coolant
circulates, any air is allowed to bubble out. Coolant without air
bubbles absorbs heat much better than coolant with bubbles.
Cooling Fan
The cooling fan is mounted behind the radiator in the engine
compartment. The engine cooling fan is driven by electric power.
The cooling fan draws air through the radiator to improve the
transfer of heat from the coolant to the atmosphere. As the fan
blades spin, they increase the flow of air across the radiator core
and across the condenser on air condition (A/C) equipped vehicles.
This helps to speed cooling when the vehicle is at idle or moving
at low speeds.
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