lock LEXUS SC400 1991 Service Repair Manual

9. REMOVE NO. 3, NO. 1 AND NO. 2 CYLINDER HEADCOVERS
(a) Remove the 12 bolts and four nuts.
(b) Remove the cylinder head covers and gaskets.
10. SET NO. 1 CYLINDER TO TDC/COMPRESSION (a) Turn the crankshaft pulley and align its groove withtiming mark º0º of the No. 1 timing belt cover.
NOTICE: Always turn the crankshaft clockwise.
(b) Check that the timing marks of the camshaft timing pulleys are aligned with the timing marks of the No. 4
timing belt cover.
If not, turn the crankshaft one revolution (360 5).
11. INSPECT VALVE CLEARANCE (a) Uniformly tighten the bearing cap bolts in severalpasses.
Torque: 20 N Vm (200 kgf Vcm, 14 ft Vlbf)
(b) Check only those valves indicated in the illustration.
w Using a feeler gauge, measure the clearance
between the valve lifter and camshaft.
w Record the valve clearance measurements of
those that are out of specification. They will be used
later to determine the required replacement
adjusting shim.
Valve clearance (Cold):
Intake 0.15±0.25 mm (0.006±0.010 in.)
Exhaust 0.25±0.35 mm (0.010±0.014 in.)
EM±12±
ENGINE MECHANICAL Engine Tune±Up
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INSPECTION OF HIGH±TENSION CORDS
1. REMOVE HIGH±TENSION CORDS (See page IG±11)
2. INSPECT HIGH±TENSION CORDS (b) Using an ohmmeter, measure the resistance.
Maximum resistance: 25 k
per cord
If the resistance is greater than maximum, replace the cord.
3. REINSTALL HIGH±TENSION CORDS (See page IG±16)
INSPECTION OF DRIVE BELT
INSPECT DRIVE BELT
HINT: A belt tensioner is used, so checking the belt tension
is not necessary.
(a) Visually check the drive belt for excessive wear, frayedcords etc.
If necessary, replace the drive belt.
HINT:
w Cracks on rib side of a drive belt are considered
acceptable. If the drive belt has chunks missing from the
ribs, it should be replaced.
w The drive belt tension can be released by turning the
belt tensioner counterclockwise. The pulley bolt for the
belt tensioner has a left±hand thread.
(b) Check the belt tensioner operation. w Check that the belt tensioner moves downward
when the drive belt is pressed down at the points
indicated in the illustration with approx. 98 N (10
kgf, 22.0 lbf) of force.
w Check the alignment of the belt tensioner pulley to
make sure the drive belt has not slipped off the
pulley.
If necessary, replace the belt tensioner. w Check that the arrow mark on the belt tensioner
falls within area A of the scale.
If it is outside area A, replace the drive belt.
HINT:
w When a new belt is installed, it should lie within area B.
If not, the drive belt is not correct.
w After installing a belt, check that it fits properly in the
ribbed grooves.
w Check by hand to confirm that the belt has not slipped
out of the groove on the bottom of the pulley.
EM±10
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ENGINE MECHANICAL Engine Tune±Up
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INSPECTION AND ADJUSTMENT OF
VALVE CLEARANCE
HINT: Inspect and adjust the valve clearance when the
engine is cold.
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OF BATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
2. DRAIN ENGINE COOLANT (See page CO±6)
3. REMOVE THROTTLE BODY COVER (a) Remove the mounting cap nut.
(b) Loosen the two bolts, and remove the throttle body
cover.
4. DISCONNECT CONTROL CABLES FROM THROTTLE BODY
Disconnect the following cables:(1) Accelerator cable
(2) A/T throttle control cable
(3) (w/ Cruise Control System) Cruise control actuator cable
5. REMOVE INTAKE AIR CONNECTOR (a) Disconnect the following hoses:(1) Air hose from ISC valve
(2) Air hose (from PS air control valve) from intake
air connector
(b) Remove the bolt holding the intake air connector to the cylinder head cover.
(c) Loosen the two hose clamps.
(d) Disconnect the intake air connector from the throttle
body and air cleaner hose, and remove the throttle body.
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ENGINE MECHANICAL Engine Tune±UpEM±11
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Using compressed air and magnetic finger, removethe adjusting shim by blowing air into the shim hole.
HINT: Remove the adjusting shim from the intake man-
ifold side.
NOTICE: Do not drop the adjusting shim into por-
tions A and B. If dropped into portion A, the adjust-
ing shim will pass through the cylinder head and
cylinder block into the oil pan. If dropped into por-
tion B, the adjusting shim cannot be recovered with-
out removing the exhaust camshaft.
inspNFO
EM±18±
ENGINE MECHANICAL Engine Tune±Up
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REMOVAL OF TIMING BELT
(See Components on page EM±23)1. REMOVE WATER PUMP PULLEY AND RADIATOR (See steps 1 to 3, 6 and 7 on pages EM±64 and 66)
2. REMOVE NO. 3 AND NO. 2 TIMING BELT COVERS (a) Remove the oil filler cap.
(b) Using a 5 mm hexagon wrench, remove the nine bolts,No. 3, No. 2 timing belt covers and gasket.
3. REMOVE DRIVE BELT TENSIONER Remove the three bolts and tensioner.
4. SET NO. 1 CYLINDER TO TDC/COMPRESSION (a) Turn the crankshaft pulley and align its groove withtiming mark º0º of the No. 1 timing belt cover.
NOTICE: Always turn the crankshaft clockwise.
(b) Check that the timing marks of the camshaft timing pulleys are aligned with the timing marks of the No. 4
timing belt cover.
If not, turn the crankshaft one revolution (360 5).
5. REMOVE TIMING BELT FROM CAMSHAFT TIMING PULLEYS
HINT: (Re±using timing belt)
Place matchmarks on the timing belt and camshaft timing
pulleys as shown in the illustration.
EM±24
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ENGINE MECHANICAL Timing Belt
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INSPECTION OF TIMING BELT
COMPONENTS
1. INSPECT TIMING BELTNOTICE:w Do not bend, twist or turn the timing belt inside
out.
w Do not allow the timing belt to come into contact
with oil, water or steam.
w Do not make use of timing belt tension when
installing or removing the mount bolt of the
camshaft timing pulley.
If there are any defects as shown in the illustrations, check
the following points:
(a) Premature parting
w Check for proper installation.
w Check the timing cover gasket for damage and
proper installation.
(b) If the belt teeth are cracked or damaged, check to see if either the camshaft or water pump is locked.
(c) If there is noticeable wear or cracks on the belt face, check to see if there are nicks on the side of the idler
pulley lock.
(d) If there is wear or damage on only one side of the belt, check the belt guide and the alignment of each pulley.
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ENGINE MECHANICAL Timing BeltEM±27
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11. INSTALL TIMING BELT TENSIONER(a) Temporarily install the tensioner with the two bolts.
(b) Alternately tighten the two bolts.
Torque: 26 N Vm (270 kgf Vcm, 20 ft Vlbf)
(c) R e m o v e t h e 1 . 5 0 m m h e x agon wrench from the
tensioner with pliers.
12. CHECK VALVE TIMING (a) Turn the crankshaft pulley two revolutions from TDC toTDC.
NOTICE: Always turn the crankshaft clockwise.
(b) Check that each pulley aligns with the timing marks as shown in the figure.
If the marks do not align, remove the timing belt and reinstall
it.
13. INSTALL DRIVE BELT TENSIONER Install the tensioner with the three bolts.
Torque: 21 N Vm (210 kgf Vcm, 15 ft Vlbf)
NOTICE: Be careful not to drop the bolts inside the timing
belt cover.
EM±32
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ENGINE MECHANICAL REPAIR INSTRUCTIONS
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REMOVAL OF TIMING BELT
(See Components on pages EM±33 and 34)
1. REMOVE BATTERY CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ºLOCKº position and the negative (±) termi-
nal cable is disconnected from the battery.
2. REMOVE ENGINE UNDER COVER
3. DRAIN ENGINE COOLANT (See page CO±6)
4. REMOVE DRIVE BELT Loosen the drive belt tension by turning the drive belt tension-
er counterclockwise, and remove the drive belt.
HINT: The pulley bolt for the belt tensioner has a left±hand
thread.
5. REMOVE RESERVOIR TANK RADIATOR (See steps 12 and 13 on pages EM±120 and 121)
6. REMOVE A/C COMPRESSOR WITHOUT DISCONNECTING HOSES
(a) Disconnect the compressor connector.
(b) Remove the mounting nut, and disconnect the groundcable.
(c) Remove the mounting bolt and compressor stay.
(d) R e m o v e t h e t w o b o l t s , a n d d i s c onnect the A/C
compressor from the engine.
HINT: Put aside the compressor, and suspend it.
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ENGINE MECHANICAL Timing BeltEM±35
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(b) Check that the timing marks of the camshaft timingpulleys and timing belt rear plates aligned.
If not, turn the crankshaft one revolution (360 5).
27. REMOVE TIMING BELT TENSIONER HINT:
w(Re±using timing belt)
If the installation marks have disappeared, before re-
moving the timing belt, place new installation marks on
the timing belt to match the timing marks of the camshaft
timing pulleys, and place a new installation mark on the
timing belt to match the end of the hydraulic pump.
w (When replacing timing belt tensioner only)
To avoid meshing of the timing pulley and timing belt, se-
cure one of them with string. And place matchmarks on
the timing belt and RH camshaft timing pulley.
Alternately loosen the two bolts, and remove them, the ten-
sioner and dust boot.
28. DISCONNECT TIMING BELT FROM CAMSHAFT TIMING PULLEYS
(a) Using SST, loosen the tension between the LH and RHcamshaft timing pulleys by slightly turning the LH
camshaft timing pulley clockwise.
SST 09278±54012
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ENGINE MECHANICAL Timing BeltEM±41
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(b) If the belt teeth are cracked or damaged, check to seeif either the camshaft is locked.
(c) If there is noticeable wear or cracks on the belt face, check to see if there are nicks on the side of the idler
pulley lock and water pump.
(d) If there is wear or damage on only one side of the belt, check the belt guide and the alignment of the each
pulley.
(e) If there is noticeable wear on the belt teeth, check timing belt cover for damage, correct gasket installation. and
the foreign material on the pulley teeth.
If necessary, replace the timing belt.
2. INSPECT IDLER PULLEYS Check the turning smoothness of the idler pulley.
If necessary, replace the idler pulley.
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ENGINE MECHANICAL Timing BeltEM±45
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