coolant temperature LEXUS SC300 1991 Service User Guide

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
±
COOLIING SYSTEM ThermostatCO±13
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(3) Upper radiator hose or radiator
(4) Reservoir hose to radiator
5. INSTALL BATTERY
6. FILL ENGINE WITH COOLANT (See page CO±5)
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)
7. (A/T)
CHECK AUTOMATIC TRANSMISSION FLUID LEVEL (See pageMA±11 )
NOTICE: Do not overfill.
8. START ENGINE AND CHECK FOR LEAKS
9. INSTALL ENGINE UNDER COVER
SERVICE SPECIFICATIONS
SERVICE DATA
ThermostatValve opening temperature80±84 5c176±183 5F
Valve liftat 95 5C (203 5F) 8.5 mm0.335 in.
Radiator capRelief valve opening pressureSTD74±103 kPa
(0 75 1 05 k f/ 10 7 14 9 i)(0.75±1.05 kgf/cm, 10.7±14.9 psi)
Limit59 kPa0.6 kgf/cm28.5 psi
TORQUE SPECIFICATIONS
Part tightenedN
mkgf
cmft
lbf
Engine drain plug X Cylinder block2930022
Water pump X Cylinder block2121015
Water pump X Water by±pass pipe2121015
Water by±pass outlet X Cylinder head 8.89078 in.
lbf
Water inlet X Water pump 8.89078 in.
lbf
Oil cooler X Radiator lower tank (A/T) 8.38574 in.
lbf
Oil cooler X Pipe (A/T)1515011
Radiator fan shroud X Radiator 4.95043 in.
lbf
Radiator X Body121209
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COOLING SYSTEM Radiator, Service SpecificationsCO±21
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(Water Temperature Sensor)
COMPONENTS FOR REMOVAL AND
INSTALLATION
INSPECTION OF WATER TEMPERATURE
SENSOR
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OFBATTERY
CAUTION: Work must be started after 20 seconds or
longer from the time the ignition switch is turned to the
ºLOCKº position and the negative (±) terminal cable is
disconnected from the battery.
2. REMOVE ENGINE UNDER COVER
3. DRAIN ENGINE COOLANT (See page CO±6)
4. REMOVE WATER TEMPERATURE SENSOR (a) Disconnect the water temperature sensor connector.
(b) Remove the water temperature sensor from left side ofthe radiator lower tank.
(c) Remove the O±ring from the water temperature sensor.
CO±62
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COOLIING SYSTEM Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)
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5. INSPECT WATER TEMPERATURE SENSORUsing an ohmmeter, measure the resistance between the ter-
minals.
Resistance: 1.48±1.58 k
at 80 5C (176 5F)
If the resistance is not as specified, replace the sensor.
6. REINSTALL WATER TEMPERATURE SENSOR (a) Install a new O±ring to the water temperature sensor.
(b) Apply soapy water to the O±ring.
(c) Install the water temperature sensor to the radiator.
Torque: 7.4 N Vm (75 kgf Vcm, 65 in. Vlbf)
(d) Connect the water temperature sensor connector.
7. REFILL WITH ENGINE COOLANT (See page CO±7)
8. REINSTALL ENGINE UNDER COVER
9. RECONNECT CABLE FROM NEGATIVE TERMINAL OF BATTERY
(A/C High±Pressure Switch)
INSPECTION OF A/C HIGH±PRESSURE
SWITCH
1. DISCONNECT HIGH±PRESSURE SWITCH CONNECTOR
2. INSTALL MANIFOLD GAUGE SET (See AC section)
3. INSPECT HIGH±PRESSURE SWITCH(a) Wh e n th e A/C switch is OFF, ch e ck th a t th e re iscontinuity between terminals 2 and 3. (When the
pressure is 1,226 kPa (12.5 kgf/cm
2, 178 psi) or lower.)
(b) When the A/C switch and blower switch are ON, check
that there is no continuity between terminals 2 and 3.
(When the pressure is 1,520 kPa (15.5 kgf/cm
2, 220 psi)
or higher.)
If continuity is not as specified, replace the switch.
4. REMOVE MANIFOLD GAUGE SET
5. RECONNECT HIGH±PRESSURE SWITCH CONNECTOR
(Solenoid Valve)
(See page CO±36)
±
COOLIING SYSTEM Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)CO±63
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EXHAUST GAS RECIRCULATION (EGR) SYSTEM
DESCRIPTION
To reduce NOx emission, part of the exhaust gases are recirculated through\
the EGR valve to the intake man-
ifold to lower the maximum combustion temperature.
OPERATION
To reduce NOx emission, part of the exhaust gases are recirculated through\
the EGR valve to the intake manifold to lower the
maximum combustion temperature.
Coolant
Temp.VSVThrottle Valve OpeningPressure in the EGR Valve Pressure ChamberEGR VacuumModulatorEGR
ValveExhaust Gas
Below 45
COPENCLOSEDNot recircu-
(113
F)OPEN±±±CLOSEDlated
Positioned be-
low EGR port±±CLOSEDNot recircula- ted
Above 50 5C
(122 5F)CLOSEDPositioned be-
tween EGRport
(1)
LOW* Pressure constantly
alternating between
OPENS passage to atmosphereCLOSEDNot recircula- ted
tween EGR port
and R port(2)
HIGHalternating between
low and highOPENS passage
to atmosphereOPENRecirculated
Above 50 5C
(122 5F)CLOSEDPositioned
above R port(3)
HIGH**CLOSES passage to atmosphereOPENRecirculated(increase)
* Pressure increases Modulator closes EGR valve opens Pressure drops EGR Valve closes Modulator opens
** When the throttle valve is positioned above the R port, the EGR vacuum m\
odulator will close the atmosphere passage and
open the EGR valve to increase the EGR gas, even if the exhaust pressure\
is insufficiently low.
±
EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) SystemEC±11
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EXHAUST GAS RECIRCULATION (EGR) SYSTEM
DESCRIPTION
To reduce NOx emission, part of the exhaust gases are recirculated through\
the EGR valve to the intake
manifold to lower the maximum combustion temperature.
OPERATION
Coolant Temp.ConditionEGR ValveExhaust Gas
Below 53 5C (127 5F)±CLOSEDNot recirculated
Above 55 5C (131 5F)(a)Idling, Deceleration, Neutral,
Low air volume, High Engine speedCLOSEDNot recirculatedAbove 55 C (131 F)
Except (a)OPEN*Recirculated
* The ECU calculates the appropriate number of steps according to the in\
take air volume and the engine speed, then
drives the stepping motor to maintain the EGR volume at a level appropri\
ate to the driving conditions.

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EMISSION CONTROL SYSTEMS Exhaust Gas Recirculation (EGR) SystemEC±15
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The 1 UZ±FE engine has 8±cylinders in a V±arrangement at a bank an\
gle of 905. From the front of the RH
bank cylinders are numbered 2 ± 4 ± 6 ± 8, and from the front of t\
he LH bank cylinders are 1 ± 3 ± 5 ± 7.
The crankshaft is supported by 5 bearings inside the crankcase. These beari\
ngs are made of a copper and
lead alloy.
The crankshaft is integrated with 8 weights for balance. Oil holes are plac\
ed in the center of the crankshaft
to supply oil to the connecting rods, bearing, pistons and other component\
s.
The ignition order is 1 ± 8 ± 4 ± 3 ± 6 ± 5 ± 7 ± 2. T\
he cylinder head is made of alminum alloy, with a cross
flow type intake and exhaust layout and with pent±roof type combustion chambers. The spark plugs are
located in the center of the combustion chambers.
At the front and rear of the intake manifold, a water passage has been p\
rovided which connects the RH
and LH cylinder heads.
Exhaust and intake valves are equipped with irregular pitch springs made\
of special valve spring carbon
steel which are capable of functioning at all engine speeds.
The RH and LH intake camshaft are driven by a timing belt, and a gear on\
the intake camshaft engages
with a gear on the exhaust camshaft to drive it. The cam journal is supp\
orted at 5 (intake) or 4 (exhaust)
places between the valve lifters of each cylinder and on the front end o\
f the cylinder head. Lubrication of
the cam journals and gears is accomplished by oil being supplied through th\
e oiler port in the center of the
camshaft.
Adjustment of the valve clearance is done by means of an outer shim type\
system, in which valve adjusting
shims are located above the valve lifters. This permits replacement of the sh\
ims without removal of the
camshafts.
Pistons are made of high temperature±resistant aluminum alloy, and a depression is built into the piston
head to prevent interference with the valves.
Piston pins are the full±floating type, with the pins fastened to neither the piston boss nor the connecting
rods. Instead, snap rings are fitted on both ends of the pins, preventing the\
pins from falling out.
The No.1 compression ring is made of steel and the No.2 compression ring\
is made of cast iron. The oil
ring is made of a combination of steel and stainless steel. The outer diamet\
er of each piston ring is slightly
larger than the diameter of the piston and the flexibility of the rings allows them to hug the cylinder walls
when they are mounted on the piston. Compression rings No.1 and No.2 work to\
prevent gas leakage from
the cylinder and the oil ring works to scrape oil off the cylinder walls to prevent it from entering the combus-
tion chambers.
The cylinder block is made of aluminum alloy with a bank of 90 5. Cast iron cylinders are installed inside
the cylinder block. It has 8 cylinders which are approximately twice the le\
ngth of the piston stroke. The top
of each cylinder is closed off by the cylinder head and the lower end of the cylinders becomes the crank-
case, in which the crankshaft is installed. In addition, the cylinder block c\
ontains a water jacket, through
which coolant is pumped to cool the cylinders.
The No.1 and No.2 oil pans are bolted onto the bottom of the cylinder bl\
ock. The No.1 oil pan is made of
aluminum alloy. The No.2 oil pan is an oil reservoir made of pressed steel sheet. An o\
il level sensor is
installed in the No.1 oil pan (If oil level drops below a set level, a warning light\
s up.). And oil pan baffle plate
keeps sufficient oil in the bottom of the No.2 oil pan even when the vehicle is t\
ilted. This dividing plate also
prevents the oil from marking waves when the vehicle is stopped suddenly\
and the oil shifts away from the
oil pump suction pipe.
Plastic region tighten bolts are used for the cylinder head, main bearin\
g cap and connecting rod.
EG±4
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1UZ±FE ENGINE ENGINE MECHANICAL
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TUNE±UP
EG10Z±05
ENGINE COOLANT INSPECTION
1. CHECK ENGINE COOLANT LEVEL AT RESERVOIR TANK
The coolant level should be above the ªCOLD LEVELº at nor-
mal temperature (20 5C (68 5F)).
If low, check for leaks and add coolant up to the ªCOLD LEV-
ELº
2. CHECK ENGINE COOLANT QUALITY
(a) Remove the radiator cap from the reservoir tank.
CAUTION: To avoid the danger of being burned, do not remove
it while the engine and radiator are still hot as fluid and steam
can be blown out under pressure
(b) There should not be any excessive deposits of rust or scale 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.
Capacity (w/ Heater):
10.8 liters (11.4 US qts, 9.5 lmp. qts)
HINT:
wUse a good brand of ethylene±glycol base coolant and
mix it according to the manufacturer's directions.
w Using coolant which includes more than 50%
ethylene±glycol(but not more than 70%) is
recommended.
NOTICE:
w Do not use a alcohol type coolant.
w The coolant should be mixed with demineralized water or
distilled water.
(c) Reinstall the radiator cap.
±
1UZ±FE ENGINE ENGINE MECHANICALEG±9
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12. REMOVE RADIATOR RESERVOIR TANK(a) Disconnect the coolant level sensor connector.
(b) Disconnect the following hoses:(1) Reservoir hose to water inlet housing
(2) Reservoir hose to 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.
13. REMOVE RADIATOR (a) Disconnect the water temperature sensor connector.
(b) Disc onnect the wire clamp (for water temperature
sensor) from the radiator fan shrould.
(c) Disconnect the following hoses: (1) Two oil cooler hoses (for cooling fan) from pipes
(2) Two radiator hoses
EM±120
±
ENGINE MECHANICAL Cylinder Block
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The 1 UZ±FE engine has 8±cylinders in a V±arrangement at a bank an\
gle of 905. From the front of the RH
bank cylinders are numbered 2±4±6±8, and from the front of the LH b\
ank cylinders are numbered 1 ±3±5±7.
The crankshaft is supported by 5 bearings specified by the inside of the cr\
ankcase. These bearings are made
of a copper and lead alloy. The crankshaft is integrated with 8 weights which are cast along with it\
for balancing. Oil holes are built
into the center of the crankshaft for supplying oil to the connecting ro\
ds, pistons and other components. The ignition order is 1±8±4±3±6±5±7±2. The cylinder\
head is made of aluminum alloy, with a cross flow
type intake and exhaust layout and with pent±roof type combustion chambers. The spark plugs are loca\
ted in
the center of the combustion chambers.
At the front and rear of the intake manifold, a water passage has been p\
rovided which connects the RH
and LH cylinder heads. Exhaust and intake valves are equipped with irregular pitch springs made\
of special valve spring carbon
steel which are capable of following no matter what the engine speed.
The RH and LH intake camshafts are driven by a single timing belt, and a ge\
ar on the intake camshaft en-
gages with a gear on the exhaust camshaft to drive it. The camshaft jour\
nal is supported at 5 (intake) or 4 (ex-
haust) places between the valve lifters of each cylinder and on the front end of the cylinder \
head. Lubrication
of the cam journal gear is accomplished by oil being supplied through the \
oiler port in the center of the camshaft. Adjustment of the valve clearance is done by means of an outer shim type\
system, in which valve adjusting
shims are located above the valve lifters. This permits replacement of the sh\
ims without removal of the cam-
shafts. Pistons are made of high temperature±resistant aluminum alloy, and a depression is built into the piston
head to prevent interference with valves.
Piston pins are the full±floating type, with the pins fastened to neither the piston boss nor the connecting
rods. Instead, snap rings are fitted on both ends of the pins, preventing the\
pins from falling out. The No.1 compression ring is made of steel and the No.2 compression ring\
is made of cast iron. The oil
ring is m ade of a combination of steel and stainless steel. The outer diameter of\
each piston ring is slightly larger
than the diameter of the piston and the flexibility of the rings allows them\
to hug the cylinder walls when they
are mounted on the piston. Compression rings No.1 and No.2 work to prevent \
the leakage of gas from the cylin-
der and the oil ring works to scrape oil off the cylinder walls to prevent it from entering the combustion chamber. The cylinder block is made of aluminum alloy with a bank angle of 90 5. Cast iron cylinders are installed
inside the cylinder block. It has 8 cylinders which are approximately twice the length of th\
e piston stroke. The
top of each cylinder is closed off by the cylinder heads and the lower end of the cylinders becomes the crank-
case, in which the crankshaft is installed. In addition, the cylinder bl\
ock contains a water jacket, through which
coolant is pumped to cool the cylinders. The No.1 and No.2 oil pans are bolted onto the bottom of the cylinder block\
. The No.1 oil pan is made of
aluminum alloy. The No.2 oil pan is an oil reservoir made of pressed steel sheet. An o\
il level sensor is installed
in the No.1 oil pan (If the oil level drops below a set level, a warnin\
g light lights up.). A oil pan baffle plate keeps
sufficient oil in the bottom of the No.2 oil pan even when the vehicle is tilted. \
This dividing plate also prevents
the oil from making waves when the vehicle is stopped suddenly and the oil \
shifts away from the oil pump suction
pipe. Plastic region tightening bolts are used for the cylinder head, main bearing ca\
p and connecting rod.
EM±4
±
ENGINE MECHANICAL Operation
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