Isuzu N-Series. Manual — part 565
GENERAL ENGINE MECHANICAL 6A-17
CAMSHAFT, TAPPET
Component
Disassembly
1. Cylinder Head Assembly
2. Flywheel
3. Cylinder Block Rear Plate
4. Oil Pan Assembly
5. Oil Pump Assembly
6. Camshaft Timing Gear (Gear Drive Model)
• Remove the camshaft timing gear bolt from the
camshaft.
Notice:
Hold the camshaft stationary to prevent the camshaft
from turning.
• Use the universal puller (1) to pull out the cam-
shaft timing gear (2).
• Universal Puller: 5-8521-0002-0
Remove the thrust plate (3).
Legend
1. Cylinder head assembly
7. Camshaft timing pulley
2. Flywheel
8. Camshaft thrust plate
3. Cylinder block rear plate
9. Camshaft pulley center
4. Oil pan assembly
10. Camshaft
5. Oil pump assembly
11. Tappet
6. Camshaft timing gear
N6A3092E
6A-18 GENERAL ENGINE MECHANICAL
7. Camshaft Timing Pulley (Belt Drive Model)
• Use the timing pulley puller (2) to remove the
pulley.
Timing Pulley Puller: 5-8840-0086-0
• Remove the stopper bolt.
8. Camshaft Thrust Plate (Gear Drive Model)
9. Camshaft Pulley Center (Belt Drive Model)
10. Camshaft
11. Tappet
Inspection and Repair
Make the necessary adjustment, repairs, and part re-
placements if excessive wear or damage is discovered
during inspection.
1. Measure the Camshaft Thrust Clearance
• Use a dial indicator to measure the camshaft
end play.
This must be done before removing the cam-
shaft 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.
N6A3093E
N6A3094E
Camshaft End Play
mm (in)
Standard
Limit
0.08 (0.0031)
0.2 (0.0079)
Journal Diameter
mm (in)
Standard
Limit
49.945 — 49.975 (1.9663 —
1.9675)
49.60 (1.9528)
N6A3095E
N6A3096E
GENERAL ENGINE MECHANICAL 6A-19
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.
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.
• 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
Cam Height
mm (in)
Standard
Limit
42.02 (1.6543)
41.65 (1.6398)
Run-Out
mm (in)
Standard
Limit
0.02 (0.008) or less
0.10 (0.0039)
N6A3097E
N6A3098E
Camshaft Bearing Inside Diameter
mm (in)
Standard
Limit
50.00 — 50.03 (1.9685 — 1.9696)
50.08 (1.9716)
Camshaft Bearing Clearance
mm (in)
Standard
Limit
0.025 — 0.085 (0.0010 — 0.0033)
0.12 (0.005)
N6A3099E
6A-20 GENERAL ENGINE MECHANICAL
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
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.
Notice:
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 re-
placed.
Tappet Outside Diameter
1. Measure the tappet outside diameter with a mi-
crometer. If the measured value is less than the
specified limit, the tappet must be replaced.
N6A3100E
N6A3101E
Legend
1. Normal contact
2. Cracking
3. Pitting
4. Irregular contact
5. Irregular contact
Tappet Outside Diameter
mm (in)
Standard
Limit
12.97 — 12.99 (0.510 — 0.511)
12.95 (0.509)
N6A3102E
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