Isuzu KB P190. Manual - part 237

6B – 4  ENGINE COOLING 

 

GENERAL DESCRIPTION 

COOLANT FLOW 

 

 
 
 
 
 
 

 

 

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The engine cooling system consists of the radiator, the water pump, the cooling fan, and the thermostat. 
To quickly increase cold engine coolant temperature for smooth engine operation, the coolant is circulated by the 
water pump and thermostat through the bypass hose and back to the cylinder body. 

 

The coolant does not circulate through the radiator. 
When the coolant temperature reaches specified value, the thermostat will begin to open and a gradually increasing 
amount of coolant will circulate through the radiator. 
The thermostat will be fully open when the coolant temperature reaches specified value. All of the coolant is now 
circulating through the radiator for effective engine cooling. 
 

ENGINE COOLING   6B – 5 

 

WATER PUMP 

 

 

 

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A centrifugal type water pump forcefully circulates the coolant through the cooling system. 
The water pump is not disassembled type. 
 

THERMOSTAT 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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A wax pellet type thermostat is used. 

The jiggle valve accelerates engine warm-up. 

 

6B – 6  ENGINE COOLING 

 

  

 

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RADIATOR 

The radiator is a tube type with corrugated fins. In order to
raise the boiling point of the coolant, the radiator is fitted with a

cap in which the valve is operated at 93.3 

∼

 122.7 kPa (13.5 

∼

17.8 psi) pressure. (No oil cooler provided for M/T) 
 

 

 
 

 

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Antifreeze Solution 

NOTE: Antifreeze solution + Water = Total cooling system
capacity. 

Total Cooling System Capacity Lit (US / UK gal) 

9.4 (2.5/21) 4JA1L/TC 

M/T 10.1 (2.7/2.2) 4JH1TC 

A/T 10.0 (2.6/2.2) 4JH1TC 

See section 0B MAINTENACE AND LUBRICATION. 
 

 

  

 

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 NOTE: 

To maintain the corrosion resistance of the aluminum 
radiator, water and antifreeze must be combined in a 1:1 
solution (50% antifreeze and 50% water) 

 

 

 

ENGINE COOLING   6B – 7 

DIAGNOSIS 

Engine Cooling Trouble 

 

Symptom Possible 

Cause  Action 

Low Engine Coolant level 

Replenish 

Thermo meter 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 

Engine overheating 

Damaged cylinder head gasket 

Replace 

Engine overcooling 

Faulty thermostat 

Replace 

Faulty thermostat 

Replace 

Engine slow to warm–up 

Thermo unit faulty 

Replace