Page 212 of 828
04-51719-00
3) Troubleshooting Sequence
The basic checks for intake system are as follows:
Basic Checks for Intake System ▶
Make sure to replace or clean the air
cleaner element periodically. Otherwise,
engine will be derated or work abnormally
because of low intake air volume.
Unlike the fuel system, which is a closed
circuit, the intake system is an open circuit
system. Therefore any malfunction may
occur due to dust and dirt.
Most of the connections consist of hoses
so the system cannot withstand high
temperature and pressure. Also it can be
deformed or loosened easily because it is a
clamp mounting system. Thus, when
checking the engine, basic inspections,
such as tightened status check and visual
inspection for hose, etc., should be carried
out in advance.
Other Checks for Intake System ▶
If the intake system is free of any faults,
check for EGR and PCV oil separator.
Page 224 of 828

06-4
2. INSPECTION
1) Cautions During Driving
The following lists cautions to take during test drive and on the turbocharger vehicle, which must
be considered during the operation.
It's important not to drastically increase the engine rpm starting the engine. It could make
rotation at excessive speed even before the journal bearing is lubricated and when the
turbocharger rotates in poor oil supply condition, it could cause damage of bearing seizure
within few seconds.
If the engine is running radically after replacing the engine oil or oil filter brings poor oil supply
condition. To avoid this, it's necessary to start off after idling the engine for about 1 minute
allowing oil to circulate to the turbocharger after the replacement.
When the engine is stopped abruptly after driving at high speed, the turbocharger continues to
rotate in condition where the oil pressure is at '0'. In such condition, an oil film between the
journal bearing and the housing shaft journal section gets broken and this causes abrasion of
the journal bearing due to the rapid contact. The repeat of such condition significantly reduces
life of the turbocharger. Therefore, the engine should be stopped possibly in the idle condition. 1.
2.
3.
After string for long period of time during winter season or in the low temperature condition
where the fluidity of engine oil declines, the engine, before being started, should be cranked to
circulate oil and must drive after checking the oil pressure is in normal condition by idling the
engine for few minutes.
Page 225 of 828

06-50000-00
2) Inspection of Turbocharger
When problem occurs with the turbocharger, it could cause engine power decline, excessive
discharge of exhaust gas, outbreak of abnormal noise and excessive consumption of oil.
On-board Inspection 1.
Check the bolts and nuts foe looseness or missing
Check the intake and exhaust manifold for looseness or damage
Check the oil supply pipe and drain pipe for damages
Check the housing for crack and deterioration -
-
-
-
Inspection of turbine 2.
Remove the exhaust pipe at the opening of the turbine and check, with a lamp, the existence of
interference of housing and wheel, oil leakage and contamination (at blade edge) of foreign
materials.
Interference: In case where the oil leak sign exists, even the small traces of interferences on
the turbine wheel mean, most of times, that abrasion has occurred on the journal bearing.
Must inspect after overhauling the turbocharger.
Oil Leakage: Followings are the reasons for oil leakage condition -
-
Idling for long period of time can cause oil leakage to the turbine side due to low pressure of
exhaust gas and the rotation speed of turbine wheel. Please note this is not a turbocharger
problem.
Oil Drain Pipe Defect
In case where oil flow from the turbocharger sensor housing to the crank case is not smooth
would become the reason for leakage as oil builds up within the center housing. Also, oil
thickens (sludge) at high temperature and becomes the indirect reason of wheel hub section. In
such case, clogging and damage of the oil drain pipe and the pressure of blow-by gas within
the crank case must be inspected.
Damages due to Foreign Materials
When the foreign materials get into the system, it could induce inner damage as rotating
balance of the turbocharger gets out of alignment. -
-Problems in engine: In case where the oil is smeared on inner wall section of the exhaust
gas opening.
Problems in turbocharger: In case where the oil is smeared on only at the exhaust gas
outlet section. *
*
Page 243 of 828

07-31543-00
1. SPECIFICATION
The engine oil filter element should be changed at the same time with the engine oil.
Regularly check the engine oil level and add the engine oil if necessary.
Remember to check the engine oil level and shorten the cycle to replace the engine oil
under severe driving conditions. -
-
Severe Driving Condition
Frequent stop-and-go traffic, extended idling, short driving distance below 6 km, driving
distance below 16 km when the outside temperature remains below freezing
Driving in a hilly or mountainous terrain, sandy, or dusty area
High load driving such as trailer towing
Taxi, patrol service or delivery service (extended idling and excessive driving with low
speed) -
-
-
-
Unit Specification
Oil pump Lubrication system Gear pump, forced circulation
Type Inscribed gear
Capacity 63 L at 4,000 rpm
Relief pressure5.8 bar ± 0.3 bar
Oil filter Type Full flow/Paper element
Engine oil Specified oil SAE 5W30 (approved by MB SHEET 229.51)
Capacity (L) Min.: 4.5 L
Max.: 6.0 L
Service interval Change every 15,000 km or 12 months (But,
shorten the service interval under severe
condition)
Oil injection
nozzleType Piston
Operating pressure 1.5bar
Closing pressure 1.0bar
Oil flow 4 L/min
Permissible pressure 10bar
Unit Specification
Oil pump Lubrication system Gear pump, forced circulation
Type Inscribed gear
Capacity 63 L at 4,000 rpm
Relief pressure5.8 bar ± 0.3 bar
Oil filter Type Full flow/Paper element
Engine oil Specified oil SAE 5W30 (approved by MB SHEET 229.51)
Capacity (L) Min.: 4.5 L
Max.: 6.0 L
Service
intervalEU Change every 20,000 km or 12 months
(The service interval should be shortened under
severe conditions)
General Change every 15,000 km or 12 months
(The service interval should be shortened under
severe conditions)
Oil pressure
switch
Page 245 of 828
07-51543-00
1. SYSTEM DESCRIPTION
1) Overview
The lubrication system supplies oil to each lubrication section to prevent friction and wear and to
remove heat from the friction part. As the engine runs, frictional heat is generated on each
lubrication section. If this condition persists, the bearing can be burned and stuck.
In other words, it creates an oil film on each sliding surface to convert solid friction to liquid
friction in order to minimize wear and prevent temperature increasing on the friction part.
For the D20DTF engine with no oil pressure switch, the engine ECU receives the low engine oil
level signal from the oil level sensor and communicates with the instrument cluster through the
CAN communication to turn on the warning lamp.
2) Components
Oil coolerOil dipstick gaugeOil pump
Oil filter moduleOil pressure switchOil pan
Page 251 of 828
08-8
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.
Coolant reservoir
Long life coolant is used.
1. SYSTEM DESCRIPTION
1) Overview
Water pump
Impeller vane Sealing
Page 312 of 828

15-90000-00
2) ECU Control
(1) Function
a. ECU Function
ECU receives and analyzes signals from various sensors and then modifies those signals into
permissible voltage levels and analyzes to control respective actuators.
ECU microprocessor calculates injection period and injection timing proper for engine piston
speed and crankshaft angle based on input data and stored specific map to control the engine
power and emission gas.
Output signal of the ECU microprocessor drives pressure control valve to control the rail pressure
and activates injector solenoid valve to control the fuel injection period and injection timing; so
controls various actuators in response to engine changes. Auxiliary function of ECU has adopted
to reduce emission gas, improve fuel economy and enhance safety, comforts and conveniences.
For example, there are EGR, booster pressure control, autocruise (export only) and immobilizer
and adopted CAN communication to exchange data among electrical systems (automatic T/M
and brake system) in the vehicle fluently. And Scanner can be used to diagnose vehicle status
and defectives.
<00760097008c00990088009b00900095008e0047009b008c00940097008c00990088009b009c0099008c0047009900880095008e008c00470096008d0047006c006a007c00470090009a0047009500960099009400880093009300a000470054005b005700
47009b009600470052005f005c00b6006a004700880095008b> protected from factors like oil,
water and electromagnetism and there should be no mechanical shocks.
To control the fuel volume precisely under repeated injections, high current should be applied
instantly so there is injector drive circuit in the ECU to generate necessary current during injector
drive stages.
Current control circuit divides current applying time (injection time) into full-in-current-phase and
hold-current-phase and then the injectors should work very correctly under every working
condition.
b. Control Function
Controls by operating stages
To make optimum combustion under every operating stage, ECU should calculate proper
injection volume in each stage by considering various factors.
Starting injection volume control
During initial starting, injecting fuel volume will be calculated by function of temperature and
engine cranking speed. Starting injection continues from when the ignition switch is turned to
ignition position to till the engine reaches to allowable minimum speed.
Driving mode control
If the vehicle runs normally, fuel injection volume will be calculated by accelerator pedal travel
and engine rpm and the drive map will be used to match the drivers inputs with optimum
engine power. -
-
-
Page 340 of 828

15-370000-00
HFM (intake air
temperature)Cooling fan module
DSI 6 A/T (ATF
temperature)Coolant
temperature senso
r
Refrigerant
pressure sensor
Relay box
(12) Cooling fan control
A. Overview of cooling fan and A/C compressor
The cooling system maintains the engine temperature at an efficient level during all engine
operating conditions. The water 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. The heat from automatic transmission
is also cooled down through the radiator by circulating the oil through the oil pump. ECU controls
the electric cooling fans with three cooling fan relays to improve the engine torque and air
conditioning performance.
For detailed information, refer to Chapter "Air Conditioning System".
B. Components
A/C compressor
D20DTR ECU