Isuzu N-Series. Manual — part 489
Engine Mechanical (4HK1-TC) 6A-61
Camshaft Assembly
Component
Legend
1. Bearing Cap
2. Bearing
3. Knock Pin
4. Snap Ring
5. Dish Washer
6. Sub Gear
7. Spring
8. Camshaft Gear
Removal
1. Rotate the crank shaft to make the No. 1 cylinder
meet the compression TDC.
2. Remove the cylinder head cover.
Refer to the “cylinder head cover.”
3. Remove the rocker arm shaft assembly.
Refer to the “rocker arm shaft assembly.”
4. Remove the camshaft bearing cap.
1
2
3
4
5
6
7
8
N6A6096E
6A-62 Engine Mechanical (4HK1-TC)
• Before removing the camshaft from the cylinder
head, rotate the sub gear using the special tool
to prevent the spring force which acts on the
sub gear from affecting. Align the hole of the
sub gear with the camshaft main gear and
install the phase alignment pin from the sub
gear side to match the teeth.
Special tool
Scissors gear spring wrench: 5-8840-2674-0
5. Remove the bearing upper.
6. Remove the camshaft assembly.
7. Remove the bearing lower.
Caution:
Put the removed bearings in order with a tag, for
example, by cylinder.
Disassembly
1. Remove the scissors gear assembly.
• Fix the hexagon portion of the camshaft in a
vise using a mouth ring. Use snap ring pliers to
remove the sub gear.
Caution:
Take care not to damage to the cam portion and the
journal portion of the camshaft.
Legend
1. Snap Ring
2. Dish Washer
3. Sub Gear
4. Spring
5. Camshaft Gear
N6A6660E
N6A6097E
N6A6098E
1
2
3
4
5
N6A6099E
Engine Mechanical (4HK1-TC) 6A-63
2. Remove the camshaft gear.
• Remove the fastening bolts of the camshaft
gear and put the block of wood in a puller to
remove the camshaft gear.
Legend
1. Wood
3. Remove the dowel pin.
4. Inspect the camshaft visually.
• Check if the journal and cam parts of the
camshaft are worn or damaged, if so, replace it.
5. Inspect an end clearance of the camshaft.
• Use a thickness gauge to measure an end
clearance of the camshaft gear and the
camshaft bracket.
• If the measurement exceeds the limit, replace
the camshaft gear or the camshaft.
Caution:
Measure an end clearance of the camshaft before
disassembling.
6. Check if the cam lobe is worn.
• Measure the height “H” of the cam lobe with a
micrometer.
• If the height of the cam lobe is the limit or less,
replace the camshaft.
N6A6100E
N6A6101E
End clearance of the camshaft
mm (in)
Standard
0.085 – 0.205 (0.033 – 0.008)
Limit
0.25 (0.009)
Height of the cam lobe
mm (in)
Inlet
Exhaust
Standard
52.8 (2.08)
54.5 (2.15)
Limit
51.8 (2.04)
53.5 (2.11)
N6A6102E
6A-64 Engine Mechanical (4HK1-TC)
7. Check if the camshaft journal is worn.
• Use a micrometer to measure wear which is not
even with a diameter of the camshaft journal.
• If the measured uneven wear exceeds the limit,
replace the camshaft.
8. Check if the camshaft is warpage.
• Place the camshaft on a V block to measure a
runout with a dial gauge.
• Rotate the camshaft slowly and measure the
range of fluctuation. If it exceeds the limit,
replace the camshaft.
9. Measure camshaft journal oil clearance.
a. Measure the inside diameter of the camshaft
bearing with a dial gauge.
b. Read the difference between the inside
diameter of the camshaft bearing and the
diameter of the camshaft journal.
If the measured oil clearance exceeds the limit,
replace the camshaft bearing.
External diameter of the camshaft journal
part
mm (in)
Standard
39.950 – 39.975 (1.5728 – 1.5738)
Limit
39.850 (1.5688)
Partial wear of the camshaft journal part
mm (in)
Limit
0.05 (0.0019)
H
N6A6652E
N6A6104E
Warpage of the camshaft
mm (in)
Limit
0.05 (0.0019 )
Clearance of the journal part
mm (in)
Standard
0.025 – 0.087 (0.0009 – 0.0034)
Limit
0.15 (0.0059)
N6A6105E
N6A6106E
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