Operation; General Description; Radiator; Surge Tank - Daewoo CIELO EURO III Manual

1D – 1 9 ENGINE COOLING

GENERAL DESCRIPTION

AND SYSTEM OPERATION
GENERAL DESCRIPTION
The cooling system maintains the engine temperature at
an efficient level during all engine operating conditions.
When the engine is cold, the cooling system cools the
engine slowly or not at all. This slow cooling of the en-
gine allows the engine to warm up quickly.
The cooling system includes a radiator and recovery
subsystem, cooling fans, a thermostat and housing, a
coolant pump, and a coolant pump drive belt. The timing
belt drives the coolant pump.
All components must function properly in order for the
cooling system to operate. The coolant pump draws the
coolant from the radiator. The coolant then circulates
through water jackets in the engine block, the intake
manifold, and the cylinder head. When the coolant
reaches the operating temperature of the thermostat,
the thermostat opens. The coolant then goes back to the
radiator where it cools.
This system directs some coolant through the hoses to
the heater core. This provides for heating and defrost-
ing. The surge tank is connected to the radiator to recov-
er the coolant displaced by expansion from the high
temperatures. The surge tank maintains the correct
coolant level.
The cooling system for this vehicle has no radiator cap
or filler neck. The coolant is added to the cooling system
through the surge tank.

RADIATOR

This vehicle has a lightweight tube-and-fin aluminum ra-
diator. Three models of radiators are available: small,
standard, and heavy duty. The three models vary only
by capacity. Plastic tanks are mounted on the right and
the left sides of the radiator core.
On vehicles equipped with automatic transaxles, the
transaxle fluid cooler lines run through the left radiator
tank. A radiator drain cock is on this radiator.
To drain the cooling system, open the drain cock.

SURGE TANK

The surge tank is a transparent plastic reservoir, similar
to the windshield washer reservoir.
The surge tank is connected to the radiator by a hose
and to the engine cooling system by another hose. As
the vehicle is driven, the engine coolant heats and ex-
pands. The portion of the engine coolant displaced by
this expansion flows from the radiator and the engine
into the surge tank. The air trapped in the radiator and
the engine is degassed into the surge tank.
When the engine stops, the engine coolant cools and
contracts. The displaced engine coolant is then drawn
back into the radiator and the engine. This keeps the ra-
diator filled with the coolant to the desired level at all
times and increases the cooling efficiency.
Maintain the coolant level between the MIN and the
MAX marks on the surge tank when the system is cold.

COOLANT PUMP

The belt-driven centrifugal coolant pump consists of an
impeller, a drive shaft, and a belt pulley. The coolant
pump is mounted on the front of the transverse-mounted
engine, and is driven by the timing belt.
The impeller is supported by a completely sealed bear-
ing.
The coolant pump is serviced as an assembly and,
therefore, cannot be disassembled.

THERMOSTAT

A wax pellet-type thermostat controls the flow of the en-
gine coolant through the engine cooling system. The
thermostat is mounted in the thermostat housing to the
front of the cylinder head.
The thermostat stops the flow of the engine coolant from
the engine to the radiator in order to provide faster
warm-up, and to regulate the coolant temperature. The
thermostat remains closed while the engine coolant is
cold, preventing circulation of the engine coolant
through the radiator. At this point, the engine coolant is
allowed to circulate only throughout the heater core to
warm it quickly and evenly.
As the engine warms, the thermostat opens. This allows
the engine coolant to flow through the radiator, where
the heat is dissipated through the radiator. This opening
and closing of the thermostat permits enough engine
coolant to enter the radiator to keep the engine within
proper engine temperature operating limits.
The wax pellet in the thermostat is hermetically sealed in
a metal case. The wax element of the thermostat ex-
pands when it is heated and contracts when it is cooled.
As the vehicle is driven and the engine warms, the en-
gine coolant temperature increases. When the engine
coolant reaches a specified temperature, the wax pellet
element in the thermostat expands and exerts pressure
against the metal case, forcing the valve open. This al-
lows the engine coolant to flow through the engine cool-
ing system and cool the engine.
As the wax pellet cools, the contraction allows a spring
to close the valve.
The thermostat begins to open at 87 C (189 F) and is
fully open at 102 C (216 F). The thermostat closes at
86 C (187 F).

ELECTRIC COOLING FAN

Caution: Keep hands, tools, and clothing away from
the engine cooling fans to help prevent personal in-
DAEWOO T-154 BL2,3