Isuzu KB P190. 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