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

110RS001

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)

F06RW005

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.

PTW46BSH000201

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