1991 LEXUS SC300 radiator cap

16. INSTALL EXHAUST MANIFOLD(a) Install a new gasket and the exhaust manifold with thefour nuts. Install the No. 1 and No. 2 exhaust manifolds.
Torque: 39 N Vm (400 kgf Vcm, 29 ft Vlbf)
(b) Install the manifold heat insulator with the four nuts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
(c) Connect the two oxygen sensor connectors.
17. INSTALL NO. 2 FRONT EXHAUST PIPE (See step 5 on page EM±105)
18. INSTALL TIMING BELT (See steps 8 to 14 on pages EM±30 to 33)
19. INSTALL RADIATOR AND WATER PUMP PULLEY (See steps 15, 16, 19 and 24 on pages EM±110 to 112)
20. INSTALL SPARK PLUGS (See step 6 on page IG±9)
Torque: 18 N Vm (180 kgf Vcm, 13 ft Vlbf)
21. CONNECT HIGH±TENSION CORDS TO SPARK PLUGS
(See steps 14 to 21 on pages EM±17 to 21)
22. FILL ENGINE WITH COOLANT (See page CO±5)
Capacity (w/ Heater): M/T 8.5 liters (9.0 US qts, 7.5 lmp. qts)
A/T 8.4 liters (8.9 US pts, 7.4 lmp. qts)
23. START ENGINE AND CHECK FOR LEAKS
24. (A/T)CHECK AUTOMATIC TRANSMISSION FLUID LEVEL
(See page MA±11)
NOTICE: Do not overfill.
25. CHECK IGNITION TIMING (See page IG±14)
Ignition timing: 105 BTDC @ idle
(w/ Terminals TE1 and E1 connected)
26. PERFORM ROAD TEST Check for abnormal noise, shock, slippage, correct shift
points and smooth operation.
27. RECHECK ENGINE COOLANT LEVEL
±
ENGINE MECHANICAL Cylinder HeadEM±61
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ENGINE TUNE±UP
INSPECTION OF ENGINE COOLANT
1. INSPECT ENGINE COOLANT LEVEL AT RESERVOIRTANK
The coolant level should be above the ºCOLD LEVELº at
normal temperature (20 5C (68 5F)).
If low, check for leaks and add coolant up to the ºCOLD
LEVELº.
2. INSPECT ENGINE COOLANT QUALITY There should be any excessive deposits of rust or scales
around the radiator cap or reservoir tank filler hole, and the
coolant should be free from oil.
If excessively dirty, clean the coolant passages and replace
the coolant.
INSPECTION OF ENGINE OIL
1. INSPECT ENGINE OIL QUALITYCheck the oil for deterioration, entry of water, discoloring or
thinning.
If the quality is poor, replace the oil.
Oil grade: API grade SG, Energy±Conserving II multigrade.
Recommended viscosity is as shown, with SAE
5W±30 being the preferred engine oil.
Drain and refill oil capacity: w/ oil filter change4.8 liter (5.1 US qts, 4.2 lmp. qts)
w/o oil filter change 4.5 liter (4.8 US qts, 4.0 lmp. qts)
2. INSPECT ENGINE OIL LEVEL The oil level should be between the ºLº and ºFº marks on the
dipstick.
If low, check for leakage and add oil up to ºFº mark.
EM±8
±
ENGINE MECHANICAL Engine Tune±Up
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Coolant which is heated in the water jacket is pumped to the radiator, through which a cooling fan blows
air to cool the coolant as it passes through. Coolant which has been coo\
led is then sent back to the engine by
the water pump, where it cools the engine. The water jacket is a network of channels in the shell of the cylinder bloc\
k and cylinderhead through which
coolant passes. It is designed to provide adequate cooling through the cylinders and combus\
tion chambers
which become heated during engine operation.
RADIATOR The radiator performs the function of cooling the coolant which has pass\
ed through the waterjacket and
become hot, and it is mounted in the front of the vehicle. The radiator consis\
ts of an upper tank and lower tank,
and a core which connects the two tanks. The upper tank contains the inlet \
for coolant from the water jacket
and the filler inlet. It also has a hose attached through which excess cool\
ant or steam can flow. The lower tank
contains the outlet for coolant and drain plug. The core contains many t\
ubes through which coolant flows from
the upper tank to the lower tank as well as cooling fins which radiate heat\
away from the coolant in the tubes.
The air sucked through the radiator by the cooling fan, as well as the wind generated by the ve\
hicle's travel,
passes through the radiator, cooling the coolant. Models with automatic transmission include an aut\
omatic
transmission fluid cooler built into the lower tank of the radiator. A cooling fan is mounted behind radiator to assist
the flow of air through the radiator. When the coolant temperature is low, the fan operates slowly to help the warm
up, and when the coolant temperature becomes high, the fan speed is increas\
ed to provide the air flow required
for cooling.
RADIATOR CAP (on Reservoir Tank)
The radiator cap is a pressure type cap which seals the radiator, resulting in pressurization of the radiator
as the coolant expands. The pressurization prevents the coolant from boi\
ling even when the coolant tempera-
ture exceeds 100 5C (212 5F). A relief valve (pressurization valve) and a vacuum valve (negati\
ve pressure valve)
are built into the radiator cap. The relief valve opens and lets steam esca\
pe through the overflow pipe when
the pressure generated inside the cooling system exceeds the limit (coolant temperature: 110±120 5C
(230±248 5F) pressure; 29.4±98.1 kPa (0.3±1.0 kgf/cm2, 4.3±14.2 psi)). The vacuum v\
alve opens to alleviate
the vacuum which develops in the coolant system after the engine is stopped\
and the coolant temperature
drops.
RESERVOIR TANK The purpose of the reservoir tank is to catch coolant overflows created by \
volumetrix expansion when the
coolant temperature increases. The cap of the reservoir tank is a pressure type\
which prevents deterioration
of the LLC (Long Life Coolant) caused by contact with atmospheric air, increases vaporization performance and
reduces loss of the coolant volume.
WATER PUMP The water pump is mounted on the front of the cylinder block and driven by t\
he reverse side of the timing
belt.
THERMOSTAT The thermostat has a wax type by±pass valve and is mounted in the wat\
er inlet housing. The thermostat
begins to open at the temperature of 80 5C (180 5F). When the coolant temperature is low, the valve closes to
prevent coolant flow to the radiator, thus permitting the engine to warm up rapidly. When the by±pass valve
opens the by±pass circuit, the engine coolant continues to circulate \
inside the engine, quickly and uniformly
warming up to the appropriate temperature. When the coolant temperature is high\
, the valve opens and coolant
flows to the radiator where it is cooled. When the wax inside the thermostat \
is heated, it expands and thus
creates pressure which overpowers the force of the spring which keeps the valve\
closed. When the wax cools,
its contraction causes the force of the spring to take effect once more, closing the valve.
ELECTRONICALLY CONTROLLED HYDRAULIC COOLING FAN (See page CO±22)
±
COOLIING SYSTEM DescriptionCO±3
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EQUIPMENT
 Part Name\
 \
Note
 Caliper gauge\
 \
Hydraulic pump, Hydraulic motor
 Micrometer\
 \
Hydraulic pump, Hydraulic motor
 Precision straight edge\
 \
Hydraulic pump, Hydraulic motor Pressure gauge\
 \

 
Radiator cap tester\
 
\
 

Thermometer
\
 
\

\

 Torque wrench\
 \

 Vernier caliper\
 \
Hydraulic pump
COOLANT 

Item
 

Capacity
 

Classification
 
Item
 Liters US qts lmp. qts 
Classification
 Engine coolant 10.8 11.4 9.5 Ethylene±glycol base
LUBRICANT
 Item Capacity Classification
 Cooling fan fluid ± ATF DEXRON
[II
SSM (SPECIAL SERVICE MATERIALS) 

Part Name
 

Part No.
\
 

\
Use etc.
 


Seal packing 1282B,
Three bond 1282B or equivalent 


08826±00100\
 

\

Water pump, Water inlet housing
±
COOLIING SYSTEM PreparationCO±5
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CHECK AND REPLACEMENT OF
ENGINE COOLANT
1. CHECK ENGINE COOLANT LEVEL AT RESERVE TANKThe coolant level should be above the ºCOLD LEVELº at nor-
mal temperature (20 5C (68 5F)).
If low, check for leaks and add coolant up to the ºCOLD LEV-
ELº.
2. CHECK ENGINE COOLANT QUALITY There should not be any excessive deposits of rust or scales
around the radiator cap or reservoir tank filler hole, and the
coolant should be free from oil.
If excessively dirty, clean the coolant passages and replace
the coolant.
3. REPLACE ENGINE COOLANT (a) Remove the radiator cap from the reservoir tank.
CAUTION: To avoid the danger of being burned, do not
remove the cap while the engine and radiator are still hot,
as fluid and steam can be blown out under pressure.
(b) Remove the filler plug from the water inlet housing.
(c) Loosen the three drain plugs on the radiator and
cylinder block, drain the coolant from the radiator and
engine.
(d) Clean the coolant passages.
(e) Close the three drain plugs.
Torque (Engine drain plug):
18 NVm (180 kgf Vcm, 13 ft Vlbf)
CO±6±
COOLIING SYSTEM Check and Replacement of Engine Coolant
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(f) Slowly add coolant to water inlet housing until it is full.w Use a good brand of ethylene±glycol base coolant,
mixed according to the manufacturer's directions.
w Using coolant which includes more than 50%
ethylene±glycol (but not more 70%) than is
recommended.
NOTICE:
w Do not use alcohol type coolant.
w The coolant should be mixed with demineralized water or
distilled water.
Capacity (w/ Heater): 10.8 liters (11.4 US qts, 9.5 lmp. qts)
(g) Reinstall a new gasket and filler plug to the water inlethousing.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
(h) Slowly add coolant to reservoir tank until it is full.
(i) Reinstall the radiator cap.
(j) Bleed the cooling system.
w Start the engine, and open the heater water valve.
w Maintain the engine speed at 2,000 rpm, and warm
up the engine.
(k) Check for leaks.
(l) Recheck the coolant level and refill as necessary.
±
COOLIING SYSTEM Check and Replacement of Engine CoolantCO±7
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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
CO±14
±
COOLIING SYSTEM Radiator
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SERVICE SPECIFICATIONS
SERVICE DATA
ThermostatValve opening temperature80±845C176±183 5F
Valve liftat 95 5C (203 5F) 10 mm0.39 in.
Radiator capRelief valve opening pressureSTD74±103 kPa
(0.75±1.05 kgf/cm, 10.7±14.9 psi)
Limit 59 kPa 0.6 kgf/cm 8.5 psi
On±vehicle
itifh
Oil pressure1,177±2,452 kPa
inspection for hy-
draulic cooling(12±25 kgf/cm, 171±356 psi)draulic cooling
fan
fan
Hydraulic pumpSpool valve45.8 mm1.803 in.
Rotor side clearanceSTD Drive rotor 0.02 mm0.0008 in.
Driven rotor 0.03 mm0.0012 in.
Limit Drive rotor 0.03 mm0.0012 in.
Driven rotor 0.04 mm0.0016 in.
Rotor body clearanceSTD 0.05±0.09 mm0.0020±0.0035 in.
Limit 0.10 mm0.0039 in.
Rotor tip clearanceSTD 0.02 mm0.0008 in.
Limit 0.03 mm0.0012 in.
Drive shaft bushing inside diameter17.00±17.05 mm0.6693±0.6713 in.
Drive shaft diameter16.97±16.98 mm0.6681±0.6685 in.
Drive shaft oil clearanceSTD 0.02±0.08 mm0.0008±0.0031 in.
Limit 0.08 mm0.0031 in.
Drive shaft preload (rotating torque)0.3 N Vm 3.0 kgf Vcm 2.6 in. Vlbf
Solenoid valve resistanceat cold 7.5±8.5

Hydraulic motorRotor side clearanceSTD0.01±0.04 mm0.0004±0.0016 in.
Limit 0.05 mm0.0020 mm
Drive shaft hole inside diameter14.000±14.011 mm0.5512±0.5516 in.
Drive shaft diameter13.973±13.984 mm0.5501±0.5506 in.
Drive shaft oil clearanceSTD 0.016±0.038 mm0.0006±0.0015 in.
Limit 0.04 mm0.0031 in.
Drive shaft preload (rotating torque)0.3 NVm 3.0 kgf Vcm 2.6 in. Vlbf
Water temp. Resistanceat 80 5C (176 5F)1.48±1.58 k

sensor
CO±64±
COOLIING SYSTEM Service Specifications
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