Isuzu KB P190. Service manual — part 799

Engine Cooling – V6 Engine

Page 6B1–61

4

Engine Cooling System
Diagnosis

4.1

Poor Heater Operation

Little or no heat coming from the heater, especially at idle could be an indication of a cooling system problem.

As the coolant level begins to get lower than normal, air enters the system to replace the missing coolant. The heater
core is one of the highest parts of the cooling system and therefore, the first area to lose coolant circulation.

At first, with a small amount of coolant loss, lack of heat will be most noticeable at idle. As driving speed increases, the
engine pumps more coolant and more heat is now able to pass through the heater core.

If coolant level drops even lower, heater operation will become less effective, even during normal driving. Cooling and
engine systems can be adversely affected if problem is not corrected before overheating occurs.

4.2

Leaking Cylinder Head Gasket

Combustion gases leaking past the cylinder head gasket can pressurise the cooling system, forcing coolant out of the
system and into the coolant recovery reservoir.

Indications are air bubbles in the coolant or an overflow condition of the recovery reservoir.

4.3

Question the Customer

To avoid needless time and cost in diagnosing cooling system complaints, the customer should be questioned about
driving conditions that place abnormal loads on the cooling system.

1

Is overheating occurring after prolonged idle, in gear, with air conditioning system operating?

If answer is YES – instruct owner on driving techniques that would avoid overheating such as:

•

Idle in neutral as much as possible – increase engine rpm to get higher air flow (due to an increase in voltage
to the fan) and coolant flow through the radiator

•

Turn air conditioning system off during extended idling periods if overheating is indicated on temperature
gauge. Further diagnostic checks should not be required

2

Is overheating occurring after prolonged driving in slow city traffic, traffic jams, parades, etc?

If answer is YES, explain driving technique to the customer, that would avoid overheating – same as for prolonged
idle – No.1. Further diagnostic checks should not be required.

4.4 Diagnostic

Chart

If none of the above conditions apply, refer to the following Diagnosis Chart.

To effectively use this chart, question the customer to determine which of the following three categories apply to the
complaint:

1

If complaint is hot indication on temperature gauge.

Was temperature reading accompanied by boiling?

•

If answer is YES, go to overheating on diagnosis chart

•

If answer is NO, check temperature gauge and sender

2

If complaint is boiling – go to overheating on diagnosis chart.

3

If complaint is coolant loss. Determine if customer is filling the system correctly.

4

If incorrect filling is not the problem, go to coolant loss in the diagnosis chart.

Engine Cooling – V6 Engine

Page 6B1–62

Refer to 3.1 Service Notes in this Section, for
important safety items before removing the
coolant filler pressure cap or servicing the
system.

The cooling system is designed to operate at
120 –

––

– 130 kPa and a maximum temperature

not above 130

°°°°C.

Cooling System Diagnosis

Step Action

Result

Yes

No

1

Check Temperature gauge reading

High Temp.

Low Temp.

Go to Step 2

Go to Step 6

–

2

Check drive belt condition and tension. Refer to 6A1
Engine Mechanical.

To Specification

Go to Step 3

Replace drive

belt or

tensioner.

3

Check coolant

Boiling

Go to Step 4

Go to Step 5

4

Check coolant level. Refer to 3.2

Coolant

Maintenance in this Section.

Low

Go to Step 10

Go to Step 6

5

Check coolant filler cap. Refer to 3.7

Pressure

Testing – Coolant Filler Cap Pressure Testing in this
Section

OK?

Go to Step 8

Replace

Coolant filler

cap

6

Check thermostat. Refer to 3.8 Thermostat in this
Section.

OK?

Go to Step 9

Go to Step 13

7

Check Engine Coolant Temperature (ECT) sensor.
Refer to 6C1 Engine Management General Information.

Faulty

Replace

Go to Step 12

8

Check cooling fan operation. Refer to 6C1 Engine
Management General Information.

Operational

Go to Step 10

Repair

9

Check for collapsed upper or lower radiator hose.

Collapsed

Replace

Go to Step 13

10

Visual system check

Leaks

Go to Step 13

Go to Step 11

11

Check coolant concentration. Refer to 3.2

Coolant

Maintenance.

To Specification

Go to Step 12

Correct

Concentration

Level

12

Check radiator core for bent fins, dirt, bugs or other
obstructions.

Obstructed

Clean or

straighten

Go to Step 14

13

Pressure Test cooling system. Refer to 3.7 Pressure
Testing in this Section.

Leaks Repair

System

OK

14

If none of the above require repair, the problem is
complex or of a major nature.

Refer to 4.5 Problems Not Requiring Disassembly of
Cooling System or 4.6 Problems Requiring Disassembly
of Cooling System.

– –

–

Engine Cooling – V6 Engine

Page 6B1–63

4.5

Problems Not Requiring Disassembly of
Cooling System

1

Large obstructions blocking radiator or condenser airflow.

•

Auxiliary oil coolers

•

License plate

•

Obstruction of radiator grille, for example, driving lights or mud

2

Loose, damaged or missing air chute side panels.

3

Missing or damaged air baffle.

4

Cracked or loose coolant recovery system hose.

5

Leaking heater component such as the heater core or water valve.

4.6

Problems Requiring Disassembly of
Cooling System

1

Damaged cooling fan or faulty motor operation.

2

Pressure test cooling system.

3

Defective coolant pump.

•

Eroded or broken impeller vanes

•

Failed bearing or seal – check for shaft or bearing end play

4

Internally blocked radiator core.

5

Obstruction of coolant recovery system.

6

Internal system leaks.

•

Head gaskets

•

Cracked cylinder block

•

Engine front cover

•

Intake manifold gaskets

7

Blocked coolant passages in cylinder heads or block – remove cylinder heads and check.

4.7

Black Light and Dye Leak Diagnosis
Method

It is strongly recommended that this diagnostic method be used to diagnose fluid leaks. This method is a proven and
reliable method that identifies the specific leak source.

The black light kit can be used for the leak detection of a number of fluids, when used with the appropriate tracer dye.

Examples are: Coolant, Engine Oil, Automatic Transmission Fluid and Air Conditioning Refrigerant (R134A).

The following is a summary of the steps involved in detecting a cooling system fluid leak using black light and dye:

1

Pour specified amount of dye into the cooling system via the coolant filler cap on the outlet housing. Refer 3.1

Service Notes in this Section.

2

Road test the vehicle under normal operating conditions.

3

Direct the light towards the suspect area. The fluid leak will appear as a brightly coloured path leading from the
source.

4

Repair fluid leak and recheck to ensure that leak has been rectified.

5

Refer to the manufacturer’s directions when using this method.

Engine Cooling – V6 Engine

Page 6B1–64

5 Specifications

G e n e r a l

Coolant Filler Cap Pressure Rating . . . . . . . . . . . . . . . . . . . .120 kPa

Cooling System Capacity

Automatic Transmission. . . . . . . . . . . . . . . . . . . . . . 9.9 litres

Manual Transmission . . . . . . . . . . . . . . . . . . . . . . .. 10.3 litres

Coolant Corrosion Inhibitor Quantity When Refilling System

Automatic Transmission Models. . . . . . . . . . . . . . . . . . . 5 litres

Manual Transmission Models. . . . . . . . . . . . . . . . . . .. 5.2 litres

N O T E

DEX-COOL® long life coolant or equivalent such
as Extended Life Anti-freeze Coolant, conforming
to GM Specification 6277M, must be used when
changing coolant.

T h e r m o s t a t

Type. . . . . . . . . . . . . . . . . . . . . . . ...Power element (wax pellet)

Start to Open at . . . . . . . . . . . . . . . . . . . . . . . . . . .82 ± 2° C

Fully Open at . . . . . . . . . . . . . . . . . . . . . . . . . . .. 95° C max.

C o o l a n t P u m p

Type. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Centrifugal

Drive . . . . . . . . . . . . . . . . . . . . . . . . Multi-Vee Serpentine Belt

Bearing Type . . . . . . . . . . . . . . . . . . . . . Double Row Ball Bearing

R a d i a t o r

Core type . . . . . . . . . . . . . . . . . . . . . . . Aluminium crossflow core

Overall width . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664 mm

Core width. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 510 mm

Overall height. . . . . . . . . . . . . . . . . . . . . . . . . . . ...602 mm

Core height . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..512 mm

Core thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . ...27 mm

Plastic Tanks . . . . . . . . . . . . . . . . . . . .. Nylon 6.6 (30% Glass Filled)

R a d i a t o r H o s e s

L o w e r

U p p e r

Number. . . . . . . . . . . . . . . . . . . ...One. . . . . . . . One

Type. . . . . . . . . . . . . . . . . . . . Moulded . . . . . ..Moulded

Inside diameter . . . . . . . . . . . . . . . . .34 mm . . . . . . 34 mm