Isuzu KB P190. Manual - part 381

ENGINE COOLING (4JK1/4JJ1)  6B-1 

SECTION 6B 

ENGINE COOLING 

TABLE OF CONTENTS 

 

Main Data and Specifications.............................  6B-2

General Description............................................  6B-3

Coolant Flow ...................................................  6B-3

Water Pump ....................................................  6B-4

Thermostat ...................................................... 6B-4

Radiator........................................................... 6B-5

Antifreeze Solution ..........................................  6B-5

Diagnosis............................................................ 6B-6

Draining and Refilling Cooling System ...............  6B-7

Water Pump .......................................................  6B-8

Removal .......................................................... 6B-8

Inspection and Repair .....................................  6B-9

Installation ....................................................... 6B-9

Thermostat ......................................................... 6B-11

Removal .......................................................... 6B-11

Inspection and Repair ..................................... 6B-11

Operating Test of Thermostat ......................... 6B-11

Installation ....................................................... 6B-12

 

 

Radiator.............................................................. 6B-13

Radiator and Associated Parts........................ 6B-13

Removal .......................................................... 6B-14

Inspection and Repair ..................................... 6B-15

Radiator Cap ................................................... 6B-15

Radiator Core.................................................. 6B-15

Flushing the Radiator ...................................... 6B-15

Cooling System Leakage Check ..................... 6B-15

Installation ....................................................... 6B-16

Engine Coolant Change .................................. 6B-16

Fan Clutch with Cooling Fan .............................. 6B-17

Inspection and Repair ..................................... 6B-17

Special Tools................................................... 6B-18

6B-2  ENGINE COOLING (4JK1/4JJ1) 

Main Data and Specifications 

Description 

Item 

M/T A/T 

Cooling system 

Water pump type 

  Pump to crankshaft speed ratio 

(To 1) 

  Delivery volume 

lit (US/UK gal)/min 

   

Pump speed at 5600 rpm 

   

Water temperature at 30

°C (86°F) 

  Pump bearing type 

 

Thermostat type 

  Valve initial opening temperature 

°C (°F) 

  Valve full opening temperature 

°C (°F) 

  Valve lift at fully open position 

mm (in) 

Engine coolant forced circulation 

Centrifugal impeller type 

1.25 

240 (63.1/53.3) 

 

 

Double row shaft 

 

Wax pellet with jiggle valve 

85 (185) 

100 (212) 

10 (0.39) 

Radiator 

Tube type corrugated 

  Heat radiation capacity 

kW (kcal/h) 

93 (80.2) 

  Heat radiation area 

m

2

 (ft

2

) 11.63 

(125.2) 

  Radiator front area 

m

2

 (ft

2

) 0.28 

(3) 

  Radiator dry weight 

N (kg/lb) 

52 

53 

  Radiator cap valve opening pressure kPa (kg/cm

2

/psi) 

93.3 - 122.7 (0.95 - 1.25/13.5 - 17.8) 

  Engine coolant capacity 

lit (U.S pint) 

4.0 (8.5) 

4.0 (8.5) 

  Engine coolant total capacity 

lit (U.S pint) 

8.7 (18.4) 

8.6 (18.2) 

 

ENGINE COOLING (4JK1/4JJ1)  6B-3 

General Description 

Coolant Flow 

 

 
 
 
 

 

 
 

 

 

RTW76BLF000301 

 

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 pipe
and back to the cylinder body.  

The coolant does not circulate through the radiator. 

When the coolant temperature reaches the 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 the specified value. All of the
coolant is now circulating through the radiator for
effective engine cooling. 

 

6B-4  ENGINE COOLING (4JK1/4JJ1) 

Water Pump 

  

 

 

 

RTW56BSF000101 

A centrifugal type water pump forcefully circulates the
coolant through the cooling system. 

 

 

The water pump is not a disassembled type. 

Thermostat 

  

 
 

 

 

RTW56BSF000201 

A wax pellet type thermostat is used.