Isuzu N-Series. Manual - part 316

6A-6 ENGINE MECHANICAL

2) Apply a coat of engine oil to the bearing cap

bolt and stud threads.

3) Tighten the bearing cap bolts and studs to the

specified torque.

Tighten:
Camshaft bearing cap nut and bolt to 27 N

⋅m (2.8 kg⋅m

/ 20 lb

⋅ft)

6. Valve Cap

Apply engine oil to the inside of the valve caps and
install them to the valve stem end.

Caution:
Take sufficient care not to let valve caps fall into the
gear.

7. Rocker Arm Shaft Assembly

1) Temporarily tighten the bolts marked with the

arrow in the illustration.

2) Loosen the rocker arm adjust screws and apply

engine oil to the rocker arm roller portions.

3) Install the rocker arm assembly on the cylinder

head.

4) Tighten the rocker arm shaft bracket nuts and

bolts to the specified torque in numerical order
a little at a time as shown in the illustration.

Tighten:
Rocker arm shaft bracket nut and bolt to

• Nut (A): 27 N

⋅m (2.8 kg⋅m / 20 lb⋅ft)

• Bolt (B): 56 N

⋅m (5.7 kg⋅m / 41 lb⋅ft)

• Bolt (C): 27 N

⋅m (2.8 kg⋅m / 20 lb⋅ft)

N6A0109E

N6A0110E

N6A0111E

N6A0112E

ENGINE MECHANICAL 6A-7

5) Apply engine oil to the threaded portion of the

nuts marked with “A” and the bolts with “B”
shown in the illustration left, and tighten them to
the specified torque.

Adjust the valve clearance.

Above works refer to “SERVICING” “VALVE
CLEARANCE ADJUSTMENT” previously section
in this manual.

8. Injection Nozzle Holder Assembly

Tighten the nozzle holder flange nuts to the speci-
fied torque in the numerical order shown in the il-
lustration.

Tighten:
Nozzle holder flange nut to 19 N

⋅m (1.9 kg⋅m / 14 lb⋅ft)

9. Glow Plug

Tighten:
Glow Plug to 23 N

⋅m (2.3 kg⋅m / 17 lb⋅ft)

10. Glow Plug Connector

Valve Clearance

mm (in)

At cold

0.4 (0.016)

N6A0046E

N6A0114E

N6A0115E

6A-8 ENGINE MECHANICAL

VALVE SPRING, VALVE GUIDE OIL SEAL, VALVE, VALVE GUIDE

Component

Disassembly

Preparation

• Remove all the parts only with the cylinder head

assembly left.
(Above works refer to “CYLINDER HEAD GAS-
KET” section 6A3 in this manual.)

1. Cotter Collar

1) Place the cylinder head on a flat wooden sur-

face.

2) Use the valve spring compressor to remove the

cotter collar.

Do not allow the valve to fall from the cylinder
head.
Valve Spring Compressor: 5-8840-2228-0

2. Spring Upper Seat
3. Valve Spring

Legend

1. Split collar

4. Intake and exhaust valve

2. Spring upper seat

5. Valve guide seal

3. Valve spring

6. Spring lower seat

N6A0116E

ENGINE MECHANICAL 6A-9

4. Intake and Exhaust Valve

If the intake and exhaust valves are to be rein-
stalled, mark their installation positions by tagging
each valve with the cylinder number from which it
was removed.
If the intake and exhaust valves are to be replaced,
the valve guides must also be replaced.

5. Valve Guide Seal
6. Spring Lower Seat

Inspection and Repair

Make the necessary adjustments, repairs, and part re-
placements if excessive wear or damage is discovered
during inspection.

Valve Spring Free Height

Use a vernier caliper to measure the valve spring free
height.
If the measured valve is less than the specified limit, the
valve spring must be replaced.

N6A0117E

N6A0118E

Valve Spring Free Height
4HF1: 4HF1-2: 4HG1: 
4HG1-T

mm (in)

Nominal Size

Limit

62.5 (2.46)

59.4 (2.34)

4HE1-TC:

mm (in)

Nominal size

Limit

Intake Inner

53.2 (2.094)

50.1 (1.972)

Intake Outer

55.6 (2.189)

52.5 (2.067)

Exhaust Inner

58.6 (2.307)

55.5 (2.185)

Exhaust Outer

62.0 (2.441)

58.9 (2.319)

N6A0119E