6E–349 ENGINE DRIVEABILITY AND EMISSIONS
Damage during re-gapping can happen if the gapping
tool is pushed against the center electrode or the
insulator around it, causing the insulator to crack.
When re-gapping a spark plug, make the adjustment
by bending only the ground side terminal, keeping the
tool clear of other parts.
”Heat shock” breakage in the lower insulator tip
generally occurs during several engine operating
conditions (high speeds or heavy loading) and may be
caused by over-advanced timing or low grade fuels.
Heat shock refers to a rapid increase in the tip
temperature that causes the insulator material to
crack.
Spark plugs with less than the recommended amount of
service can sometimes be cleaned and re-gapped , then
returned to service. However, if there is any doubt about
the serviceability of a spark plug, replace it. Spark plugs
with cracked or broken insulators should always be
replaced.
A/C Clutch Diagnosis
A/C Clutch Circuit Operation
A 12-volt signal is supplied to the A/C request input of the
PCM when the A/C is selected through the A/C control
switch.
The A/C compressor clutch relay is controlled through the
PCM. This allows the PCM to modify the idle air control
position prior to the A/C clutch engagement for better idle
quality. If the engine operating conditions are within their
specified calibrated acceptable ranges, the PCM will
enable the A/C compressor relay. This is done by
providing a ground path for the A/C relay coil within the
PCM. When the A/C compressor relay is enabled,
battery voltage is supplied to the compressor clutch coil.
The PCM will enable the A/C compressor clutch
whenever the engine is running and the A/C has been
requested. The PCM will not enable the A/C compressor
clutch if any of the following conditions are met:
The throttle is greater than 90%.
The engine speed is greater than 6315 RPM.
The ECT is greater than 119C (246F).
The IAT is less than 5C (41F).
The throttle is more than 80% open.
A/C Clutch Circuit Purpose
The A/C compressor operation is controlled by the
powertrain control module (PCM) for the following
reasons:
It improvises idle quality during compressor clutch
engagement.
It improvises wide open throttle (WOT) performance.
It provides A/C compressor protection from operation
with incorrect refrigerant pressures.
The A/C electrical system consists of the following
components:
The A/C control head.
The A/C refrigerant pressure switches.
The A/C compressor clutch.
The A/C compressor clutch relay.
The PCM.
A/C Request Signal
This signal tells the PCM when the A/C mode is selected
at the A/C control head. The PCM uses this to adjust the
idle speed before turning on the A/C clutch. The A/C
compressor will be inoperative if this signal is not
available to the PCM.
Refer to
A/C Clutch Circuit Diagnosis for A/C wiring
diagrams and diagnosis for A/C electrical system.
General Description (Exhaust Gas
Recirculation (EGR) System)
EGR Purpose
The exhaust gas recirculation (EGR) system is use to
reduce emission levels of oxides of nitrogen (NOx). NOx
emission levels are caused by a high combustion
temperature. The EGR system lowers the NOx emission
levels by decreasing the combustion temperature.
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Linear EGR Valve
The main element of the system is the linear EGR valve.
The EGR valve feeds small amounts of exhaust gas back
into the combustion chamber. The fuel/air mixture will be
diluted and combustion temperatures reduced.
Linear EGR Control
The PCM monitors the EGR actual positron and adjusts
the pintle position accordingly. The uses information from
the following sensors to control the pintle position:
Engine coolant temperature (ECT) sensor.
Throttle position (TP) sensor.
Mass air flow (MAF) sensor.
Linear EGR Valve Operation and Results
of Incorrect Operation
The linear EGR valve is designed to accurately supply
EGR to the engine independent of intake manifold
vacuum. The valve controls EGR flow from the exhaust
6A – 10 ENGINE MECHANICAL
8. Check the engine oil level and replenish to the
specified level if required.
9. Start the engine and check for oil leakage from the
main oil filter.
FUEL SYSTEM
Fuel filter
Replacement Procedure
1. Loosen the used fuel filter by turning it
counterclockwise with the filter wrench.
Filter Wrench : 5-8840-0203-0
2. Clean the filter cover fitting faces.
This will allow the new fuel filter to seat properly.
3. Apply a light coat of engine oil to the O-ring.
4. Turn the fuel filter until the sealing face comes in
contact with the O-ring.
5. Turn the fuel filter with a filter wrench 2/3 of a turn
until sealed.
Filter Wrench: 5-8840-0203-0Legend
(1) Priming pump
6. Operate the priming pump until the air is discharged
completely from fuel system.
NOTE: The use of an Isuzu genuine fuel filter is
strongly recommended.
COOLING SYSTEM
Coolant Level
Check the coolant level and replenish the radiator
reserve tank as necessary.
If the coolant level falls below the “‘MIN” line, carefully
check the cooling system for leakage. Then add
enough coolant to bring the level up to the “MAX” line.
NOTE: Do not overfill the reserve tank.
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ENGINE MECHANICAL 6A – 11
Remove the radiator filler cap only when absolutely
necessary.
Always check the coolant level when the engine is cold.
Always refer to the chart at the left to determine the
correct cooling water to antifreeze solution mixing ratio.
Cooling System Inspection
Install a radiator filler cap tester to the radiator. Apply
testing pressure to the cooling system to check for
leakage.
The testing pressure must not exceed the specified
pressure.
Testing Pressure: 196 kPa (2 kg/cm
2/28.45 psi)
Radiator Cap Inspection
The radiator filler cap is designed to maintain coolant
pressure in the cooling system at 103 kPa (1.05
kg/cm
2/15 psi).
Check the radiator filler cap with a radiator filler cap
tester.The radiator filler cap must be replaced if it fails to hold
the specified pressure during the test procedure.
Radiator Filler Cap Pressure Valve: 88.2 – 117.6 kPa
(0.899 – 1.199 kg/cm
2/12.8 – 17.1 psi)
Negative Valve (Reference): 1.0 – 3.9 kPa
(0.01 – 0.04 kg/cm
2/0.14 – 0.57 psi)
Thermostat Operating Test
1. Completely submerge the thermostat in water.
2. Heat the water.
Stir the water constantly to avoid direct heat being
applied to the thermostat.
3. Check the thermostat initial opening temperature.
Thermostat Initial Opening Temperature:
83 – 87°C (181 – 189°F)
4. Check the thermostat full opening temperature.
Thermostat Full Opening Temperature:
100°C (212°F)
Valve Lift at Fully Open Position: 9.5 mm (0.374
in)0
-10
-20
-30
-40
-50
-60
10 20 30
Mixing ratio (%)
Freezing point (
C)
40 50 60
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ENGINE MECHANICAL 6A – 33
INTAKE MANIFOLD
REMOVAL
1. Drain engine coolant and disconnect water hose
from thermostat hosing.
2. Remove intercooler assembly
Refer to “Intercooler” in this manual.
3. Remove bracket bolt of oil level gauge guide tube.
4. Remove PCV Hose.
5. Remove hoses from EGR, EGR vacuum sensor
and inlet/outlet of heater.
6. Disconnect harness connector form MAP sensor,
EGR vacuum sensor, ETC sensor, water
temperature unit, IAT sensor and EVRV.
7. Remove high pressure oil pipe.
8. Remove the two way valve.
9. Remove fuel pipe from between intake manifold
and high pressure oil pump.
10. Remove fixing bolts and nuts on the intake
manifold, then remove the intake manifold
assembly.
INSTALLATION
1. Install the intake manifold, tighten bolts and nuts to
the specified torque.
Torque : 20 Nꞏm (2.0 kgꞏm/14.5 lb ft) for bolt and nut
2. Install the fuel pipe and tighten to the specified
torque.To r q u e :
M16 bolt (apply engine oil) 4 Nꞏm (0.4 kgꞏm/2.9
lb ft)
Cap nut (M10) 13Nꞏm (1.3 kgꞏm/9.4 lb ft)
Fuel pipe (M10 apply engine oil) 14 Nꞏm (1.4
kgꞏm/10 lb ft)
3. Install two way valve.
Torque : 20 Nꞏm (2.0 kgꞏm/14.5 lb ft)
4. Fill with about 300 cc of engine oil from the high
pressure oil pipe installation port of the oil rail using
an oil filler. If assembled without filling the oil rail
with oil, the time for starting the engine will be
longer.
5. Install the high pressure oil pipe immediately and
tighten the sleeve nut to the specified torque.
Torque : 80 Nꞏm (8 kgꞏm/57.9 lb ft)
6. Reconnect harness connector to MAP sensor, EGR
vacuum sensor, ETC sensor, Water temperature
unit, IAT sensor and EVRV.
7. Connect the hoses to EGR valve, EGR vacuum
sensor, and water inlet/outlet pipe for heater.
8. Connect PCV hose.
9. Install the oil level gauge guide tube and tighten
bracket bolt.
10. Install the intercooler assembly.
Refer to “Intercooler” in this manual.
11. Connect the hose to the thermostat housing and fill
with engine coolant.
2
3
4
1
025RX001
Legend
(1) Intake Manifold
(2) Throttle Valve Assembly
(3) EGR Valve
(4) Gasket
6A – 40 ENGINE MECHANICAL
REMOVAL
1. Disconnect battery ground cable.
2. Drain engine coolant.
3. Remove air cleaner and air duct.
4. Remove intercooler assembly.
Refer to “Intercooler” in this manual.
5. Remove oil level gauge guide assembly.
6. Remove PCV hose.
7. Remove EGR vacuum hose.
8. Disconnect harness connector around the cylinder
head.
9. Remove A/C compressor assembly.
10. Remove A/C compressor bracket.
11. Remove generator assembly and take out fan belt.
12. Remove heat protector and remove valve
assembly.
13. Remove water hose and oil pipe from turbocharger.
14. Remove turbocharger assembly.
15. Remove water hose between thermostat and
radiator.
16. Remove cylinder head noise insulator cover.
NOTE: Do not make damage to the harness.
17. Remove high pressure pipe.
18. Remove timing belt cover.
19. Remove CMP sensor bracket.
20. Remove timing belt tensioner and remove timing
belt.
21. Remove camshaft pulley.
22. Remove front plate.
23. Remove water pipe between cylinder head and
water pump.
24. Remove fuel pipe between fuel pump and intake
manifold.
25. Remove fuel return pipe.
26. Remove intake manifold assembly.
27. Disconnect glow plug wiring and remove glow plug.
28. Remove cylinder head cover.
29. Drain oil from oil rail.
30. Disconnect injector harness connector.
31. Disconnect harness connector from oil pressure
sensor and oil temperature sensor on the oil rail.
32. Disconnect injector harness assembly.
33. Remove injector clamp.
34. Remove injector spacer.
35. Remove injector assembly.
36. Remove oil rail assembly.
37. Remove camshaft carrier.
38. Remove cylinder head assembly.
39. Remove cylinder gasket.
INSTALLATION
1. Install cylinder head gasket with top mark up.
NOTE: Determine cylinder head gasket grade by
measuring projection of piston head.2. Selection cylinder head gasket.
1) Measure the piston head projection by injector
gauge.
2) Measure the projection of piston head at the
nearest possible point to the cylinder bore.
3) Obtain the largest measurement from among all
cylinders.
4) Determine cylinder head gasket grade by
maximum value of measuring projection of
piston head.
Legend
(1) Top Mark
(2) Grade Mark
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6A – 42 ENGINE MECHANICAL
Legend
(1) Cylinder Head Noise Insulator Cover
(2) Insulator
(3) Bolt
(4) Oil Seal
(5) Gasket
(6) Cylinder Head Cover
(7) Bolt
21. Install water hose between thermostat and radiator.
22. Install turbocharger assembly to exhaust manifold.
Torque: 27 Nꞏm (2.8 kgꞏm/20.2 lb ft)
23. Install water hose and oil pipe for turbocharger.
24. Install exhaust valve assembly and heat protector.
Torque: 27 Nꞏm (2.8 kgꞏm/20.2 lb ft) for valve
Torque: 9 Nꞏm (0.9 kgꞏm/6.5 lb ft) for heat protector25. Install generator assembly.
Torque: 40 Nꞏm (4.0 kgꞏm/29 lb ft) for ACG bracket
Torque: 40 Nꞏm (4.0 kgꞏm/29 lb ft) between ACG and
bracket
Torque: 20 Nꞏm (2.0 kgꞏm/14.5 lb ft) between ACG
and adjuster plate
26.Fix the A/C compressor bracket and install A/C
compressor.
Torque: 47 Nꞏm (4.7 kgꞏm/34 lb ft) for A/C bracket
Torque: 20 Nꞏm (2.0 kgꞏm/14.5 lb ft) for belt tensioner
27. Reconnect harness connector around cylinder
head.
28. Connect EGR vacuum hose.
29. Install oil level gauge guide assembly.
Tighten nuts lower portion and tighten bolt.
Torque: 20 Nꞏm (2.0 kgꞏm/14.5 lb ft)
30. Install intercooler assembly.
Refer to “Intercooler” in this manual.
31. Install air duct between air cleaner and
turbocharger.
32. Fill engine coolant.
33. Reconnect battery.
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2
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4
5 6
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6A – 56 ENGINE MECHANICAL
VALVE STEM SEAL, VALVE SPRING AND ADJUSTER
REMOVAL
1. Disconnect battery ground cable.
2. Drain engine coolant.
3. Remove the air duct from between air cleaner and
turbocharger.
4. Remove intercooler assembly.
Refer to “Intercooler” in this manual.
5. Remove oil level gauge guide assembly.
6. Disconnect PCV hose.
7. Disconnect EGR vacuum hose.
8. Disconnect harness connectors around the cylinder
head such as the injector, CMP sensor, MAP
sensor, EGR sensor, EVRV, IAT sensor, A/C
compressor, TP stepping motor, TP sensor and fuel
temperature sensor etc.
9. Remove A/C compressor assembly.
10. Remove A/C compressor bracket.
11. Remove generator assembly and take out drivebelt.
12. Remove heat protector, remove exhaust valve
assembly.
13. Remove water cooling hose and lubrication pipe for
turbocharger.
14. Remove turbocharger assembly.
15. Remove hose between thermostat and radiator.
16. Remove noise insulator cover of cylinder head.
NOTE: Do not damage injector harness.
17. Remove high pressure oil pipe.
18. Remove timing belt cover.
19. Remove CMP sensor bracket.
20. Remove timing belt tensioner then remove timing
belt.
21. Remove camshaft pulley.
22. Remove front plate.
23. Remove engine coolant pipe between cylinder
head and water pump.
1
2
3
4
5
6
9
10
7
8
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Legend
(1) Adjuster
(2) Tappet
(3) Split Collar
(4) Spring Seat Upper
(5) Valve Spring(6) Spring Seat Lower
(7) Valve Stem Seal
(8) Valve Guide
(9) Valve Seat
(10) Valve
6A – 62 ENGINE MECHANICAL
INSTALLATION
1. Valve stem seal
1) Use the special tool to install the stem seal to the
valve guide.
Stem Seal Installer: 5-8840-2033-0
2. Valve spring.
1) Install the lower valve seat spring, valve spring,
then the upper valve spring seat.
2) Use valve spring compressor to compress the
spring then install the split collar.
Valve spring compressor: 5-8840-2441-0
NOTE: Make sure the split collar installs completely.
3. Install cylinder head assembly.
Refer to “Cylinder Head” in this manual.
4. Install the camshaft carrier with camshaft.
Refer to “Camshaft” in this manual.
5. Install oil rail assembly.
Refer to “Oil rail and injector” in this manual.
6. Install injector assembly.
Refer to “Oil rail and injector” in this manual.
7. Install the injector harness assembly.
Refer to “Injector” in this manual.
8. Reconnect harness connecter to oil pressure
sensor and oil temperature sensor on the oil rail.
9. Reconnect Injector harness connecter to injector.
Refer to “Injector” in this manual.
10. Install cylinder head cover with gasket.
Refer to “Cylinder Head Cover” in this manual.
11. Install glow plug with specified torque.
Torque: 15 Nꞏm (1.5 kgꞏm / 10.8 lb ft)
12. Install the intake manifold assembly.
Refer to “Intake Manifold” in this manual.
13. Install the fuel pipe.14. Install the water pipe between the cylinder head
and water pump.
Torque: 20 Nꞏm (2.0 kꞏm / 14.5 lb ft)
15. Install the front plate.
16. Install the camshaft pulley.
Refer to “Timing Gear” in this manual.
17. Install timing belt and set the tensioner.
Refer to “Timing Belt” in this manual.
18. Install CMP sensor bracket.
Torque: 20 Nꞏm (2.0 kgꞏm / 14.5 lb ft)
19. Install timing belt cover.
Torque: 9 Nꞏm (0.9 kgꞏm / 6.5 lb ft)
20. Fill the oil rail with engine oil then immediately
install the high pressure oil pipe with the specified
torque.
Torque: 80 Nꞏm (8.1 kgꞏm / 57.9 lb ft)
21. Install the noise insulator cover.
22. Reconnect hose between thermostat and radiator.
23. Install turbocharger assembly.
Refer to “Turbocharger” in this manual.
24. Install water hose and oil pipe for turbocharger.
Refer to “Turbocharger” in this manual.
25. Install the valve assembly and install heat protector.
26. Install generator and set the fan belts.
27. Install A/C compressor bracket, compressor
assembly and set drive belt.
28. Reconnect harness connector around cylinder
head.
29. Reconnect vacuum hose to EGR valve.
30. Reconnect PCV hose.
31. Install oil level gauge guide assembly.
32. Install intercooler assembly.
Refer to “Intercooler” in this manual.
33. Install the air duct assembly.
34. Fill engine coolant.
35. Connect battery ground cable.
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