1991 LEXUS SC400 oil change

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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31. INSTALL THROTTLE BODY COVERInstall the throttle body cover and hose clamp with the two
bolts and cap nut.
32. INSTALL DRIVE BELT Install the drive belt by turning the drive belt tensioner coun-
terclockwise.
HINT: The pulley bolt for the belt tensioner has a left±hand
thread.
33. INSTALL BATTERY
34. FILL WITH ENGINE COOLANT (See page CO±7)
35. FILL COOLING FAN RESERVOIR TANK WITH FLUID (See page CO±23)
36. FILL WITH ENGINE OIL (See page LU±7)
Capacity:
Drain and refill
w/Oil filter change4.8 liters (5.1 US qts, 4.2 lmp. qts)
w/o Oil filter change 4.5 liters (4.8 US qts, 4.0 lmp. qts)
Dry fill 6.0 liters (6.3 US qts, 5.3 lmp. qts)
37. START ENGINE AND CHECK FOR LEAKS
38. CHECK AUTOMATIC TRANSMISSION FLUID LEVEL
39. CHECK IGNITION TIMING (See page IG±28)
Ignition timing:
8±125 BTDC @ idle
(w/ Terminals TE1 and E1 connected)
40. INSTALL ENGINE UNDER COVER
41. INSTALL HOOD
42. PERFORM ROAD TEST Check for abnormal noise, shock, slippage, correct shift
points and smooth operation.
32. RECHECK ENGINE COOLANT AND ENGINE OIL LEVELS
±
ENGINE MECHANICAL Cylinder BlockEM±177
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A pressure feeding lubrication system has been adopted to supply oil to \
the moving parts of this engine. The
lubrication system consists of an oil pan, oil pump, oil filter and other external p\
arts which supply oil to the moving
parts in the engine block. The oil circuit is shown in the illustration at th\
e top of the previous page. Oil from the
oil pan is pumped up by the oil pump. After it passes through the oil fi\
lter, it is fed through the various oil holes
in the crankshaft and cylinder block. After passing through the cylinder b\
lock and performing its lubricating func-
tion, the oil is returned by gravity to the oil pan. A dipstick on the center\
left side of the cylinder block is provided
to check the oil level.
OIL PUMP The oil pump pumps up oil from the oil pan and sends it under pressure to t\
he various parts of the engine.
An oil strainer is mounted in front of the inlet to the oil pump. The oil \
pump itself is a trochoid type pump, inside
of which there is a drive rotor and a driven rotor. When the drive rotor rotates, the driven rotor rotates in the same
direction, and since the axis of the driven rotor shaft is different from the center of the driven rotor, the space
between the two rotors is changed as they rotate. Oil is drawn in when the space\
is wide and is discharged when
the space in narrow.
OIL PRESSURE REGULATOR At high engine speeds, the engine oil supplied by the oil pump exceeds the\
capacity of the engine to utilize
it. For that reason, the oil pressure regulator works to prevent an over\
supply of oil. During normal oil supply, a
coil spring and valve keep the bypass closed, but when too much oil is being \
fed, the pressure become extremely
high, overpowering the force of the spring and opening the valves. This allow\
s the excess oil to flow through
the valve and return to the oil pump inlet.
OIL FILTER The oil filter is a full flow type filter with a built±in paper filter e\
lement. Particles of metal from wear, airborne
dirt, carbon and other impurities can get into the oil during use and co\
uld cause accelerated wear or seizing if
allowed to circulate through the engine. The oil filter, integrated into the oil line, removes these impurities as the
oil passes through it. The filter is mounted outside the engine to simplify\
replacement of the filter element. A relief
valve is also included ahead of the filter element to relieve the high oil pr\
essure in case the filter element be-
comes clogged with impurities. The relief valve opens when the oil pressure o\
verpowers the force of the spring.
Oil passing through the relief valve by±passes the oil filter and flo\
ws directly into the main oil hole in the engine.
±
LUBRICATION SYSTEM PrecautionsLU±3
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PREPARATION
SST (SPECIAL SERVICE TOOLS)
RECOMMENDED TOOLS
EQUIPMENT
Part NameNote
Oil pressure gauge
Precision straight edgeOil pump
Torque wrench
LUBRICANT
Item
Capacity
ClassificationItemLitersUS qtslmp. qtsClassification
Engine oilAPI grade SG, Energy±Conserving II
Dry fill606353multigrade. Recommended viscosity is
Drain and refill6.06.35.3gy
as shown, with SAE 5W±30 being the
w/ Oil filter change 4.85.14.2preferred engine oil.
w/o Oil filter change4.54.85.3
g
SSM (SPECIAL SERVICE MATERIALS)
Part NamePart No.Use etc.
Seal packing or equivalent08826±00080Oil pump, Oil pan
Adhesive 1344,
Three bond 1344,08833±00080Oil pressure switch
Loctite 242 or equivalent
LU±4±
LUBRICATION SYSTEM System Circuit, Operation
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(d) Tighten the oil filter by hand until the rubber gasketcontacts the seat of the filter mounting. Then using SST,
give it an additional 3/4 turn to seat the oil filter.
SST 09228±07500
3. FILL WITH ENGINE OIL (a) Clean and install the oil drain plug with a new gasket.
Torque: 25 N Vm (250 kgf Vcm, 18 ft Vlbf)
(b) Fill with new engine oil.
Oil grade: See page LU±5
Capacity: Drain and refillw/ Oil filter change
4.8 liters (5.1 US qts, 4.2 lmp. qts)
w/o Oil filter change 4.5 liters (4.8 US qts, 4.0 lmp.qts)
Dry fill 6.0 liters (6.3 US qts, 5.3 lmp. qts)
(c) Reinstall the oil filler cap.
4. START ENGINE AND CHECK FOR LEAKS
5. RECHECK ENGINE OIL LEVEL (See page LU±5)
±
LUBRICATION SYSTEM Replacement of Engine Oil and Oil FilterLU±7
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CIRCUIT INSPECTIONDiag. Code 12
RPM Signal Circuit (No.1)
CIRCUIT DESCRIPTION
Cam position sensors (G1 and G2 signals) and engine speed sensor (NE sig\
nal) consist of a signal plate
and a pick up coil.
The G1, G2 signal plates have one tooth each on its outer circumference and\
are mounted on the left and
right bank camshafts.
When the camshafts rotate, the protrusion on the signal plate and the air gap on the pick up coil change,
causing fluctuations in the magnetic field and generating an electromotive forc\
e in the pick up coil.
The NE signal plate has 12 teeth and is mounted on the crankshaft. The NE s\
ignal sensor generates 12
NE signals per engine revolution. The ECU detects the standard crankshaf\
t angle based on the G1, G2
signals, and the actual crankshaft angle and the engine speed by the NE \
signals.
Code No.Diagnostic Code Detecting ConditionTrouble Area
wOpen or short in engine speed sensor, No. 1,w Oen or short in engine s eed sensor, No. 1,
No. 2 cam position sensor circuit
12No ºNEº or ºG1º and ºG2º signal to ECU
No. 2 cam osition sensor circuit
w Engine speed sensor12No NE or G1 and G2 signal to ECU
within 2 sec. after cranking.
wEngine s eed sensor
wNo. 1, No. 2 cam position sensorgNo. 1, No. 2 cam osition sensor
wStarter
wECU
TR±48±
ENGINE TROUBLESHOOTING Circuit Inspection
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(e) Using snap ring pliers, install a new snap ring.
5. AIR TIGHTNESS TEST
(a) Install SST to the unions of the rack housing.SST 09631±12071
(b) Apply 53.3 kPa (400 mmHg, 15.75 inVHg) of vacuum for about 30 seconds.
(c) Check that there is no change in the vacuum. If there is change in the vacuum, check the installation of the
rack housing oil seals.
6. INSTALL CONTROL VALVE
(a) Coat the teflon rings with power steering fluid.
(b) Push the control valve into the rack housing.
7. INSTALL CONTROL VALVE HOUSING
(a) Coat a new O±ring with power steering fluid, and install it to the valve housing.
(b) Using a hexagon wrench, tighten the 2 bolts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
NOTICE: To prevent oil seal lip damage, wind vinyl tape on the
serration part of the control valve shaft.
8. INSTALL LOWER BEARING AND SPACER
±
STEERING POWER STEERINGSR±159
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CIRCUIT INSPECTIONDiag. Code 12
RPM Signal Circuit (No.1)
CIRCUIT DESCRIPTION
Cam position sensors (G1 and G2 signals) and engine speed sensor (NE sig\
nal) consist of a signal plate
and a pick up coil.
The G1, G2 signal plates have one tooth each on its outer circumference and\
are mounted on the left and
right bank camshafts.
When the camshafts rotate, the protrusion on the signal plate and the air gap on the pick up coil change,
causing fluctuations in the magnetic field and generating an electromotive forc\
e in the pick up coil.
The NE signal plate has 12 teeth and is mounted on the crankshaft. The NE s\
ignal sensor generates 12
NE signals per engine revolution. The ECU detects the standard crankshaf\
t angle based on the G1, G2
signals, and the actual crankshaft angle and the engine speed by the NE \
signals.
Code No.Diagnostic Code Detecting ConditionTrouble Area
wOpen or short in engine speed sensor, No. 1,w Oen or short in engine s eed sensor, No. 1,
No. 2 cam position sensor circuit
12No ºNEº or ºG1º and ºG2º signal to ECU
No. 2 cam osition sensor circuit
w Engine speed sensor12No NE or G1 and G2 signal to ECU
within 2 sec. after cranking.
wEngine s eed sensor
wNo. 1, No. 2 cam position sensorgNo. 1, No. 2 cam osition sensor
wStarter
wECU
TR±48±
ENGINE TROUBLESHOOTING Circuit Inspection
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