Page 268 of 715
08-31520-00
1. SPECIFICATION
Description Specification
Cooling system Type Water cooling, forced circulation
Coolant Capacity approx. 11.5 L
RadiatorCore size589W x 538H x 27T (over 3,170 cm²)
Flow type Cross flow
AntifreezeType Long life coolant
Mixing ratio
(water:antifreeze)50 : 50
Cooling fan
moduleMotor type DC motor
Motor weight 2.14 kg
Control type PWM type
Fan runout 3 mm
Coolant reservoirCapacity over 1.5 L
Circulation Closed roof type
Pressure cap Screw type
Pressure 1.4bar
ThermostatType Wax pallet type
Opening temperature90 ℃
Fully open temperature
100℃
Valve lift 8mm
Page 269 of 715

08-4
2. INSPECTION
Possible Cause Action
Coolant level
is
too low- Leak from the radiator
- Leak from the coolant auxiliary tank
- Leak from the heater core- Change the radiator
- Change the coolant auxiliary tank
- Change the heater
- Leak from the coolant hose
connections
- Damaged coolant hose - Reconnect the hose or replace
the clamp
- Change the hose
- Leak from the water pump gasket
- Leak from the water pump internal
seal- Change the gasket
- Change the water pump
- Leak from the water inlet cap
- Leak from the thermostat housing- Change the water inlet cap
gasket
- Change the thermostat sealing
- Incorrect tightening torque of the
cylinder head bolts
- Damaged cylinder head gasket- Tighten the bolts to the specified
torque
- Change the cylinder head gasket
Coolant
temperature is
too high- Coolant leakage (Coolant level is low)
- Improper coolant mixture ratio
- Kinked coolant hose- Add coolant
- Check the coolant concentration
(Anti-freeze)
- Repair or replace the hose
- Defective thermostat
- Defective water pump
- Defective radiator
- Defective coolant auxiliary tank or tank
cap- Change the thermostat
- Change the water pump
- Change the radiator
- Change the coolant auxiliary tank
or tank cap
- Cracks on the cylinder block or
cylinder head
- Clogged coolant passages in the
cylinder block or cylinder head- Change cylinder block or cylinder
head
- Clean the coolant passage
- Clogged radiator core - Clean the radiator core
- Improper operation of cooling fan - Replace the cooling fan or repair
the related circuit
- Defective temperature sensor or
faulty wiring- Replace the sensor or repair the
related wiring
Coolant
temperature is
too low- Thermostat is stuck open - Change the thermostat
- Improper operation of cooling fan - Replace the cooling fan or repair
the related circuit
- Defective temperature sensor or faulty
wiring- Replace the sensor or repair the
related wiring
Page 271 of 715
08-6
2) Leak Test
Release the pressure in the system by
loosening the pressure cap of the coolant
reservoir slightly. Then, remove the pressure
cap completely. 1.
Never open the cap until the coolant
temperature becomes under 90℃ to
prevent any burn.
Add the coolant so that the coolant level is
between MAX and MIN mark on the
coolant auxiliary tank.
Connect the tester to the tank filler and
apply pressure (1.4 bar).
Check all the coolant hoses, pipes and
connections for leaks when the pressure of
the tester drops, and replace or tighten, if
necessary. 2.
3.
4.
3) Thermostat
Immerse the thermostat into the water. Heat
the water and check the valve opening
temperature.
Valve opening
temperature 90 ± 2℃
Page 273 of 715
08-8
Coolant reservoir
Oil filter module
Thermostat
When the engine coolant
reaches 90℃, the thermostat
starts to open (fully open at
100℃) and lets the coolant
flow to the radiator to
maintain the engine
temperature.
Water pump
The water pump is driven by the engine drive belt and
supplies the coolant to each area of the engine.
1. SYSTEM DESCRIPTION
1) Overview
Water pump Impeller vaneSealing
Page 274 of 715
08-91520-00
Coolant temperature sensor
Measures the coolant
temperature and sends the
result to the engine ECU.
Electric fan
Circulates the fresh air forcibly to exchange
heat with the radiator core fin.
Radiator
Releases heat through fins and cools down the hot
coolant as the coolant passes through the tube of
the radiator core.
Page 287 of 715
10-4
1. OVERVIEW
The pre-heating system for D20DTR engine has the glow plug to the cylinder head (combustion
chamber), and improves the cold start performance and reduces the emission level.
The pre-heating resistor (air heater) is used to heat the intake air.
This enables the diesel fuel to be ignited in low temperature condition.
The ECU receives the information such as, engine rpm, coolant temperature, engine torque, etc.,
through CAN communication during pre-heating process; and the pre-heating control unit
controls the pre-heating, heating during cranking and post-heating by the PWM control.
Glow plug
Engine ECU (D20DTR)Glow indicator
Glow plug control unit
(GCU)
Page 290 of 715
10-71413-00
4) Operation
Glow plug is installed in the cylinder head. It enhances the cold starting performance and reduces
the exhaust gas during cold starting.
ECU receives the data (engine rpm, coolant temperature, vehicle speed) through CAN lines.
Based on the data, GCU controls the pre-glow, cranking and post-glow. It also checks the glow
plugs, and sends the result to ECU.
(1) Temperature/Current Properties of GCU
GCU increases the temperature of glow plug very rapidly (approx. 2 seconds up to
1000°C)
FETs (similar to transistor) for each cylinder are integrated in GCU. During the pre-
glow period, battery voltage is supplied to the glow plugs directly to heat them rapidly.
After getting the desired temperature by pre-glowing, the temperature is controlled by
duty ratio. Step 1:
Step 2 & 3:
Step 4:
This shows the supplying voltage and time by GCU in each step. The step 4 is the period to
keep the temperature. -Step 1: I1
Step 2: I2
Step 3: I3
Step 4: I4
Page 310 of 715
13-51793-00
EGR pipe
Transports the exhaust gas from the EGR
cooler and EGR bypass valve to the intake
duct.E-EGR valve
Receives the electric signal from the ECU to
control the valve.
E-EGR cooler and bypass valve
The cooler lowers the high temperature of the
exhaust gas and the bypass valve directly
supplies the exhaust gas to the intake duct
without passing through the EGR cooler to
reduce the emission of exhaust gas before
warming up the engine.HFM sensor
Used as a main map value to control the EGR.
The coolant temperature, engine rpm, engine
load, intake air temperature (HFM: decreased
at 60˚C or more), atmospheric pressure
(atmospheric pressure sensor: altitude
compensation) are used as auxiliary map
values.
2) Location and Components
See the section "Engine control" for E-EGR
valve control logic.EGR coolerEGR bypass
For details, see the section "Engine control". *