width LEXUS SC300 1991 Service User Guide

(d) Check the valve overall length.
Standard overall length:Intake 94.95 mm (3.7382 in.)
Exhaust 96.90 mm (3.8150 in.)
Minimum overall length: Intake 94.45 mm (3.7185 in.)
Exhaust 96.40 mm (3.7953 in.)
If the overall length is less than minimum, replace the valve.
(e) Check the surface of the valve stem tip for wear.
If the valve stem tip is worn, resurface the tip with a grinder
or replace the valve.
NOTICE: Do not grind off more than the minimum overall
length.
8. INSPECT AND CLEAN VALVE SEATS (a) Using a 455 carbide cutter, resurface the valve seats.
Remove only enough metal to clean the seats.
(b) Check the valve seating position.
Apply a thin coat of prussian blue (or white lead) to the valve
face. Lightly press the valve against the seat. Do not rotate
the valve.
(c) Check the valve face and seat for the following:w If blue appears 3605 around the face, the valve is
concentric. If not, replace the valve.
w If blue appears 3605 around the valve seat, the
guide and face are concentric. If not, resurface the
seat.
w Check that the seat contact is on the middle of the
valve face with the following width:
1.0±1.4 mm (0.039±0.055 in.)
If not, correct the valve seats as follows:
(1) If the seating is too high on the valve face, use 30 5
and 45 5 cutters to correct the seat.
±
ENGINE MECHANICAL Cylinder HeadsEM±83
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ASSEMBLY OF CYLINDER BLOCK
(See Components on page EM±131)
HINT:
w Thoroughly clean all parts to be assembled.
w Before installing the parts, apply new engine oil to all
sliding and rotating surfaces.
w Replace all gaskets, O±rings and oil seals with new
parts.
1. INSTALL MAIN BEARINGS HINT:
wMain bearings come in widths of 19.5 mm (0.768 in.) and
22.5 mm (0.886 in.). Install the 22.5 mm (0.886 in.)
bearings in the No.1 and No.5 cylinder block journal
positions with the main bearing caps. Install the 19.5
mm (0.768 in.) bearings in the other positions.
w Upper bearings have an oil groove and oil holes; lower
bearings do not.
(a) Align the bearing claw with the claw groove of the cylinder block, and push in the five upper bearings.
(b) Align the bearing claw with the claw groove of the main bearing cap, and push in the five lower bearings.
HINT: A number is marked on each main bearing cap indicat-
ing the installation position.
2. INSTALL UPPER THRUST WASHERS Install the two thrust washers under the No.3 journal position
of the block with the oil grooves facing outward.
EM±156
±
ENGINE MECHANICAL Cylinder Block
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SERVICE SPECIFICATIONS
SERVICE DATA
 Engine tune±up Battery specific gravity  1.27±1.29 g  (when fully charged at 205C (68 5F))  High±tension cord resistance Limit 25 k
per cord  Valve clearance Intake 0.15 ± 0.25 mm 0.006 ± 0.010 in.   Exhaust 0.25 ± 0.35 mm 0.010 ± 0.014 in.
  Ignition timing 8±12 5 BTDC @ idle
   (w/ Terminals TE1 and E1 connected)
  Idle speed 700 + 50 rpm
 


Intake
manifold 


at Idle speed 


 


60 kPa 450 mmHg 17.7 in.Hg
vacuum vacuum  
Compressionat 250 rpmSTD1,226 kPa (12.5 kgf/cm, 178 psi) or more pressure  Limit 981 kPa 10.0 kgf/cm 142 psi  Difference of pressure between each cylinder 98 kPa (1.0 kgf/cm, 14 psi) or less Timing belt ten- Protrusion from housing end 10.5 ± 11.5 mm 0.413 ± 0.453 in. g
sioner g  
 Cylinder head Warpage Cylinder block side Limit 0.10 mm 0.0039 in.
 
y
 Manifold side Limit 0.10 mm 0.0039 in.
  Valve seat Refacing angle 30
5, 45 5, 75 5
  Contacting angle 455
Contacting width1.0 ± 1.4 mm0.039 ± 0.055 in.  Cylinder head bolt thread outside diam4eter 
   STD 9.770 ± 9.960 mm 0.3846 ± 0.3921 in.   Limit 9.60 mm 0.3780 in. Valve guide Inside diameter 6.010 ± 6.030 mm 0.2366 ± 0.2374 in.
 
g
bushing Outside diameter (for repair part) STD 11.048 ± 11.059 mm 0.4350 ± 0.4354 in.
 
g
  O/S 0.05 11.098 ± 11.109 mm 0.4369 ± 0.4374 in.
 Valve Valve overall length STD Intake 94.95 mm 3.7382 in.
    Exhaust 96.90 mm 3.8150 in.
LimitIntake94.45 mm3.7185 in.    Exhaust 96.40 mm 3.7953 in.  Valve face angle   44.5 5  Stem diameter  Intake 5.970 ± 5.985 mm 0.2350 ± 0.2356 in.    Exhaust 5.965 ± 5.980 mm 0.2356 ± 0.2354 in.
  Stem oil clearance STD Intake 0.025 ± 0.060 mm 0.0010 ± 0.0024 in.
    Exhaust 0.030 ± 0.065 mm 0.0012 ± 0.0026 in.
   Limit Intake 0.08 mm 0.0031 in.
Exhaust0.10 mm0.0039 in.  Margin thickness  STD 1.0 mm 0.039 in.    Limit 0.5 mm 0.020 in. Valve spring Squareness Limit 2.0 mm 0.079 in. g Free length  43.6 mm 1.717 in.
  Installed tension at 32.9 mm (1.295 in.) 186±206 N 
    (19.0 ± 21.0 kgf, 41.9 ± 46.3 lbf)
 Valve lifter Lifter diameter 30.966±30.976 mm 1.2191±1.2195 in.
  Lifter bore diameter  31.000±31.016 mm 1.2205±1.2211 in.
Oil clearanceSTD0.024±0.050 mm0.0009±0.0020 in.   Limit 0.07 mm 0.0028 in.
EM±178±
ENGINE MECHANICAL Service Specifications
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Diag. Code 14, 15Ignition Signal Circuit
CIRCUIT DESCRIPTION
The ECU determines the ignition timing, turns on Tr1 at a predetermined angle (5CA) before the desired
ignition timing and outputs an ignition signal (IGT) º1º to the \
igniter.
Since the width of the IGT signal is constant, the dwell angle control circuit in the ignit\
er determines the
time the control circuit starts primary current flow to the ignition coil bas\
ed on the engine rpm and ignition
timing one revolution ago, that is, the time the Tr2 turns on.
When it reaches the ignition timing, the ECU turns Tr1 off and outputs the IGT signal ºOº.
This turns Tr2 off, interrupting the primary current flow and generating a high voltage i\
n the secondary coil
which causes the spark plug to spark. Also, by the counter electromotive force\
generated when the primary
current is interrupted, the igniter sends an ignition confirmation signal (IGF\
) to the ECU.
The ECU stops fuel injection as a fail safe function when the IGF signal\
is not input to the ECU.
Code No.Diagnostic Code Detecting ConditionTrouble Area
14No IGF1 signal to ECU for 8±11 consecutive
IGT1 signal.
w Open or short in IGF1 and IGT1 circuit from
No. 1 igniter ± ECU.
w No. 1 igniter
w ECU
15No IGF2 signal to ECU for 8±11 consecutive
IGT2 signal.
wOpen or short in IGF2 and IGT2 circuit from
No. 2 igniter ± ECU.
w No. 2 igniter
w ECU
HINT: No. 1 igniter is for left bank and No. 2 igniter is for right bank.
WIRING DIAGRAM
TR±54±
ENGINE TROUBLESHOOTING Circuit Inspection
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PREPARATION
SST (SPECIAL SERVICE TOOLS)
RS00X±04
RECOMMENDED TOOLS
RSOOY±04
EQUIPMENT
RS00Z±04\
 \
Torque wrench 
\
 
\

\
Bolt Length: 35 mm (1.38 in.) Pitch: 1.0 mm (0.039 in.)
Diam.: 6.0 mm (0.236 in.) 

Airbag disposal
\
 \
Tire Width: 185 mm (7.28 in.) Inner diam.: 360mm (14.17 in.) Airbag disposal
\
 
\

\

Tire with disk wheel Width: 185 mm (7028 in.)
Inner diam.: 360 mm (14.17 in.) 


Airbag disposal
\
 \
Vinyl bag Airbag disposal
±
SUPPLEMENTAL RESTRAINT SYSTEM PREPARATIONRS±15
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6. COVER STEERING WHEEL PAD WITH CARDBOARDBOX OR TIRES
Covering Method Using Cardboard Box:
Cover the steering wheel pad with the cardboard box and
weigh the cardboard box down in four places with a at least
196 N (20 kgf, 44 lbf).
Size of cardboard box:
Must exceed the following dimensions±
x = 460 mm (18.11 in.) When dimension y of the cardboard box exceeds the
diameter of the disc wheel with tire the steering wheel
pad is tied to±
x = 460 mm (18.11 in.) + width of tire
y = 650 mm (25.59 in.)
NOTICE: If a cardboard box smaller than the size speci-
fied is used, the cardboard box will be broken by the
shock of the airbag deployment.
Covering Method Using Tires:
Place at least 3 tires without disc wheel on top of the disc
wheel with tire to which the steering wheel pad is tied.
Tire size: Must exceed the following dimensions± Width 185 mm (7.28 in.)
Inner diam 360 mm (14.17 in.)
CAUTION: Do not use tires with disc wheels.
NOTICE: The tires by marked by the airbag deployment,
so use redundant tires.
7. AIRBAG DEPLOYMENT
(a) Connect the SST red clip to the battery positive (+) terminal and the black clip to the battery negative (±) terminal.
(b) Confirm that no±one is within 10 m (33 ft) of the disc wheel the steering wheel pad is tied to.
(c) Press the SST activation switch and deploy the airbag. HINT: The airbag deploys simultaneously as the LED of the
SST activation switch lights up.
RS±26±
SUPPLEMENTAL RESTRAINT SYSTEM STEERING WHEEL PAD AND SPIRAL CABLE
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CAUTION: If a wire harness which is too thin or some oth-
er thing is used to tie down the front passenger airbag as-
sembly, it may be snapped by the shock when the airbag
is deployed, this is highly dangerous.
Always use a wire harness for vehicle use which is at
least 1.25 mm
2 (0.0019 in)2.
(1) Wrap the wire harness around the tire, passing the wire
harness at least 3 times through the installation hole on
the left and right sides of the front passenger airbag as-
sembly.
(2) Position the front passenger airbag assembly inside the tire with the airbag door facing inside.
Tie the wire harness to the tire.
Tire size: Must exceed the following dimensions
Width 185 mm (7.28 in.)
Inner diam 360 mm (14.17 in.)
CAUTION:
wMake sure the wire harness is tight. It is very dangerous
if a loose wire harness results in the front passenger
airbag assembly coming free due to the shock of the
airbag deploying.
w Always tie down the front passenger airbag assembly
with the airbag door facing inside.
NOTICE: The tire will be marked by the airbag deploy-
ment, so use a redundant tire.
3. CONFIRM FUNCTIONING OF SST (See page RS±27)
SST 09082±00700
RS±38
±
SUPPLEMENTAL RESTRAINT SYSTEM FRONT PASSENGER AIRBAG ASSEMBLY
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(d) With the center of the sleeve correctly placed between thecrimping jaws, squeeze the crimping tool until either end
comes into contact at the section marked by ªCLOSE HEREº.
HINT: Check to see that the sleeve and wires are still in the
correct position before closing the crimping tool ends with
steady pressure.
(e) Pull the joined wires to either end. Make sure that they are joined firmly by the sleeve.
NOTICE: If the joined wires come loose the splice is de-
fective, so replace the sleeve and repeat the procedure.
(f) Crimp both ends of the sleeve with the crimping tool at the ªINSº position.
4. PROTECT JOINED SECTION Wrap silicon tape around the joins to protect them from water.
HINT:
wBefore starting the operation, throughly wipe dirt and
grease off the sections to be joined.
w If the adhesive surfaces of 2 tapes come in contact, they
will stick together and will not come apart, so do not
remove the backing film except when using the tape.
w Do not let oil and dust, etc., get on the tape surface.
(a) Ready about 100 mm (3.94 in.) of silicon tape (Part No. 08231±00045) and peel off the film.
(b) Stretch the silicon tape until its width is reduced by half.
(c) About 10 mm (0.39 in.) from the end of the pressure contact
sleeve, wrap the silicon tape around the sleeve 3 or more
times while stretching the tape.
RS±50
±
SUPPLEMENTAL RESTRAINT SYSTEM WIRE HARNESS AND CONNECTOR
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Diag. Code 14, 15Ignition Signal Circuit
CIRCUIT DESCRIPTION
The ECU determines the ignition timing, turns on Tr1 at a predetermined angle (5CA) before the desired
ignition timing and outputs an ignition signal (IGT) º1º to the \
igniter.
Since the width of the IGT signal is constant, the dwell angle control circuit in the ignit\
er determines the
time the control circuit starts primary current flow to the ignition coil bas\
ed on the engine rpm and ignition
timing one revolution ago, that is, the time the Tr2 turns on.
When it reaches the ignition timing, the ECU turns Tr1 off and outputs the IGT signal ºOº.
This turns Tr2 off, interrupting the primary current flow and generating a high voltage i\
n the secondary coil
which causes the spark plug to spark. Also, by the counter electromotive force\
generated when the primary
current is interrupted, the igniter sends an ignition confirmation signal (IGF\
) to the ECU.
The ECU stops fuel injection as a fail safe function when the IGF signal\
is not input to the ECU.
Code No.Diagnostic Code Detecting ConditionTrouble Area
14No IGF1 signal to ECU for 8±11 consecutive
IGT1 signal.
w Open or short in IGF1 and IGT1 circuit from
No. 1 igniter ± ECU.
w No. 1 igniter
w ECU
15No IGF2 signal to ECU for 8±11 consecutive
IGT2 signal.
wOpen or short in IGF2 and IGT2 circuit from
No. 2 igniter ± ECU.
w No. 2 igniter
w ECU
HINT: No. 1 igniter is for left bank and No. 2 igniter is for right bank.
WIRING DIAGRAM
TR±54±
ENGINE TROUBLESHOOTING Circuit Inspection
WhereEverybodyKnowsYourName

Diag. Code 14, 15Ignition Signal Circuit
CIRCUIT DESCRIPTION
The ECU determines the ignition timing, turns on Tr1 at a predetermined angle (5CA) before the desired
ignition timing and outputs an ignition signal (IGT) º1º to the \
igniter.
Since the width of the IGT signal is constant, the dwell angle control circuit in the ignit\
er determines the
time the control circuit starts primary current flow to the ignition coil bas\
ed on the engine rpm and ignition
timing one revolution ago, that is, the time the Tr2 turns on.
When it reaches the ignition timing, the ECU turns Tr1 off and outputs the IGT signal ºOº.
This turns Tr2 off, interrupting the primary current flow and generating a high voltage i\
n the secondary coil
which causes the spark plug to spark. Also, by the counter electromotive force\
generated when the primary
current is interrupted, the igniter sends an ignition confirmation signal (IGF\
) to the ECU.
The ECU stops fuel injection as a fail safe function when the IGF signal\
is not input to the ECU.
Code No.Diagnostic Code Detecting ConditionTrouble Area
14No IGF1 signal to ECU for 8±11 consecutive
IGT1 signal.
w Open or short in IGF1 and IGT1 circuit from
No. 1 igniter ± ECU.
w No. 1 igniter
w ECU
15No IGF2 signal to ECU for 8±11 consecutive
IGT2 signal.
wOpen or short in IGF2 and IGT2 circuit from
No. 2 igniter ± ECU.
w No. 2 igniter
w ECU
HINT: No. 1 igniter is for left bank and No. 2 igniter is for right bank.
WIRING DIAGRAM
TR±54±
ENGINE TROUBLESHOOTING Circuit Inspection
WhereEverybodyKnowsYourName