Isuzu Trooper (1998-2002 year). Service manual — part 257
ENGINE COOLING
6B–5
Diagnosis
Engine Cooling Trouble
Condition
Possible cause
Correction
Engine overheating
Low Engine Coolant level
Replenish
Incorrect fan installed
Replace
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
Damaged cylinder head gasket
Replace
Engine overcooling
Faulty thermostat
Replace
Engine slow to warm–up
Faulty thermostat
Replace
Thermo unit faulty
Replace
6B–6
ENGINE COOLING
Draining and Refilling Cooling
System
Before draining the cooling system, inspect the system
and perform any necessary service to ensure that it is
clean, does not leak and is in proper working order. The
engine coolant (EC) level should be between the “MIN”
and “MAX” lines of reserve tank when the engine is cold.
If low, check for leakage and add EC up to the “MAX” line.
There should not be any excessive deposit of rust or
scales around the radiator cap or radiator filler hole, and
the EC should also be free from oil.
Replace the EC if excessively dirty.
1. Completely drain the cooling system by opening the
drain plug (2) at the bottom of the radiator.
110RW002
2. Remove the radiator cap.
WARNING: TO AVOID THE DANGER OF BEING
BURNED, DO NOT REMOVE THE CAP WHILE THE
ENGINE AND RADIATOR ARE STILL HOT.
SCALDING FLUID AND STEAM CAN BE BLOWN OUT
UNDER PRESSURE.
3. Disconnect all hoses from the EC reserve tank.
Scrub and clean the inside of the reserve tank with
soap and water. Flush it well with clean water, then
drain it. Install the reserve tank and hoses.
4. Refill the cooling system with the EC using a solution
that is at least 50 percent antifreeze but no more than
70 percent antifreeze.
5. Fill the radiator to the base of the filler neck.
Fill the EC reserve tank to “MAX” line when the engine
is cold.
6. Block the drive wheels and firmly apply the parking
brake. Shift an automatic transmission to “P” (Park)
or a manual transmission to neutral.
7. Remove the radiator cap. Start the engine and warm
it up at 2,500
∼
3,000 rpm for about 30 minutes.
8. When the air comes out from the radiator filler neck
and the EC level has gone down, replenish with the
EC. Repeat this procedure until the EC level does not
go down. Then stop the engine and install the radiator
cap. Let the engine cool down.
9. After the engine has cooled, replenish with EC up to
the “MAX” line of the reserve tank.
10. Start the engine. With the engine running at 3,000
rpm, make sure there is no running water sound from
the heater core (behind the center console).
11. If the running water sound is heard, repeat steps 8 to
10.
ENGINE COOLING
6B–7
Water Pump
Water Pump and Associated Parts
030RS002
Legend
(1) Timing Belt
(2) Idle Pulley
(3) Water Pump Assembly
(4) Gasket
Removal
1. Disconnect battery ground cable.
2. Drain coolant.
3. Radiator hose (on inlet pipe side).
4. Remove timing belt. Refer to “Timing Belt” in this
manual.
5. Remove Idle pulley.
6. Remove water pump assembly.
7. Remove gasket.
Inspection
Make necessary repair and parts replacement if extreme
wear or damage is found during inspection. Should any of
the following problems occur, the entire water pump
assembly must be replaced:
D
Crack in the water pump body
D
EC leakage from the seal unit
D
Play or abnormal noise in the bearing
D
Cracks or corrosion in the impeller.
Installation
1. Install gasket, clean the mating surface of gasket
before installation.
2. Install water pump assembly and tighten bolts to the
specified torque.
Torque: 25 N·m (2.5 Kg·m/18 lb ft)
D
Tightening order
The tightening order are in the illustrate.
NOTE: To prevent the oil leakage, apply the LOCTITE
262 or an equivalent, to the arrow marked fixing bolt
thread.
030RW008
6B–8
ENGINE COOLING
3. Idle pulley
D
Install idle pulley and tighten bolt to the specified
torque.
Torque: 52 N·m (5.3 Kg·m/38 lb ft)
4. Timing belt
D
Install timing belt. Refer to timing belt installation
step in “Timing Belt” in this manual.
5. Connect radiator inlet hose and replenish EC.
6. Connect battery ground cable.
Thermostat
Thermostat and Associated Parts
031RW001
Legend
(1) Thermostat Housing
(2) Thermostat
(3) Outlet Pipe
Removal
1. Disconnect battery ground cable.
2. Drain engine coolant from the radiator and engine.
3. Disconnect radiator hose from the inlet pipe.
4. Remove thermostat housing.
5. Remove thermostat(2).
Inspection
Suspend the thermostat in a water–filled container using
thin wire. Place a thermometer next to the thermostat.
Do not directly heat the thermostat.
Gradually increase the water temperature. Stir the water
so that the entire water is same temperature.
031RS003
Confirm the temperature when the valve first begins to
open.
Valve opening temperature 74.5C
∼
78.5
°
C
(166.1
°
F
∼
173.3
°
F)
Confirm the temperature when the valve is fully opened.
Valve full open temperature and lift More than
8.5mm (0.33 in) at 90
°
C (194
°
F)
Make necessary repair and parts replacement if extreme
wear or damage is found during inspection.
Installation
1. Install thermostat into the outlet pipe(4) making sure
that the air hole is in the up position.
2. Install thermostat housing and tighten bolts to the
specified torque.
Torque: 25 N·m (2.5 Kg·m/18 lb ft)
3. Installation rubber hose.
4. Replenish engine coolant (EC).
5. Start engine and check for EC leakage.
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