Isuzu N-Series. Manual - part 321

6A-26 ENGINE MECHANICAL

7. Cotter Pin
8. Spring Seat
9. Oil Relief Valve Spring

10. Oil Relief Valve
11. Pump Cover

Inspection and Repair

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

Gear Teeth and Cover Inner Wall Clearance

Use a feeler gauge to measure the clearance between
the gear teeth and the cover inner wall.
If the clearance between the gear teeth and the cover in-
ner wall exceeds the specified limit, the oil pump assem-
bly must be replaced.

Gear and Cover Clearance

Use a feeler gauge to measure the clearance between
the cover and the gear.
If the clearance between the gear and the cover ex-
ceeds the specified limit, the oil pump assembly must be
replaced.

Driven Gear Shaft and Bushing Clearance

1. Use a micrometer to measure the gear shafts out-

side diameter.

Gear Teeth and Cover 
Inner Wall Clearance

mm (in)

Standard

Limit

0.125 — 0.220 (0.0049 

— 0.0087)

0.3 (0.012)

N6A0169E

Gear and Cover Clear-
ance

mm (in)

Standard

Limit

0.064 — 0.109 (0.0025 

— 0.0043)

0.2 (0.008)

N6A0170E

N6A0171E

ENGINE MECHANICAL 6A-27

2. Use an inside dial indicator or inside micrometer to

measure the pump cover bushing inside diameter
and the cylinder body inside diameter.
If clearance between the gear shaft and the bush-
ing exceeds the specified limit, the oil pump as-
sembly must be replaced.

Reassembly

1. Pump Cover
2. Oil Relief Valve
3. Oil Relief Valve Spring
4. Sprig Seat
5. Cotter Pin

6. Driven Gear and Shaft

Apply the engine oil to the driven gear shaft.

7. Oil Pump Assembly

1) Carefully wipe any foreign material from cylin-

der body rear surface.

2) Apply the recommended liquid gasket (Three

Bond 1141E) or its equivalent to the shaded ar-
eas shown in the illustration.

Caution:
Be careful that no liquid gasket gets into the holes in the
arrow-marked portion in the illustration and the inside of
the oil pump cover.

Gear Shaft Outside 
Diameter

mm (in)

Standard

Limit

15.989 —16.000 (0.6295 

— 0.6299)

15.9 (0.626)

Gear Shaft and Bushing 
Clearance

mm (in)

Standard

Limit

0.04 — 0.07 (0.0016 — 

0.0028)

0.2 (0.012)

N6A0172E

N6A0173E

N6A0174E

N6A0175E

6A-28 ENGINE MECHANICAL

3) Install the oil pump to the cylinder body.
4) Tighten the oil pump to the specified torque.

Tighten:
Oil pump bolt to 31 N

⋅m (3.2 kg⋅m / 23 lb⋅ft)

8. Idle Gear A

1) Turn the crankshaft clockwise so that the en-

gagement mark of the crankshaft gear faces to
the shaft center of the idle gear A and the No.1
cylinder piston comes to the top dead center.

2) Align the crankshaft gear with the engagement

mark of the idle gear and install the idle gear A.

Tighten:
Idle gear A bolt to 133 N

⋅m (13.6 kg⋅m / 98 lb⋅ft)

9. Flywheel Housing

1) Carefully wipe any foreign material from the cyl-

inder body rear face.

2) Apply the recommended liquid gasket (Three

Bond 1207C) or its equivalent to the shaded ar-
eas shown in the illustration.

N6A0176E

N6A0177E

N6A0178E

N6A0179E

ENGINE MECHANICAL 6A-29

3) Align the cylinder body knock pins with the fly-

wheel housing knock pin holes.

4) Tighten the flywheel housing bolts to the spec-

ified torque shown in the illustration.

Tighten:
Flywheel housing bolt to

• A: 96 N

⋅m (9.8 kg⋅m / 71 lb⋅ft)

• B: 48 N

⋅m (4.9 kg⋅m / 35 lb⋅ft)

• C: 94 N

⋅m (9.6 kg⋅m / 69 lb⋅ft)

• D: 25 N

⋅m (2.6 kg⋅m / 19 lb⋅ft)

• E: 76 N

⋅m (7.7 kg⋅m / 56 lb⋅ft)

• F: 38 N

⋅m (3.9 kg⋅m / 28 lb⋅ft)

• Tighten the bolts marked with “E” or “B” from

the injection pump side, and those with “F” from
the cylinder body side.

Tighten:
Flywheel housing bolt (G) to 96 N

⋅m (9.8 kg⋅m / 71 lb⋅ft)

10. Power Steering Pump Idle Gear

1) Apply the engine oil to the idle gear shaft.
2) Install the idle gear shaft (1) with the idle gear

(2) to the cylinder body “A” portion as shown in
the illustration.

Tighten:
Idle gear shaft bolt to 133 N

⋅m (13.6 kg⋅m / 98 lb⋅ft)

N6A0180E

N6A0181E

N6A0182E

N6A0183E