Isuzu N-Series. Service manual — part 563
GENERAL ENGINE MECHANICAL 6A-9
• Apply a wrench as illustrated and tighten the
holder nut to the specified torque using a spe-
cial tool.
Caution:
• After tightening the holder nut, make sure that the
drilled hole makes
±5° or smaller with the cylinder
head-side positioning boss.
• When mounting leak off pipe, injection nozzle and
pipe, clean then with air so that dust may not enter.
Tighten:
Nozzle fixing to 64 N
⋅m (6.5 kg⋅m/47 lb⋅ft)
Wrench: Nozzle holder 5-8840-0259-0
9. Thermostat Housing Assembly
Tighten:
Thermostat housing assembly fixing bolt to 19 N
⋅m (1.9
kg
⋅m/14 lb⋅ft)
Legend
1. Glow plug
2. Positioning boss
N6A3072E
N6A3073E
6A-10 GENERAL ENGINE MECHANICAL
VALVE SPRING, VALVE GUIDE OIL SEAL, VALVE GUIDE, PUSH ROD
Component
Disassembly
1. Rocker Arm Assembly
2. Split Collar
Using special Tool, compress valve spring
Valve spring compressor: 9-8523-1423-0 (J-
29760)
3. Valve Spring
4. Valve
Legend
1. Rock arm assembly
4. Valve
2. Split collar
5. Valve guide oil seal
3. Valve spring
6. Valve guide
N6A3074E
N6A3075E
GENERAL ENGINE MECHANICAL 6A-11
5. Valve Guide Oil Seal
6. Valve Guide
Valve Guide Replacer: 9-8523-1212-0
Inspection and Repair
Make the necessary adjustments, repairs, and part re-
placements if excessive wear or damage is discovered
during inspection.
Valve spring
Caution:
Visually inspect the valve springs and replace them if
damage or abnormal wear is evident.
1. Free height
• Measure the free height of the springs. The
springs must be replaced if the height is below
the specified limit.
2. Squareness
• Measure the valve spring squareness with a
steel square.
• Replace the valve springs if the measured val-
ue exceeds the specified limit.
3. Spring tension
• Use spring tester to compress the springs to
the installed height. Measure the compressed
spring tension.
Replace the springs if the measured tension is
below the specified limit.
Valve Guide
Caution:
Taking care not to damage the valve seat contact sur-
face, when removing carbon adhering to the valve head.
Carefully inspect the valve stem for scratching or abnor-
mal wear. If these conditions are present, the valve and
the valve guide must be replaced as a set.
Free Height
mm (in)
Standard
Limit
48.0 (1.891)
47.100 (1.8560)
Limit
mm (in)
1.7 (0.067)
N6A3076E
Tension
N (kg/lb)
At installed height
38.9 mm (1.5 in)
Standard
Limit
296.2 (30.2/
66.6)
257.9 (26.3/
57.9)
N6A3077E
N6A3078E
6A-12 GENERAL ENGINE MECHANICAL
1. Valve Guide Clearance
• Measure the valve stem diameter with a mi-
crometer.
If the valve stem diameter is less than the spec-
ified limit, the valve and the valve guide must be
replaced as a set.
• Measure the inside diameter of the valve guide
with a micrometer.
• Subtract the measured outer diameter of the
valve stem from the measured inner diameter
of the valve guide. If the valve exceeds of the
valve guide.
If the valve exceeds the specified limit, the
valve and the valve guide must be replaced as
a set.
Valve Guide Replacement
1. Using special tool, drive out the valve guide from
the combustion chamber side.
Valve guide replacer: 9-8523-1212-0
2. Apply engine oil to the outside of the valve guide.
Using special tool, drive in a new valve guide from
cylinder head upper face side, and check the valve
guide height.
Valve guide replacer: 9-8523-1212-0
Notice:
If the valve guide has been removed, both the valve and
the valve guide must be replaced as a set.
mm (in)
Standard
Limit
Diameter of
Valve stem
Inlet
7.946 — 7.961
(0.3128 —
0.3134)
7.880
(0.310.2)
Exhaust
7.921 — 7.936
(0.3118 —
0.3124)
7.850
(0.3091)
Valve Guide Clearance
mm (in)
Standard
Limit
Inlet clearance
0.039 — 0.069
(0.0015 —
0.0027)
0.200
(0.0079)
Exhaust clearance
0.064 — 0.096
(0.0025 —
0.0038)
0.250
(0.0098)
N6A3079E
Height
mm (in)
13 (0.51)
N6A3080E
N6A3067E
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст