Isuzu N-Series. Manual — part 318
6A-14 ENGINE MECHANICAL
2. Use a bench press (3) to gradually apply pressure
to the attachment and press the valve seat insert
into place.
Caution:
Do not apply an excessive amount of pressure with the
bench press. Damage to the valve seat insert will result.
3. The valve should be lapped before final assembly
to ensure a good valve seal.
Above works refer to “Valve Seat Insert Correction”
section in this manual.
Valve Seat Insert Correction
1. Remove the carbon from the valve seat insert sur-
face.
2. Use a valve cutter (15
°, 45°, and 75° blades) to
minimize scratches and other rough areas. This
will bring the contact width back to the standard
value. Remove only the scratches and rough ar-
eas. Do not cut away too much. Take care not to
cut away unblemished areas of the valve seat sur-
face.
Notice:
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 to see if the valve contact width is correct.
7. Check to see if the valve seat insert surface is in
contact with the entire circumference of the valve.
Reassembly
1. Spring Lower Seat
N6A0134E
N6A0135E
Valve Seat Angle
Degrees
45
°
N6A0136E
N6A0137E
ENGINE MECHANICAL 6A-15
2. Valve Guide Seal
1) Apply a coat of engine oil to the valve guide
seal inner face.
2) Use a valve guide seal installer to install the
valve guide seal to the valve guide
Valve Guide Seal Installer: 8-9439-6815-0
3. Intake and Exhaust Valve
1) Apply a coat of engine oil to each valve stem
before installation.
2) Install the intake and exhaust valve.
3) Turn the cylinder head up to install the valve
spring. Take care not to allow the installed
valves to fall free.
4. Valve Spring
Install the valve spring with its fine pitched (or
painted) end side down.
5. Spring Upper Seat
6. Cotter Collar
1) Use the valve spring compressor to push the
valve spring into position.
Valve Spring Compressor: 5-8840-2228-0
2) Install the cotter collar to the valve stem.
3) Set the cotter collar by tapping around the head
of the collar with a rubber hammer.
N6A0138E
N6A0139E
N6A0140E
N6A0141E
6A-16 ENGINE MECHANICAL
CAMSHAFT
Component
Disassembly
1. Rocker Arm Shaft Assembly
2. Valve Cap
3. Camshaft Bearing Cap
4. Camshaft Bearing Upper
5. Camshaft Assembly
6. Camshaft Bearing Lower
Above works refer to “CYLINDER HEAD” section
in this manual.
7. Camshaft Gear
Use the universal puller to pull out the camshaft
gear.
Universal puller: 5-8840-2027-0/5-8840-0086-0
8. Key
Legend
1. Rocker arm shaft assembly
5. Camshaft assembly
2. Valve cap
6. Camshaft bearing lower
3. Camshaft bearing cap
7. Camshaft gear
4. Camshaft bearing upper
8. Key
N6A0142E
N6A0143E
ENGINE MECHANICAL 6A-17
Inspection and Repair
Make the necessary adjustments, repairs, and part re-
placements if excessive wear or damage is discovered
during inspection.
Camshaft End Play
Use a thickness gauge to measure the clearance be-
tween the camshaft gear (1) and the camshaft bracket
(2).
If the measured value exceeds the specified limit, the
camshaft gear or the camshaft must be replaced.
Camshaft Journal Diameter
Use a micrometer to measure each camshaft journal di-
ameter in two directions ((1) and (2)). If the measured
value is less than the specified limit, the camshaft must
be replaced.
Cam Height
Measure the cam height “H” with a micrometer. If the
measured value is less than the specified limit, the cam-
shaft must be replaced.
Camshaft Run-Out
1. Mount the camshaft on V-blocks.
2. Measure the run-out with a dial indicator.
If the measured value exceeds the specified limit,
the camshaft must be replaced.
Camshaft End Play
mm (in)
Standard
Limit
0.085 — 0.205 (0.0033
— 0.0081)
0.25 (0.0098)
Camshaft Journal Diam-
eter
mm (in)
Standard
Limit
39.950 — 39.975
(1.5728 — 1.5738)
39.850 (1.569)
N6A0144E
Cam Height “H”
mm (in)
Engine model
Standard
Limit
Except 4HE1-
TC
52.8 (2.078)
51.8 (2.039)
4HE1-TC
53.6 (2.110)
52.6 (2.071)
Camshaft Run-Out
mm (in)
Limit
0.05 (0.002)
N6A0145E
N6A0146E
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