ISUZU TROOPER 1998 Service Repair Manual

ENGINE MECHANICAL 6A Ð 11
Valve Contact Width
1. Check the valve contact faces for roughness and
unevenness. Make smooth the valve contact sur-
faces.
2. Measure the valve contact width.
If the measured value exceeds the specified limit, the
valve seat insert must be replaced.
Valve Seat Insert Replacement
Valve Seat Insert Removal
1. Arc weld the entire inside circumference À of the
valve seat insert Á.
2. Allow the valve seat insert to cool for a few minutes.
This will invite contraction and make removal of the
valve seat insert easier.
3. Use a screwdriver  to pry the valve seat insert free.
Take care not to damage the cylinder head Ö .
4. Carefully remove carbon and other foreign material
from the cylinder head insert bore.
Valve Seat Insert Installation
1. Carefully place the attachment À (having a smaller
outside diameter than the valve seat insert) on the
valve seat insert Á .
Note:
The smooth side of the attachment must contact
the valve seat insert.
2. Use a bench press  to gradually apply pressure to
the attachment and press the valve seat insert into
place.
Note:
Do not apply an excessive amount of pressure with
the bench press. Damage to the valve seat insert
will result.
Valve Seat Insert Correction
1. Remove the carbon from the valve seat insert surface.
2. Use a valve cutter (15°, 45°, and 75° blades) to mini-
mize scratches and other rough areas. this will bring
the contact width back to the standard value.
Remove only the scratches and rough areas. Do not
cut away too much. Take care not to cut away un-
blemished areas of the valve seat surface.
Inlet
mm(in)
2.2 (0.0866)
Standard Limit
Exhaust1.7 (0.0669)
2.5 (0.0984) 2.0 (0.0787)

6A Ð 12 ENGINE MECHANICAL
3. Visually inspect both ends of the push rod for exces-
sive wear and damage. The push rod must be re-
placed if these conditions are discovered during
inspection.
REASSEMBLY
6. Valve Guide
·Apply engine oil to the outside of the valve guide.
Using special tool, drive in a new valve guide from
the cmashft side.
Valve guide replacer: 9-8523-1212-0
5. Valve Stem Oil Seal
·Using special tool, drive in a new oil seal
Oil special tool, drive in anew oil seal
Oil seal installer: 5-8840-2033-0
4. Valve
·Apply engine oil to the outside of the valve stem.
Push Rod Curvature
1. Lay the push rod on a surface plate.
2. Roll the push rod along the surface plate and measure
the push rod cuvature with a thickness gauge.
If the mesure value exceeds the specified limit, the
push rod must be replaced.
NOTE:
Use an adjustable valve cutter pilot.
Do not allow the valve cutter pilot to wobble inside the
valve guide.
3. Apply abrasive compound to the valve seat insert
surface.
4. Insert the valve into the valve guide.
5. Turn the valve while tapping it to fit the valve seat
insert.
6. Check that the valve contract width is correct.
7. Check that the valve seat insert surface is in contact
with the entire circumference of the valve.
mm(in)
0.3 (0.0118) Push Rod Curvature Limit
degree
45 Valve Seat Angle

ENGINE MECHANICAL 6A Ð 13
3. Valve Spring
·Attach the valve seat to the upper spring seat. The
painted area of the valve spring should be facing
downward.
2. Split Collar
·Use a spring compressor to push the valve spirng
into position.
·Install the spring seat split collar.
·Set the split collar by tapping lightly around the
head of the colar with a rubber hammer.
Valve spring compressor: 9-8523-1423-0 (J-29760)
1. Rocker Arm Assembly
N·m(Kg·m/lb·ft)
54 (5.5/40)

6A Ð 14 ENGINE MECHANICAL
CAMSHAFT, TAPPET
6. Camshaft Timing Gear
·Install the stopper bolt 1 to the timing pulley to
prevent it from turning.
·Use the timing pulley puller 2 to remove the
pulley.
Camshaft Timing Pulley Puller: 5-8840-0086-0
7. Camshaft Thrust Plate
DISASSEMBLY
1. Cylinder Head Assembly
2. Flywheel
3. Cylinder Block rear Plate
4. Crankcase Assembly
5. Oil Pump Assembly

ENGINE MECHANICAL 6A Ð 15
INSPECTION AND REPAIR
Make the necessary adjustments, repairs, and part replacements if excessive wear or damage is discovered
during inspection.
8. Camshaft
9. Tappet
1. Measure the Camshaft Thrust Clearance.
¥ Use a dial indicator to measure the camshaft end
play.
This must be done before removing the camshaft
gear.
If the camshaft end play exceeds the specified
limit, the thrust plate must be replaced.
2. Camshaft Journal Diameter
¥ Use a micrometer to measure each camshaft
journal diameter in two directions (1 and 2). If the
measured value is less than the specified limit,
the camshaft must be replaced.
3. Cam Height
¥ Measure the cam height H with a micrometer. If
the measured value is less than the specified
limit, the camshaft must be replaced.
Standard Limit
mm(in)
49.945-49.975 (1.9663-1.9675) 49.60 (1.9528) Journal Diameter
Standard Limit
mm(in)
42.02 (1.6543) 41.65 (1.6398) Cam Height
Standard Limit
mm(in)
0.08 (0.0031) 0.2 (0.0079) Camshaft End Play

6A Ð 16 ENGINE MECHANICAL
4. Camshaft Run-Out
¥ Mount the camshaft on V-blocks.
¥ Measure the run-out with a dial indicator.
If the measured value exceeds the specified limit,
the camshaft must be replaced.
5. Camshaft and Camshaft Bearing Clearance
¥ Use an inside dial indicator to measure the
camshaft bearing inside diameter.
Standard Limit
mm(in)
0.02 (0.0008) or less 0.10 (0.0039) Run-Out
¥ If the clearance between the camshaft bearing
inside diameter and the journal exceeds the
specified limit, the camshaft bearing must be
replaced.
Camshaft Bearing Replacement
Camshaft Bearing Removal
1. Remove the cylinder body plug plate.
2. Use the bearing replacer to remove the camshaft
bearing.
Bearing Replacer: 5-8840-2038-0
Camshaft Bearing Installation
1. Align the bearing oil holes with the cylinder body oil
holes.
2. Use the replacer to install the camshaft bearing.
Bearing Replacer: 5-8840-2038-0
Standard Limit
mm(in)
50.00 – 50.03
(1.9685 – 1.9697)50.08 (1.9716) Camshaft Bearing Inside Diameter
Standard Limit
mm(in)
0.025 – 0.085
(0.0010 – 0.0033)0.12 (0.0047) Camshaft Bearing Clearance

ENGINE MECHANICAL 6A Ð 17
REASSEMBLY
9. Tappet
1) Apply a coat of engine oil to the tappet and the
cylinder body tappet insert holes.
2) Locate the position mark applied at disassembly (if
the tappet is to be reused).
NOTE:
The tappet must be installed before the camshaft.
TAPPET
Visually inspect the tappet camshaft contact surfaces for
pitting, cracking, and other abnormal conditions. The
tappet must be replaced if any of these conditions are
present.
Refer to the illustration at the left.
1Normal contact
2Cracking
3Pitting
4Irregular contact
5Irregular contact
NOTE:
The tappet surfaces are spherical. Do not attempt to
grind them with an oil stone or similar tool in an effort to
repair the tappet. If the tappet is damaged, it must be
replaced.
Tappet Outside Diameter
1. Measure the tappet outside diameter with a microme-
ter. If the measured value is less than the specified
limit, the tappet must be replaced.
2. Measure the inside diameter tappet on the cylinder
block and calculate the clearance.
If the clearance exceeds the limit, replace tappet or/
and cylinder block.
Standard Limit
mm(in)
12.97 – 12.99
(0.5106 – 0.5114)12.95 (0.5098) Tappet Outside Diameter
Standard Limit
mm(in)
0.03 (0.0012) 0.10 (0.0039) Clearance Between Tappet and Cylinder Body

6A Ð 18 ENGINE MECHANICAL
8. Camshaft
1) Apply a coat of engine oil to the camshaft and the
camshaft bearings.
Install the camshaft to the cylinder body.
Take care not to damage the camshaft bearings.
7. Camshaft Thrust Plate
Install the thrust plate to the cylinder body and tighten the
thrust plate bolts to specified torque.
6. Camshaft Timing Gear
1) Install the camshaft timing gear to the camshaft.
The timing gear mark ("Y - Y") must be facing out-
ward.
2) Tighten the timing gear to the specified torque.
5. Oil Pump Assembly
¥ Refer to Section 6A2 ÒOil Pump InstallationÓ.
4. Crankcase Assembly
¥ Refer to Section 6A2 ÒCrankcaseÓ.
3. Cylinder Block Rear Plate
¥ Tighten cylinder block rear plate fixing bolts to the
specified torque.
18 (1.8/13)N·m(Kg·m/lb·ft)
64 (6.5/47)N·m(Kg·m/lb·ft)
82 (8.4/61)N·m(kg·m/lb·ft)
2. Flywheel
¥ Refer to Section 6A2 ÒCrankshaft InstallationÓ.
1. Cylinder Head Assembly
¥ Refer to Section 6A2 ÒCylinder Head InstallationÓ.

ENGINE MECHANICAL 6A Ð 19
ROCKER ARM ASSEMBLY
DISASSEMBLY
1. Rocker Arm Shaft Assembly
2. Rocker Arm Shaft Snap Ring
3. Rocker Arm
4. Rocker Arm Shaft Bracket
5. Rocker Arm
6. Rocker Arm Shaft Spring
7. Rocker Arm Shaft
INSPECTION AND REPAIR
Make the necessary adjustments, repairs, and part replacements if excessive wear or damage is discovered
during inspection.
Use a micrometer to measure the rocker shaft outside
diameter at the point where the rocker arm moves on the
rocker shaft.
Replace the rocker shaft if the diameter exceeds the
specified limit.
Standard Limit
mm(in) Rocker Arm Shaft Outside Diameter
18.98 – 19.00
(0.7472 – 0.7480)18.9 (0.7441)

6A Ð 20 ENGINE MECHANICAL
Oil Clearance
1. Use either a vernier caliper or a dial indicator to
measure the rocker arm inside diameter.
2. Measure the rocker arm shaft outside diameter.
If the measured value exceeds the specified limit,
replace either the rocker arm or the rocker arm shaft.
3. Check that the rocker arm oil port is free of obstruc-
tions.
If necessary, use compressed air to clean the rocker
arm oil port.
Rocker Arm Correction
Inspection the rocker arm valve stem contact surface for
step wear 1 and scoring 2.
If the contact surfaces have light step wear or scoring,
they may be honed with an oil stone.
If the step wear or scoring is severe, the rocker arm must
be replaced.
Rocker Arm Shaft Run-Out
1. Place the rocker arm shaft on a V-block.
2. Use a dial indicator to measure the rocker arm shaft
central portion run-out.
If the run-out is very slight, correct the rocker arm
shaft run-out with a bench press. The rocker arm
must be at cold condition.
If the measured rocker arm shaft run-out exceeds the
specified limit, the rocker arm shaft must be replaced.
0.3 (0.0118)
mm(in) Rocker Arm Shaft Run-Out
Limit
Standard Limit
mm(in)
19.01 – 19.03
(0.7484 – 0.7492)19.100 (0.7520) Rocker Arm Inside Diameter
Standard Limit
mm(in)
0.01 – 0.05
(0.0004 – 0.0019)0.20 (0.0079) Clearance Between Rocker Arm and
Rocker Arm Shaft