2004 ISUZU TF SERIES c24se

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

ENGINE DIAGNOSIS (C24SE) 6-9
Abnormal Noise Due to Hydraulic Lash Adjuster
Should abnormal noise due to the hydraulic lash
adjuster trouble be heard immediately after the engine
is started, inspect as follows:

Condition Possible cause Correction
Abnormal noise is heard Air contaminated Bleed
HLA is spongy Check ball valve broken Repair
Safety valve in cylinder head
broken Replace
Valve clearance is not zero HLA inside stick Replace HLA assembly

Troubleshooting Procedure
Short out each spark plug in sequence using insulated
spark plug wire removers. Locate cylinder with
defective bearing by listening for abnormal noise that
stops when spark plug is shorted out.

Condition Possible cause Correction
Noise from connecting rods or
from connecting rod bearings
(Faulty connecting rods or
connecting rod bearings usually
make an abnormal noise slightly
higher than the crank bearing
noise, which becomes more
evident when engine is
accelerated) Bearing or crankshaft pin worn Replace connecting rod bearings
and crankshaft or regrind
crankshaft and install the under
size bearing
Crankpin out of round Replace connecting rod bearings
and crankshaft or regrind
crankshaft and install the under
size bearing
Connecting rod bent Correct or replace
Connecting rod bearing seized Replace connecting rod bearings
and crankshaft or regrind
crankshaft and install the under
size bearing

Troubleshooting Procedure
Abnormal noise stops when the spark plug on the
cylinder with defective parts is shorted out.

Condition Possible cause Correction
Piston and cylinder
(Faulty piston or cylinder usually
makes a combined mechanical
thumping noise which increases
when engine is suddenly
accelerated but diminishes
gradually as the engine warms up) Piston clearance increased due to
cylinder wear Replace piston and cylinder body
Piston seized Replace piston and cylinder body
Piston ring broken Replace piston and cylinder body
Piston defective Replace pistons and others

6-10 ENGINE DIAGNOSIS (C24SE)
Troubleshooting Procedure

Condition Possible cause Correction
Piston pin noise
(Piston makes noise each time it
goes up and down) Piston pin or piston pin hole worn Replace piston, piston pin and
connecting rod assy

Troubleshooting Procedure
The slapping sound stops when spark plug on bad
cylinder is shorted out.

Condition Possible cause Correction
Timing belt noise Timing belt tension is incorrect Replace pusher or adjust the
tension pulley or replace timing
belt
Tensioner bearing defective Replace
Timing belt defective Replace
Timing wheels defective Replace
Timing belt comes in contact with
timing cover Replace timing belt and timing
cover
Valve noise Valve and valve guide seized Replace valve and valve guide
Valve spring broken Replace
Valve seat off-positioned Correct
Crankshaft noise Crankshaft end play excessive
(noise occurs when clutch is
engaged) Replace thrust bearing
Engine knocking Preignition due to use of spark
plugs of inadequate heat range Install Spark Plugs of adequate
heat range
Fuel too low in octane rating Replace fuel
Wide Open Throttle enrichment
system failure Refer to Section 6E
Selection of transmission gear
incorrect Caution operator or incorrect gear
selection
Engine overheating Refer to "Engine Lacks Power"
Others Water pump defective Replace
V-belt slipping Adjust tension of V-belt or replace
V-belt

ENGINE DIAGNOSIS (C24SE) 6-11
Abnormal Combustion
Condition Possible cause Correction
Trouble in fuel injection system Fuel pressure control valve
defective Replace
Fuel filter clogged Replace
Fuel pump clogged Clean or replace
Fuel tank or fuel pipe clogged Clean or replace
Fuel injector clogged Clean or replace
Fuel pump relay defective Replace
Power supply cable for fuel pump
loosely connected or defective Reconnect, correct or replace
Manifold Absolute Pressure
Sensor circuit open or shorted Correct or replace
Manifold Absolute Pressure
Sensor defective Replace
Engine Coolant Temperature
(ECT) Sensor circuit open or
shorted Correct or replace
ECT Sensor defective Replace
Throttle Position Sensor
adjustment incorrect Reconnect
Throttle Position Sensor defective Replace
Throttle Position Sensor
connector loosely connected Reconnect
Vehicle Speed Sensor cable
loosely connected or defective Correct or replace
Vehicle Speed Sensor loosely
fixed Fix tightly
Vehicle Speed Sensor in wrong
contact or defective Replace
Engine Control Module cable
loosely connected or defective Correct or replace
Trouble in emission control
system Heated Oxygen Sensor circuit
open (If applicable) Correct or replace
Heated Oxygen Sensor defective
(If applicable) Replace
Signal vacuum hose loosely fitted
or defective Correct or replace
ECT Sensor circuit open or
shorted Correct or replace
ECT Sensor defective Replace
Evaporative Emission Control
system (If applicable) Refer to Section 6E
Trouble in ignition system - Refer to "Engine Lacks Power"
Trouble in cylinder head parts Carbon deposits in combustion
chamber Remove carbon
Carbon deposit on valve, valve
seat and valve guide Remove carbon

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.

6-14 ENGINE DIAGNOSIS (C24SE)
Malfunction Indicator Lamp
The instrument panel "CHECK ENGINE" Malfunction
Indicator lamp (MIL) illuminates by self diagnostic
system when the system checks the starting of
engine, or senses malfunctions.

Condition Possible cause Correction
"CHECK ENGINE" MIL does not
illuminate at the starting of engine Bulb defective Replace
MIL circuit open Correct or replace
Command signal circuit to operate
self diagnostic system shorted Correct or replace
Engine Control Module (ECM)
cable loosely connected,
disconnected or defective Correct or replace
ECM defective Replace
“CHECK ENGINE” MIL
illuminates, and stays on Deterioration heated oxygen
sensor of internal element Replace
Heated oxygen sensor connector
terminal improper contact
(If applicable) Reconnect properly
Heated oxygen sensor lead wire
shorted (If applicable) Correct
Heated oxygen sensor circuit
open (If applicable) Correct or replace
Deterioration engine coolant
temperature sensor of internal
element Replace
Engine coolant temperature
sensor connector terminal
improper contact Reconnect properly
Engine coolant temperature
sensor lead wire shorted Correct
Engine coolant temperature
sensor circuit open Correct or replace
Throttle position sensor open or
shorted circuits Correct or replace
Deterioration of crankshaft
position sensor Replace
Crankshaft position sensor circuit
open or shorted Correct or replace
Vehicle speed sensor circuit open Correct or replace
Manifold absolute pressure sensor
circuit open or shorted Correct or replace
Intake air temperature sensor
circuit open or shorted Correct or replace
Fuel injector circuit open or shorted Correct or replace
ECM driver transistor defective Replace EPROM or ECM
Malfunctioning of ECM RAM
(Random Access Memory) or
Malfunctioning of ECM PROM
(Programmed Read Only Memory)Replace EPROM or ECM

ENGINE MECHANICAL (C24SE) 6A-1
SECTION 6A
ENGINE MECHANICAL
CONTENTS
PAGE
General Description......................................................................................................... 6A- 4
ENGINE PICTORIAL .................................................................................................... 6A- 6
Main Data and Specification ........................................................................................... 6A-11
CRANKCASE VENTILATION SYSTEM ....................................................................... 6A-16
ENGINE ASSEMBLY & LOOSE PARTS ..................................................................... 6A-17
OPERATIONS ON ENGINE AGGREGATES .................................................................... 6A-18
Engine Damping Blocks(Engine without Transmission)......................................... 6A-18
Toothed Belt and Timing Check ............................................................................... 6A-21
Toothed Belt Tension, Adjust .................................................................................... 6A-23
Toothed Belt, Replace ................................................................................................ 6A-24
OPERATIONS ON INSTALLED ENGINE ......................................................................... 6A-26
Gasket, Exhaust Manifold, Cylinder Head ................................................................ 6A-26
Gasket, Intake Manifold, Cylinder Head .................................................................... 6A-26
Seal Ring, Camshaft Housing, Timing Side .............................................................. 6A-27
Seal Ring, Thermostat Housing, Cylinder Head ....................................................... 6A-27
Seal Ring - Front Camshaft Housing, Replace ......................................................... 6A-28
Toother Belt Rear Cover ............................................................................................. 6A-30
Toother Belt Tension Roller ....................................................................................... 6A-31
COMPONENT PARTS ...................................................................................................... 6A-32
Cylinder Head .............................................................................................................. 6A-32
Hydraulic Valve Lifter.................................................................................................. 6A-33
OPERATIONS ON CYLINDER HEAD AND CAMSHAFT HOUSING ............................... 6A-34
Camshaft...................................................................................................................... 6A-34
Camshaft Housing Removal and Installation ........................................................... 6A-35
Cylinder Head .............................................................................................................. 6A-35
Hydraulic Valve Lifers, Replace ................................................................................. 6A-37
Camshaft Housing, Replace....................................................................................... 6A-37