2004 ISUZU TF SERIES oil

6-2 ENGINE DIAGNOSIS (C24SE)
Engine Diagnosis
Hard Starting
1.Starting Motor Does Not Turn Over
Trouble Shooting Procedure
Turn on headlights and starter switch.
Condition Possible cause Correction
Headlights go out or dim
considerably Battery run down or under
charged Recharge or replace battery
Terminals poorly connected Clean battery posts and terminals
and connect properly
Starting motor coil circuit shorted Overhaul or replace
Starting motor defective Overhaul or replace
2.Ignition Trouble - Starting Motor Turns Over But Engine Does Not Start
Spark Test
Disconnect a high tension cable from any spark plug.
Connect the spark plug tester (use commercially
available tool), crank the engine, and check if a spark is
generated in the spark plug tester. Before cranking the
engine, make sure that the spark plug tester is properly
grounded. To avoid electrical shock, do not touch the
high tension cable while the engine is running.

Condition Possible cause Correction
Spark jumps across gap Spark plug defective Clean, adjust spark gap or replace
Spark plug wire in correct Connect properly or replace
Ignition timing incorrect Refer to Ignition System
Fuel not reaching fuel injector(s)
or engine Refer to item 3 (Trouble in fuel
system)
Valve timing incorrect Adjust
Engine lacks compression Refer to item 4 (Engine lacks
compression)
No sparking takes place Ignition coil disconnected or
broken Connect properly or replace
Electronic Ignition System with
module Replace
Poor connections in engine
harness Correct
Engine Control Module cable
disconnected or defective Correct or replace

ENGINE DIAGNOSIS (C24SE) 6-3
3.Trouble in Fuel System
Condition Possible cause Correction
Starting motor turns over and
spark occurs but engine does not
start. Fuel tank empty Fill
Water in fuel system Clean
Fuel filter clogged Replace filter
Fuel pipe clogged Clean or replace
Fuel pump defective Replace
Fuel pump circuit open Correct or replace
Evaporative Emission Control
system circuit clogged Correct or replace
Multiport Fuel Injection System
faulty Refer to "Electronic Fuel Injection"
section
4.Engine Lacks Compression
Condition Possible cause Correction
Engine lacks compression Spark plug loosely fitted or spark
plug gasket defective Tighten to specified torque or
replace gasket
Spark plug wire incorrect Connect properly or replace
Valve timing incorrect Adjust
Cylinder head gasket defective Replace gasket
Valve incorrectly seated Lap valve
Valve stem seized Replace valve and valve guide
Valve spring weakened Replace
Cylinder or piston rings worn Overhaul engine
Piston ring seized Overhaul engine.

Engine Compression Test Procedure
1. Start and run the engine until the engine
reaches normal operating temperature.
2. Turn the engine off.
3. Remove all the spark plugs.
4. Remove ignition coil fuse (15A) and disable the
ignition system.
5. Remove the fuel pump relay from the relay and
fuse box. 6. Engage the starter and check that the cranking
speed is approximately 300 rpm.
7. Install cylinder compression gauge into spark
plug hole.
8. With the throttle valve opened fully, keep the
starter engaged until the compression gauge
needle reaches the maximum level. Note the
reading.
9. Repeat the test with each cylinder.
The pressure difference between the individual
cylinders should not exceed 100kPa (14.5 psi).

ENGINE DIAGNOSIS (C24SE) 6-5
Rough Engine Running
Condition Possible cause Correction
Engine misfires regularly Ignition coil layer shorted Replace
Spark plugs fouling Clean or install hotter type plug
Spark plug(s) insulator nose
leaking Replace
Spark plug wire incorrect Connect properly or replace
Fuel injector(s) defective Replace
Engine control module faulty Replace
Engine knocks regularly Spark plugs running too hot Install colder type spark plugs
Powertrain control module faulty Replace
Engine lacks power Spark plugs fouled Clean
Spark plug wire incorrect Connect properly or replace
Fuel injectors defective Replace
Manifold Absolute Pressure
(MAP)
Sensor or Manifold Absolute
Pressure Sensor circuit defective Correct or replace
Engine Coolant Temperature
Sensor or Engine Coolant
Temperature Sensor circuit
defective Correct or replace
Engine Control Module faulty Replace
Intake Air Temperature Sensor or
Intake Air Temperature Sensor
circuit defective Correct or replace
Throttle Position Sensor or
Throttle Position Sensor circuit
defective Correct or replace
Knock Sensor or Knock Sensor
circuits defective Correct or replace
Knock Sensor Module or Knock
Sensor Module circuits defective Correct or replace

6-8 ENGINE DIAGNOSIS (C24SE)
Condition Possible cause Correction
Engine overheating Level of Engine Coolant too low Replenish
Thermo switch or fan motor
defective Replace
Thermostat defective Replace
Engine Coolant pump defective Correct or replace
Radiator clogged Clean or replace
Radiator filter cap defective Replace
Level of oil in engine crankcase
too low or wrong oil in engine Change or replenish
Resistance in exhaust system
increased Clean exhaust system or replace
defective parts
Throttle Position Sensor
adjustment incorrect Adjust Wide Open Throttle switch
setting
Throttle Position Sensor circuit
open or shorted Correct or replace
Cylinder head gasket damaged Replace
Cooling Fan clutch defective Replace
Fan belt slipping Adjust tension of V-belt or replace
V-belt
Engine overcooling Thermostat defective Replace (Use a thermostat set to
open at 92
C (197.6
F))
Engine lacks compression - Refer to Hard Start
Others Tire inflation pressure abnormal Adjust to recommend pressures
Brake drag Adjust
Clutch slipping Adjust or replace
Level of oil in engine crankcase
too high Correct level of engine oil

Engine Noisy
Abnormal engine noise often consists of various
noises originating in rotating parts, sliding parts and
other moving parts of the engine. It is, therefore,
advisable to locate the source of noise systematically.

Condition Possible cause Correction
Noise from crank journals or from
crank bearings
(Faulty crank journals and crank
bearings usually make dull noise
that becomes more evident when
accelerating) Oil clearance increased due to
worn crank journals or crank
bearings Replace crank bearings and
crankshaft or regrind crankshaft
and install the over size bearing
Crankshaft out of round Replace crank bearings and
crankshaft or regrind crankshaft
and install the over size bearing
Crank bearing seized Replace crank bearings and
crankshaft or regrind crankshaft
and install the over size bearing

6-12 ENGINE DIAGNOSIS (C24SE)
Engine Oil Consumption Excessive
Condition Possible cause Correction
Oil leaking Oil pan drain plug loose Retighten or replace gasket
Oil pan setting bolds loosened Retighten
Oil pan gasket broken Replace gasket
Front cover retaining bolts loose
or gasket broken Retighten or replace gasket
Head cover retaining bolts loose
or gasket broken Retighten or replace gasket
Oil filter adapter cracked Replace
Oil filter attaching bolt loose or
rubber gasket broken Retighten or replace oil filter
Crankshaft front or rear oil seal
defective Replace oil seal
Oil pressure unit loose or broken Retighten or replace
Blow-by gas hose broken Replace hose
Engine/Transmission coupling
area Replace oil seal
Oil leaking into combustion
chambers due to poor seal in
valve system Valve stem oil seal defective Replace
Valve stem or valve guide worn Replace valve and valve guide
Oil leaking into combustion
chambers due to poor seal in
cylinder parts Cylinders and pistons worn
excessively Rebore cylinder and replace
pistons and others
Piston ring gaps incorrectly
positioned Correct
Piston rings set with wrong side
up Correct
Piston rings sticking Rebore cylinder and replace
pistons and others
Piston ring and ring groove worn Replace pistons and others
Return ports in oil rings clogged Clean piston and replace rings
Crank case ventilation, Positive
Crankcase Ventilation System
malfunctioning Positive Crankcase Ventilation
Hose clogged Clean
Others Improper oil viscosity Use oil of recommended S.A.E.
viscosity
Continuous high speed driving
and or severe usage such as
trailer towing Continuous high speed operation
and or severe usage will normally
cause increased oil consumption

ENGINE DIAGNOSIS (C24SE) 6-13
Fuel Consumption Excessive
Condition Possible cause Correction
Trouble in fuel system Mixture too rich or too lean due to
trouble in fuel injection system Refer to "Abnormal Combustion"
Fuel cut function does not act Refer to "Abnormal Combustion"
Trouble in ignition system Misfiring or abnormal combustion
due to trouble in ignition system Refer to Hard Start or Abnormal
Combustion Troubleshooting
Guide
Others Engine idle speed too high Reset Idle Air Control Valve
Returning of accelerator control
sluggish Correct
Fuel system leakage Correct or replace
Clutch slipping Correct
Brake drag Correct
Selection of transmission gear
incorrect Caution operator of incorrect gear
selection
Oil Problems
Condition Possible cause Correction
Oil pressure too low Wrong oil in use Replace with correct engine oil
Relief valve sticking Replace
Oil pump not operating properly Correct or replace
Oil pump strainer clogged Clean or replace strainer
Oil pump worn Replace
Oil pressure gauge defective Correct or replace
Crankshaft bearing or connecting
rod bearing worn Replace
Oil contamination Wrong oil in use Replace with new engine oil
Oil filter clogged Replace oil filter
Cylinder head gasket damage Replace gasket
Burned gases leaking Replace piston and piston rings or
rebore cylinders
Oil not reaching valve system Oil passage in cylinder head or
cylinder body clogged Clean or correct

Engine Oil Pressure Check
1. Check for dirt, gasoline or water in the engine
oil.
a. Check the viscosity of the oil.
b. Change the oil if the viscosity is outside the
specified standard.
c. Refer to the "Maintenance and Lubrication"
section of this manual.
2. Check the engine oil level.
The level should fall somewhere between the
"ADD" and the "FULL" marks on the oil level
dipstick.
If the oil level does not reach the "ADD" mark on
the oil level dipstick, engine oil must be added. 3. Remove the oil pressure unit.
4. Install an oil pressure gauge.
5. Start the engine and allow the engine to reach
normal operating temperature (About 80
C).
6. Measure the oil pressure.
Oil pressure should be:
150 kPa(21.8 psi) at idle speed.
7. Stop the engine.
8. Remove the oil pressure gauge
9. Install the oil pressure unit.
10. Start the engine and check for leaks.

6A-2 ENGINE MECHANICAL (C24SE)
PAGE
Camshaft Housing, Check for Plance Surface ......................................................... 6A-39
Cylinder Head, Removal and Installation .................................................................. 6A-39
Cylinder Head, Disassemble and Assemble ............................................................. 6A-42
Valve, Grind ................................................................................................................. 6A-44
Valve Guide, Ream ..................................................................................................... 6A-44
Valve Seating, Mill ....................................................................................................... 6A-45
Cylinder Head, Overhaul............................................................................................. 6A-45
Flywheel ....................................................................................................................... 6A-46
Starter Ring Gear(Manual Transmission) ................................................................. 6A-47
Seal Ring, Crankshaft ................................................................................................. 6A-48
Seal Ring, Crankshaft Rear ........................................................................................ 6A-48
Oil Pan and Bearing Bridge........................................................................................ 6A-49
OPERATIONS ON CRANK DRIVE ................................................................................... 6A-51
Con-Rod Bearing......................................................................................................... 6A-51
Piston with Con-Rod ................................................................................................... 6A-51
Con-Rod ....................................................................................................................... 6A-52
Pistion Rings ............................................................................................................... 6A-53
OPERATIONS ON REMOVED ENGINE ........................................................................... 6A-55
Crankshaft ................................................................................................................... 6A-55
Bearing Free Play Measurement ................................................................................ 6A-57
Plastigage Method ...................................................................................................... 6A-57
Micrometer and gauge method .................................................................................. 6A-58
Bypass Valve ............................................................................................................... 6A-59
Oil Filter ....................................................................................................................... 6A-59
Oil Pump ...................................................................................................................... 6A-59
Oil Pump Safety Valve ................................................................................................ 6A-60
Oil Pump(Overhaul) .................................................................................................... 6A-60
OPERATIONS ON OIL CIRCULATION ............................................................................ 6A-61
Cylinder Head Safety Valve ........................................................................................ 6A-61
OPERATIONS ON COOLING SYSYTEM ......................................................................... 6A-63
Cooling System, Check for Leakes ........................................................................... 6A-63
Cooling System, Fill Up and Bleed ............................................................................ 6A-63
Refill Coolant ............................................................................................................... 6A-64
Ignition Timing, Check................................................................................................ 6A-64

ENGINE MECHANICAL (C24SE) 6A-3
PAGE
ENGINE EXTERNAL PARTS ............................................................................................ 6A-65
Radiator ....................................................................................................................... 6A-65
Thermostat................................................................................................................... 6A-66
Water Pump ................................................................................................................. 6A-66
Coating sealing surfaces with Silicone Grease ....................................................... 6A-67
Alternator ..................................................................................................................... 6A-67
Starter .......................................................................................................................... 6A-67
V-belt Tension of Alternator ....................................................................................... 6A-68
FUEL INJECTION SYSTEM.............................................................................................. 6A-69
Map Sensor.................................................................................................................. 6A-69
Pressure Regulator ..................................................................................................... 6A-69
ECM (Engine Control Module).................................................................................... 6A-69
ECT ............................................................................................................................... 6A-70
Idle Air Control(IAC) Valve.......................................................................................... 6A-70
Ignition Coil ................................................................................................................. 6A-70
Crank Position Sensor................................................................................................ 6A-71
FUEL INJECTOR .............................................................................................................. 6A-72
Knock Sensor .............................................................................................................. 6A-72
Oxygen Sensor ............................................................................................................ 6A-73
Throttle Valve Position Sensor .................................................................................. 6A-73
Acclelerator Pedal and Cable..................................................................................... 6A-73
Air Cleaner Filter ......................................................................................................... 6A-74
Spark Plug Thread ...................................................................................................... 6A-75
TECHNICAL DATA ........................................................................................................... 6A-76
Recommended Troque Values................................................................................... 6A-87
SPECIAL SERVICE TOOL................................................................................................ 6A-88