LEXUS SC400 1991 Service Repair Manual

THERMOSTAT
HINT: Removing the thermostat would decrease the cooling
efficiency. Do not remove the thermostat, even if it tends to
overheat.
COMPONENTS
REMOVAL OF THERMOSTAT
1. DRAIN ENGINE COOLANT (See page CO±5)
2. REMOVE THERMOSTAT (a) Remove the two nuts holding the water inlet to the water
pump, and disconnect the water inlet from the water
pump.
(b) Remove the thermostat.
(c) Remove the gasket from the thermostat.
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COOLING SYSTEM Thermostat
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INSPECTION OF THERMOSTAT
INSPECT THERMOSTATHINT: The thermostat is numbered with the valve opening
temperature.
(a) Immerse the thermostat in water and gradually heat thewater.
(b) Check the valve opening temperature.
Valve opening temperature: 80±84 5C (176±183 5F)
If the valve opening temperature is not as specified, replace
the thermostat.
(c) Check the valve lift.
Valve lift:
8.5 mm (0.335 in.) or more at 95 5C (203 5F)
If the valve lift is less than specification, replace the thermo-
stat.
(d) Check that the valve spring is tight when the thermostat
is fully closed.
If not closed, replace the thermostat.
INSTALLATION OF THERMOSTAT
(See Components on page CO±10)
1. PLACE THERMOSTAT IN WATER INLET (a) Install a new gasket to the thermostat.
(b) A l i g n t h e j i g g l e v a l v e o f t h e t h e r m o s t a t w i t h t h eprotrusion, and insert the thermostat in the water inlet.
HINT: The jiggle valve may be set within 10 5 of either side of
the prescribed position.
2. INSTALL WATER INLET Install the water inlet with the two nuts.
Torque: 8.8 N Vm (90 kgf Vcm, 78 in. Vlbf)
3. FILL WITH ENGINE COOLANT (See page CO±6)
Capacity (w/ Heater):
M/T 8.5 liters (9.0 US qts, 7.5 Imp. qts)
A/T 8.4 liters (8.9 US qts, 7.4 Imp. qts)
4. START ENGINE AND CHECK FOR LEAKS
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COOLING SYSTEM ThermostatCO±11
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THERMOSTAT
HINT: Removal of the thermostat would have an adverse ef-
fect, causing a lowering of cooling efficiency. Do not remove
the thermostat, even if the tends to overheat.
COMPONENTS FOR REMOVAL AND
INSTALLATION
REMOVAL OF THERMOSTAT
1. DRAIN ENGINE COOLANT (See page CO±6)
2. REMOVE THERMOSTAT (a) Remove the two nuts holding the water inlet to the inlethousing, and disconnect the water inlet from the inlet
housing.
(b) Remove the thermostat.
(c) Remove the gasket from the thermostat.
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COOLIING SYSTEM Thermostat
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INSPECTION OF THERMOSTAT
INSPECT THERMOSTATHINT: The thermostat is numbered with the valve opening
temperature.
(a) Immerse the thermostat in water and gradually heat thewater.
(b) Check the valve opening temperature.
Valve opening temperature: 80±84 5C (176±183 5F)
If the valve opening temperature is not as specified, replace
the thermostat.
(c) Check the valve lift.
Valve lift:
10 mm (0.39 in.) or more at 95 5C (203 5F)
If the valve lift is less than specification, replace the thermo-
stat.
(d) Check that the valve spring is tight when the thermostat
is fully closed.
If necessary, replace the thermostat.
INSTALLATION OF THERMOSTAT
(See Components on page CO±12)
1. PLACE THERMOSTAT IN WATER INLET HOUSING (a) Install a new gasket to the thermostat.
(b) Insert the thermostat into the water inlet housing withthe jiggle valve facing straight upward.
HINT: The jiggle valve may be set within 30 5 of either side of
the prescribed position.
2. INSTALL WATER INLET Install the water inlet with the two nuts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
3. FILL WITH ENGINE COOLANT (See page CO±7)
4. START ENGINE AND CHECK FOR LEAKS
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COOLIING SYSTEM ThermostatCO±13
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RADIATOR
CLEANING OF RADIATOR
Using water or a steam cleaner, remove any mud and dirt
from the radiator core.
NOTICE: If using a high pressure type cleaner, be careful
not to deform the fins of the radiator core. If the cleaner
nozzle pressure is 2,942±3,432 kPa (30±35 kgf/cm2,
427±498 psi), keep a distance at least 40±50 cm
(15.75±19.69 in.) between the radiator core and cleaner
nozzle.
INSPECTION OF RADIATOR
1. REMOVE RADIATOR CAP FROM RESERVOIR TANK
2. INSPECT RADIATOR CAPUsing a radiator cap tester, pump the tester and measure the
relief valve opening pressure.
Standard opening pressure:
74±103 kPa
(0.75±1.05 kgf/cm, 10.7±14.9 psi)
Minimum opening pressure:
59 kPa (0.6 kgf/cm, 8.5 psi)
If the opening pressure is less than minimum, replace the ra-
diator cap.
3. INSPECT COOLING SYSTEM FOR LEAKS (a) Fill the radiator with coolant and attach a radiator captester to the reservoir tank.
(b) Warm up the engine.
(c) Pump it to 118 kPa (1.2 kgf/cm2, 17.1 psi), check that pressure does not drop.
If the pressure drops, check for leaks as the hoses, radiator
or water pump. If no external leaks are found, check the heat-
er core, cylinder block and head.
4. REINSTALL RADIATOR CAP
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COOLIING SYSTEM Radiator
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COMPONENTS FOR REMOVAL AND
INSTALLATION
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COOLIING SYSTEM RadiatorCO±15
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REMOVAL OF RADIATOR
(See Components on page CO±15)
1. REMOVE BATTERY CAUTION: Work must be started after approx. 20 seconds or
longer from the time the ignition switch is turned to the
ºLOCKº position and the negative (±) terminal cable is dis-
connected from the battery.
2. REMOVE ENGINE UNDER COVERS
3. DRAIN ENGINE COOLANT (See page CO±6)
4. REMOVE RADIATOR RESERVOIR TANK (a) Disconnect the coolant level sensor connector.
(b) Disconnect the following hoses:(1) Reservoir hose from water inlet housing
(2) Reservoir hose from radiator
(c) Remove the two bolts and reservoir tank bracket.
(d) Disconnect the reservoir tank from the reservoir tank bracket, and remove the reservoir tank.
5. DISCONNECT HOSES Disconnect the following hoses:(1) Upper radiator hose from radiator
(2) Lower radiator hose from radiator
(3) Two oil cooler hoses (for A/T) from radiator. Plug hose end.
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COOLIING SYSTEM Radiator
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(4) Pressure hose from hydraulic motor
(5) Return hose from hydraulic motor
6. DISCONNECT COOLING FAN INLET PIPE FROM FAN SHROULD
Remove the two bolts, brackets and bushings, and discon-
nect the inlet pipe.
7. DISCONNECT COOLING FAN RESERVOIR TANK FROM FAN SHROULD
(a) Disconnect the suction hose from the clamp on the fanshrould.
(b) Remove the four bolts, and disconnect the reservoir tank.
8. DISCONNECT WATER TEMPERATURE SENSOR CONNECTOR
(a) Disconnect the water temperature sensor connector.
(b) Disconnect the wire cl amp from the radiator fan shrould.
9. REMOVE RADIATOR (a) Re mo ve th e two bo lts, scre w an d u pper radiator
support. Remove the two upper radiator supports.
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(b) Slightly lift the radiator, and disconnect the two oil cooler
hoses (for cooling fan) from the hose clamp on the
radiator fan shrould.
(c) Remove the radiator.
(d) Remove the two lower radiator supports.
10. REMOVE FAN SHROULD FROM RADIATOR Remove the four bolts and fan shrould.
INSTALLATION OF RADIATOR
(See Components on page CO±15)
1. INSTALL FAN SHROULD TO RADIATOR Install the fan shrould with the four bolts.
Torque: 4.9 N Vm (50 kgf Vcm, 43 in. Vlbf)
2. INSTALL RADIATOR
(a) Install the two lower radiator supports to the radiator.
(b) Place the radiator on the body bracket.
(c) Slightly lift the radiator, and connect the two oil coolerhoses (for cooling fan) to the hose clamp on the radiator
fan shrould.
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COOLIING SYSTEM Radiator
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(d) Install the upper radiator support with the two bolts andscrew. Install the two upper radiator supports.
Torque: 12 N Vm (120 kgf Vcm, 9 ft Vlbf)
3. CONNECT WATER TEMPERATURE SENSOR
CONNECTOR
(a) Connect the water temperature sensor connector.
(b) Install the wire clamp to the radiator fan shrould.
4. INSTALL COOLING FAN RESERVOIR TANK TO FAN SHROULD
(a) Install the reservoir tank with the four bolts.
Torque: 4.9 N Vm (50 kgf Vcm, 43 in. Vlbf)
(b) Install the suction hose to the clamp on the fan shrould.
5. INSTALL COOLING FAN INLET PIPE TO FAN SHROULD Install the inlet pipe with the two bushings, brackets and
bolts.
Torque: 4.9 N Vm (50 kgf Vcm, 43 in. Vlbf)
6. CONNECT HOSES
Connect the following hoses:(1) Pressure hose to hydraulic motor Connect the pres-
sure hose with a new gasket and union bolt.
Torque: 64 N Vm (650 kgf Vcm, 47 ft Vlbf)
(2) Return hose to hydraulic motor
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