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