1998 ISUZU TROOPER radiator cap

ENGINE COOLING 6B Ð 3
The cooling system is a pressurized coolant forced
circulation type which consists of water pump, thermostat
cooling fan, radiator and other components. The
circulating coolant cools the lubricating oil in the oil filter
and turbocharger.
WATER PUMP
The coolant pump is a centrifugal impeller type and is
driven by V type drive belt.
THERMOSTAT
The thermostat is a wax pellet type with a jiggle valve and
is installed in the thermostat housing.
RADIATOR
The radiator is a tube type with corrugated fins. In order
to raise the boiling point of coolant, the radiator is fitted
with a cap in which the valve is operated under the
pressure.

ENGINE COOLING 6B Ð 9
RADIATOR
REMOVAL
Preparation
·Disconnect battery ground cable.
·Loosen drain plug to drain coolant.
1. Radiator Hose
·Disconnect lower hose and upper hose from the
engine.
2. Fan Guide Lower
·Remove clips on both sides and the bottom lock.
3. Reservoir Tank Hose
·Disconnect the hose from radiator.
4. Bracket
5. Radiator Assembly
·Remove upward the radiator assembly with hose,
taking care not to damage the radiator core by fan
blade.
·Remove cushion rubbers on both sides of the
bottom.
INSPECTION
Radiator Cap
·Measure the valve opening pressure with the radiator
cap tester. Replace the radiator cap if it exceeds the
standard.
Check the condition of negative pressure valve in the
center of valve seat side of the cap. If the valve seat
does not move smoothly due to rust or dust, clean or
replace the radiator cap.
Valve opening pressure
93.3 – 122.7 (0.95 – 1.25/13.5 – 17.8)kPa(Kg/cm2 / psi)

6B Ð 10 ENGINE COOLING
Radiator Core
·Deformed radiator fins could reduce radiation effects,
resulting in overheat. Straighten the fins. In such a
case, take care not to damage the fin roots.
·Remove dust and other foreign materials.
Flushing the Radiator
·Wash the inside of radiator and the coolant passage
with water and neutral detergent. Remove all scales
and rust.
Checking for Coolant Leakage
·Check the cooling system for leakage with the radiator
cap tester by applying 196.0kPa (28.4 psi) air pressure
from filler neck to inside the radiator.
INSTALLATION
5. Radiator Assembly
·Install cushion rubbers on both sides of radiator
bottom.
·Install radiator assembly with hose, taking care not
to damage the radiator core by a fan blade.
4. Bracket
·Support the radiator upper tank with the bracket
and fix the radiator.
3. Reserve Tank Hose
2. Fan Guide, Lower
1. Radiator Hose
·Connect inlet hose and outlet hose to the engine.
·Connect battery ground cable.
·Pour coolant
·Pour coolant up to filler neck of radiator, and up to
MAX mark of reserve tank.
·Start engine to warm up, and check for coolant
level. Replenish coolant if it does not reach the
radiator filler neck, and tighten the cap completely.

6A – 4 ENGINE MECHANICAL
Engine Cooling
Starting System
Cooling system Coolant forced circulation
Radiator (2 tube in row) Tube type corrugated
Heat radiation capacity J/h (kcal/h) 318 x 10
6(76000)
Heat radiation area m
2(ft2) 15.63 (1.454)
Front area m
2(ft2) 0.309 (2.029)
Dry weight N (kg/lb) 83 (8.5/18.7)
Radiator cap
Valve opening pressure kPa (kg/cm
2/ psi) 93.3 – 122.7 (0.95 – 1.25/13.5 – 17.8)
Coolant capacity lit (Imp.qt./US qt.) M/T 2.5 (2.2/2.6) A/T 2.4 (2.1/2.5)
Coolant pump Centrifugal impeller type
Pulley ratio (to 1) 1.2
Coolant total capacity lit (Imp.qt./US qt.) 9.3 (8.2/9.8)
Model HITACHI S14-0
Rating
Voltage V 12
Output kW 2.8
Time sec 30
Number of teeth of pinion 9
Rotating direction (as viewed from pinion) Clockwise
Weight (approx.) N(kg/lb) 49 (5.0/11)
No-load characteristics
Voltage/current V/A 11/160 or less
Speed rpm 4000 or more
Load characteristics
Voltage/current V/A 8.76/300
Torque N·m(kg·m/lb·ft) 7.4 (0.75/5.4) or more
Speed rpm 1700 or more
Locking characteristics
Voltage/current V/A 2.5/1100 or less
Torque N·m(kg·m/lb·ft) 18.6 (1.9/14) or more

6A – 8 ENGINE MECHANICAL
Parts Items Service standard Service limit Remarks
Cylinder
Block—
95.421 – 95.450
(3.7567 – 3.7579)0.20 (0.0079) Warpage
(Upper surface of the cylinder block)
Cylinder bore diameter
Parts Items Service standard Service limit Remarks
Thermostat
Radiator cap83 – 87°C
(181 – 189°F)
More than 9.5 (0.374)
at 100°C (212°F)
88.2 – 117.6 kPa
(12.8 –17.0 psi) Valve opening temperature
Valve full open temperature and lift
Valve opening pressure
Engine Coolingmm (in) mm (in)

ENGINE MECHANICAL 6A – 11
Remove the radiator filler cap only when absolutely
necessary.
Always check the coolant level when the engine is cold.
Always refer to the chart at the left to determine the
correct cooling water to antifreeze solution mixing ratio.
Cooling System Inspection
Install a radiator filler cap tester to the radiator. Apply
testing pressure to the cooling system to check for
leakage.
The testing pressure must not exceed the specified
pressure.
Testing Pressure: 196 kPa (2 kg/cm
2/28.45 psi)
Radiator Cap Inspection
The radiator filler cap is designed to maintain coolant
pressure in the cooling system at 103 kPa (1.05
kg/cm
2/15 psi).
Check the radiator filler cap with a radiator filler cap
tester.The radiator filler cap must be replaced if it fails to hold
the specified pressure during the test procedure.
Radiator Filler Cap Pressure Valve: 88.2 – 117.6 kPa
(0.899 – 1.199 kg/cm
2/12.8 – 17.1 psi)
Negative Valve (Reference): 1.0 – 3.9 kPa
(0.01 – 0.04 kg/cm
2/0.14 – 0.57 psi)
Thermostat Operating Test
1. Completely submerge the thermostat in water.
2. Heat the water.
Stir the water constantly to avoid direct heat being
applied to the thermostat.
3. Check the thermostat initial opening temperature.
Thermostat Initial Opening Temperature:
83 – 87°C (181 – 189°F)
4. Check the thermostat full opening temperature.
Thermostat Full Opening Temperature:
100°C (212°F)
Valve Lift at Fully Open Position: 9.5 mm (0.374
in)0
-10
-20
-30
-40
-50
-60
10 20 30
Mixing ratio (%)
Freezing point ( °C)
40 50 60
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ENGINE COOLING 6B – 3
WATER PUMP
The coolant pump is a centrifugal impeller type and is
driven by V type drive belt.
Legend
(1) Roller Bearing
(2) Ball Bearing
(3) Seal Unit
THERMOSTAT
The thermostat is a wax pellet type with a jiggle valve
and is installed in the thermostat housing.
Legend
(1) Bolt
(2) Thermostat Housing
(3) Thermostat
(4) Intake Manifold
RADIATOR
The radiator is a tube type with corrugated fins. In order
to raise the boiling point of coolant, the radiator is fitted
with a cap in which the valve is operated under the
pressure.
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3 2
PCD 60
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110RS001

ENGINE COOLING 6B – 5
ENGINE COOLANT CHANGE
PROCEDURE
1. To change engine coolant, make sure that the
engine is cool.
WARNING:
When the coolant is heated to a high temperature,
be sure not to loosen or remove the radiator cap.
Otherwise you might get scalded by hot vapor or
boiling water. To open the radiator cap, put a piece
of thick cloth on the cap and loosen the cap slowly
to reduce the pressure once the coolant has
become cooler.
2. Open radiator cap and drain the cooling system by
loosening the drain valve on the radiator and on the
cylinder body.
NOTE: For best results it is suggested that the engine
cooling system be flushed at least once a year. It is
advisable to flush the interior of the cooling system
including the radiator before using anti-freeze
(ethylene-glycol based).
Replace damaged rubber hoses as the engine anti-
freeze coolant is liable to leak out even minor cracks.
Isuzu recommends using Isuzu genuine anti-freeze
(ethylene-glycol based) or equivalent, for the cooling
system and not add any inhibitors or additives.
CAUTION:
A failure to correctly fill the engine cooling system
in changing or topping off coolant may sometimes
cause the coolant to overflow from the filler neck
even before the engine and radiator are completely
full.
If the engine runs under this condition, shortage of
coolant may possibly result in engine overheating.
To avoid such trouble, the following precautions
should be taken in filling the system.
3. To refill engine coolant, pour coolant up to filler neck
using a filling hose which is smaller in outside
diameter than the filler neck. Otherwise air between
the filler neck and the filling hose will block entry,
preventing the system from completely filling up.
4. Keep a filling rate of 9 liter/min. or less. Filling over
this maximum rate may force air inside the engine
and radiator.
And also, the coolant overflow will increase, making
it difficult to determine whether or not the system is
completely full.
5. After filling the system full, pull out the filling hose
and check to see if air trapped in the system is
dislodged and the coolant level goes down. Should
the coolant level go down, repeat topping-off until
there is no more drop in the coolant level.
6. Directly after filling the radiator, fill the reservoir to
the maximum level.
7. Install and tighten radiator cap and start the engine.
After idling for 2 to 3 minutes, stop the engine and
reopen radiator cap. If the water level is lower,
replenish.WARNING:
When the coolant is heated to a high temperature,
be sure not to loosen or remove the radiator cap.
Otherwise you might get scalded by hot vapor or
boiling water. To open the radiator cap, put a piece
of thick cloth on the cap and loosen the cap slowly
to reduce the pressure once the coolant has
become cooler.
8. After tightening radiator cap, warm up the engine at
about 2,000 rpm.
Set heater adjustment to the highest temperature
position, and let the coolant circulate also into
heater water system.
9. Check to see the thermostat has opened by the
needle position of a water thermometer, conduct a
5-minute idle again and stop the engine.
10. When the engine has been cooled, check filler neck
for water level and replenish if required. Should
extreme shortage of coolant be found, check the
coolant system and reservoir tank hose for leakage.
11. Fill the coolant into the reservoir tank up to “MAX”
line.