1995 ISUZU TROOPER Workshop Manual

ENGINE DIAGNOSIS 6-15
MALFUNCTION INDICATOR LAMP
The instrument panei"CHECK ENGINE" Malfunction Indicator Lamp (MIL) illuminates by self diagnostic
system
when the system checks the bulb at the starting of engine, or senses malfunctions.
Complaint
Faulty parts
"CHECK
ENGINE" MIL
does not
illuminate
at the starting
of engine
"CHECK Heated Oxygen
ENGINE" MIL Sensor
illuminates,
and stays on
Engine
Coolant
Temperature Sensor
Throttle Position
Sensor
Crankshaft Position Sensor
Vehicle Speed
Sensor
Manifold
Absolute
Pressure Sensor
Intake Air
Temperature Sensor
Fuel Injector
ECM
Note: *1
-Random Access Memory
*2
-Read Only Memory
Possible cause Correction
Bulb defective Replace
MIL
circuit open Correct or replace
Command signal
circuit to operate self Correct or replace
diagnostic system shorted
Engine
Control Module (ECM) cable Correct or replace
loosely
connected, disconnected or
defective
ECM defective Replace
Deterioration of internal element Replace
Connector terminal improper contact Reconnect properly
Lead wire shorted Correct
Circuit
open Correct or replace
Deterioration of internal element Replace
Connector terminal improper contact Reconnect properly
Lead wire shorted Correct
Circuit
open Correct or replace
Open
or shorted circuits Correct or replace
Deterioration of sensor Replace
Open
or shorted circuit Correct or replace
Open
circuit Correct or replace
Open
or shorted circuit Correct or replace
Open
or shorted circuit Correct or replace
Open
or shorted circuit Correct or replace
Driver transistor defective Replace ECM
RAM*1 or ROM*2 malfunctioning Replace ECM

6-16 ENGINE DIAGNOSIS
ENGINE OIL PRESSURE CHECK
1. Check for dirt, gasoline or water in the engine
oil.
a. Change the oil if dirt, gasoline, or water
are present.
b. Check the viscosity of the oil.
c. Change the oil if the viscosity is outside
the specified standard.
d. 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 gage.
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:
7. Stop the engine.
392-550 kPa (56.9-80.4 psi)
at
3000 rpm.
8. Remove the oil pressure gage.
9. Install the oil pressure unit.
10. Start the engine and check for leaks.
m ... cw
•

ENGINE DIAGNOSIS 6-17
INSPECTION OF HYDRAULIC LASH ADJUSTER
• Should abnormal noise attributable to hydraulic lash adjuster trouble (entry of air) be heard immediately after
engine start inspect
as follows:
30-MINUTE AIR BLEEDING OPERATION AT 2500 RPM (UN-LOADED)
NO
"*SPONGY" HLAS?
(CONFIRM IN CONTACT WITH THE CAM BASE CIRCLE)
•
BLEED AIR FROM HLA (DOHC)
• RELIEF VALVE OR BLIND PLUG IN CYLINDER HEAD ARE NORMAL
START THE ENGINE WITH RELIEF VALVE REMOVED. THEN MAKE SURE THE OIL COMES UP, AND
THE OIL PRESSURE AT OIL
PRESSURE SWITCH 98 KPA (14.22 PSI) AT 2000 RPM
*SPONGY:
THE STATUS WITH CAM BE EASILY COMPRESSED BY A FINGER'S PUSH. •
REPLACE
ROCKER ARM ASSEMBLY
(SOHC)
• REPLACE
ONLY THE
HLA (DOHC) THE
NOISE IS NOT
DUE TO HLA
TROUBLE

'. ~ T' ' ~'
MEMO

GENERAL ENGINE MECHANICAL 6A-1
SECTION 6A
GENERAL ENGINE MECHANICAL
CONTENTS
Cylinder Head . . . . . . . . . . . . . . . . . . . . . . . . 6A-1
Valve Springs,
Oil Controller, Valve,
Valve Guide, (and HLA for
DOHC) . .

. . .
6A-4
Camshaft . .

. . . . . . . . . . . . . . . . . . . . . . . . . . GA-11
Rocker Arm Assembly . . . . . . . . . . . . . . . . .
GA-17
Oil Pump ............................ GA-20
Crankshaft ........................... GA-23
Piston and Connecting Rod ............. GA-30
Cylinder Block ........................ GA-37
CYLINDER HEAD
SOHC Model
2
Disassembly steps
1. Camshaft timing pulley 2. Front plate
3. Camshaft bracket fixing bolts 4. Camshaft, oil seal and camshaft end plug
5. Rockershaft assembly (Exhaust side)
6. Rockershaft assembly (Intake side) 7. Spark plug
Reassembly steps
To reassemble, follow the disassembly steps in the reverse order.
DOHC Model
2
1
~
Fig. 6A-1
Disassembly steps
1. Camshaft timing pulley 2. Front plate 3. Camshaft bracket fixing bolts 4. Chain tensioner fixing bolts
5. Camshaft, oil seal and camshaft end plug
6. Swing arm 7. Hydraulic lash adjusters (HLA)
8.
Spark plug
Reassembly steps To reassemble, follow the disassembly steps in the reverse order.

6A-2 GENERAL ENGINE MECHANICAL
NOTE:
•
During disassembly, be sure that the valve train
components are kept
together and identified so
that they can be re-installed in their original
locations.
• Before removing the cylinder head from the
engine and before disassembling the valve
mechanism, perform a compression test and note
the results.
1•! .. 1 DISASSEMBLY
(SOHC)
1. Camshaft timing pulley
2. Front plate
3. Camshaft bracket fixing bolts
4. Camshaft, oil seal and camshaft end plug
• Remove them with camshaft bracket.
5. Rockershaft assembly (Exhaust side)
6. Rockershaft assembly (Intake side)
7. Spark plug
\fl CAUTION:
VI • Do not remove the spark plugs when the head
and plugs are hot.
• Clean dirt and debris from spark plug recess
areas.
(DOHC)
1. Camshaft timing pulley
2. Front plate
3. Camshaft bracket fixing bolts
4. Chain tensioner fixing bolts
5. Camshaft, oil seal and camshaft end plug
• Remove them with chain and chain tensioner
6. Swing arm.
7. Hydraulic lash adjusters (HLA)
NOTE:
Immerse HLA in engine oil, taking care nottoturn it
upside down or sideways in order to prevent any
air
from entering into HLA.
8. Spark plug
\flCAUTION:
VI • Do not remove the spark plugs when the head
and plugs are hot.
• Clean dirt and debris from spark plug recess
areas.
f}l CLEAN
• Cylinder head
Carefully remove
all varnish, soot and carbon
to the bare metal. Do not use a motorized wire
brush on any gasket sealing surface.
IL'~'IINSPECTION AND REPAIR
• Cylinder head gasket and mating surfaces for
leaks, corrosion and blow-by. If the gasket has
failed, determine the cause. Insufficient
torque on head bolts
Improper installation
Loose
or warped cylinder head
Missing
dowel pins
- Warped case surface
1. Cylinder head bolts for damaged threads or
stretching and damaged heads caused by
improper use of tools.
\fl CAUTION:
VI Replace used cylinder head bolts.
2. Cylinder head for cracks, especially between valve
seats and in the exhaust ports.
3. Cylinder head deck for corrosion, sand particles in
head and porosity.
\fl CAUTION:
VI Do not attemptto weld the cylinder head. Replace
it.
4. Cylinder head deck, intake and exhaust manifold
mating surfaces for flatness (Fig. 6A-2). These
surfaces
may be re-conditioned by milling. If the
surfaces are
"out of flat" by more than
specification, the surface should be ground
to
within specifications. If more than repairable limit
of specification, it should be replaced.
5. Water jacket sealing plugs seating surfaces.
IIVD1-w 8~
~ I 0 I ' 0 0 I 0
mm (in)
Warpage
Maximum
Standard Repairable limit limit
Head surface 0.05 (0.002) 0.2
0.2
Manifold surface or less (0.00787) (0.00787)
SOHC 104.8 0.2
104.6
Head (4.1260) (0.00787) (4.1181)
height
DOHC 137.5 0.2 137.3
(5.4134)
(0.00787) (5.4055)
Fig. 6A-2
•