Isuzu engine C22NE / 22LE / 20LE. Manual - part 28

ENGINE COOLING  6B-5

Diagnosis

Engine Cooling Trouble

Condition

Possible cause

Correction

Engine overheating

Low Engine Coolant level

Replenish

Thermo mater unit faulty

Replace

Faulty thermostat

Replace

Faulty Engine Coolant temperature

sensor

Repair or replace

Clogged radiator

Clean or replace

Faulty radiator cap

Replace

Low engine oil level or use of

improper engine oil

Replenish or change oil

Clogged exhaust system

Clean exhaust system or replace

faulty parts

Faulty Throttle Position sensor

Replace throttle valve assembly

Open or shorted Throttle Position

sensor circuit

Repair or replace

Damaged cylinder head gasket

Replace

Loosen V-belt tension

Adjust belt tension or replace.

Collapsed hoses

Replace

Faulty Fan clutch

Replace

Engine overcooling

Faulty thermostat

Replace

Engine slow to warm-up

Faulty thermostat

Replace

Thermo unit faulty

Replace

6B-6  ENGINE COOLING

Draining and Refilling Cooling
System

Before draining the cooling system, inspect the system and
perform any necessary service to ensure that it is clean, does
not leak and is in proper working order. The engine coolant
(EC) level should be between the "MIN" and "MAX" lines of
reserve tank when the engine is cold. If low, check for leakage
and add EC up to the "MAX" line. There should not be any
excessive deposit of rust or scales around the radiator cap or
radiator filler hole, and the EC should also be free from oil.
Replace the EC if excessively dirty.
1. Completely drain the cooling system by opening the drain

plug at the bottom of the radiator.

2. Remove the radiator cap.
WARNING: TO AVOID THE DANGER OF BEING BURNED,
DO NOT REMOVE THE CAP WHILE THE ENGINE AND
RADIATOR ARE STILL HOT. SCALDING FLUID AND
STEAM CAN BE BLOWN OUT UNDER PRESSURE.
3. Disconnect all hoses from the EC reserve tank.

Scrub and clean the inside of the reserve tank with soap

and water. Flush it well with clean water, then drain it. Install

the reserve tank and hoses.4. Refill the cooling system with

the EC using a solution that is at least 50 percent antifreeze

but no more than 70 percent antifreeze.

4. Refill the cooling system with the EC using a solution that is

at least 50 percent antifreeze but no more than 70 percent

antifreeze.

5. Fill the radiator to the base of the filler neck.

Fill the EC reserve tank to "MAX" line when the engine is

cold.

6. Block the drive wheels and firmly apply the parking brake.

Shift an automatic transmission to "P" (Park) or a manual

transmission to neutral.

7. Remove the radiator cap. Start the engine and warm it up at

2,500 - 3,000 rpm for about 30 minutes.

8. When the air comes out from the radiator filler neck and the

EC level has gone down, replenish with the EC. Repeat this

procedure until the EC level does not go down. Then stop

the engine and install the radiator cap. Let the engine cool

down.

9. After the engine has cooled, replenish with EC up to the

"MAX" line of the reserve tank.

10.Start the engine. With the engine running at 3,000 rpm,

make sure there is no running water sound from the heater

core (behind the center console).

11.If the running water sound is heard, repeat steps 8 to 10.

ENGINE COOLING  6B-7

Water Pump

Water Pump and Associated Parts

Legend

1 Water Pump Assembly

2 O-Ring
3 Bolt

2

3

1

Removal

1. Disconnect battery ground cable.

2. Drain coolant.

3. Radiator hose (on inlet pipe side).

4. Remove timing belt, refer to "Timing Belt" in this manual.

5. Remove water pump assembly.

Inspection

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

•

Crack in the water pump body

•

EC leakage from the seal unit

6B-8  ENGINE COOLING

•

Play or abnormal noise in the bearing

•

Cracks or corrosion in the impeller

Installation

1. Before installing water pump, coat sealing surface with

silicon grease.

2. Install water pump assembly and tighten bolts to the

specified torque.

Torque: 25 N

⋅

m (2.5 kgf.m)

3. Timing belt

•

Install timing belt, refer to timing belt installation step in

"Timing Belt" in this manual.

4. Connect radiator hose and replenish EC.

5. Connect battery ground cable.