Isuzu N-Series. Service manual - part 605

6B-6 ENGINE COOLING

• Mixing  ratio

Check the specific gravity of engine coolant in the
cooling system in temperature ranges from 0

° to

50

°C using a suction type hydrometer, then deter-

mine the mixing ratio of the coolant by referring to
the table.

50

5.0

(4.40/5.28)

5.0

(4.40/5.28)

Legend

A. Mixing ratio
B. Specific gravity

C. Coolant temperature

Mixing 

ratio (%)

Specified coolant 

solution:

lit. (imp. qt./U.S. qt)

Water:

lit. (imp. qt/U.S. qt)

N6A3377E

ENGINE COOLING 6B-7

WATER PUMP

Component

Removal

Preparation:

• Disconnect battery ground cable.
• Drain coolant.

1. Fan Shroud

• Remove the reservoir tank hose, bypass hose and

fan guide.

2. Cooling Fan Assembly

• Remove lock nut and take out cooling fan assem-

bly.

3. Power Steering Pump Drive Belt

• Loosen the idler pulley lock nut and loosen adjust

bolt, and remove the drive belt.

4. A/C Compressor Drive Belt

• Loosen A/C compressor idler pulley lock nut and

adjust bolt and remove the drive belt.

Legend

1. Fan shroud

6. Crankshaft damper pulley

2. Cooling fan assembly

7. Timing pulley upper cover

3. Power steering pump drive belt

8. Timing pulley lower cover

4. A/C compressor drive belt

9. Water pump assembly

5. AC generator drive belt

N6A3378E

N6A3380E

6B-8 ENGINE COOLING

5. AC Generator Drive Belt

• Loosen AC Generator mounting bolt (under side)

and adjust plate lock bolt, and remove the drive
belt.

6. Crankshaft Damper Pulley

7. Timing Pulley Upper Cover

8. Timing Pulley Lower Cover
9. Water Pump Assembly

• Remove the O-ring.

Inspection

Make necessary parts replacement if extreme wear or
damage is found during inspection. Should any of the
following problems occur, the entire water pump assem-
bly must be replaced.

• Cracks in the coolant pump body
• Coolant leakage from the seal unit
• Play or abnormal noise in the bearing
• Cracks or corrosion in the impeller

Legend

1. Lock bolt

N6A3379E

N6A3699E

Legend

1. Lower cover
2. Upper cover

N6A3159E

N6A3158E

ENGINE COOLING 6B-9

Installation

1. Water Pump Assembly

• Set O-ring in water pump body groove.

• Install water pump assembly, and tighten to speci-

fied torque.

Tighten:
Pump Fixing Bolt to 20 N

⋅m (2 kg⋅m/14 lb⋅ft)

2. Timing Pulley Lower Cover

• Install timing pulley lower cover, and tighten to

specified torque.

Tighten:
Cover Fixing Bolts to 8 N

⋅m (0.8 kg⋅m/69 lb⋅in)

3. Timing Pulley Upper Cover

• Install timing upper cover, and tighten to specified

torque.

Tighten:
Cover Fixing Bolts to 8 N

⋅m (0.8 kg⋅m/69 lb⋅in)

4. Crankshaft Damper Pulley

• Install crankshaft damper pulley, and tighten to

specified torque.

Tighten:
Pulley Bolt to 19 N

⋅m (1.9 kg⋅m/14 lb⋅in)

4JG2

5. AC Generator Drive Belt
6. A/C Compressor Drive Belt
7. Power Steering Pump Drive Belt

• Install the drive belts and adjust belt.

Check drive belts for wear or damage, and replace
with new ones as necessary. Check belts for ten-
sion, and adjust as necessary.

• Push the middle of belts with a force of 98 N (10 kg/

22 lb) and check each bolt for deflection.

• Standard deflection

N6A3353E

Legend

1. A/C compressor drive belt
2. P/S oil pump drive belt
3. AC generator & cooling fan drive belt

N6A3159E

N6A3297E