1991 LEXUS SC300 timing belt

INSPECTION AND ADJUSTMENT OF
VALVE CLEARANCE
HINT: Inspect and adjust the valve clearance when the en-
gine is cold.
1. DISCONNECT CABLE FROM NEGATIVE TERMINAL OF BATTERY
CAUTION: Turn the ignition switch to ºLOCKº. Discon-
nect the cable from the negative (±) terminal of the bat-
tery. Wait at least 20 seconds before procceding with
work.
2. DISCONNECT CONTROL CABLES FROM THROTTLE BODY
Disconnect the following cables:(1) Accelerator cable
(2) (A/T) Throttle control cable
(3) Cruise control actuator cable
3. REMOVE AIR CLEANER HOSE (a) Disconnect the following hoses:(1) PS air hose from No.
4 timing belt cover
(2) PCV hose from No. 2 cylinder head cover
(b) Loosen the two hose clamps and remove the air cleaner
hose.
4. REMOVE EGR PIPE (a) Loosen the union nut.
(b) Remove the two bolts, EGR pipe and gasket.
5. REMOVE THROTTLE BODY BRACKET Remove the four nuts and throttle body bracket.
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6. REMOVE THROTTLE BODY WITH INTAKE AIRCONNECTOR
(a) Disconnect the following hoses and connectors:(1) PCV hose
(2) Three vacuum hoses
(3) VSV (for EGR) connector
(4) Throttle position sensor connector
(5) IAC valve connector
(6) (w/ TRAC)
Sub±throttle position sensor connector
(7) (w/ TRAC) Sub±throttle actuator connector
(8) (USA spec. only)
EGR gas temperature sensor connector
(b) Remove the four bolts and two nuts holding the intake air connector to the intake chamber.
(c) Remove the VSV nut.
(d) Disc onnect the two water by±pass hoses from the
throttle body. Plug the hose ends.
(e) Remove the throttle body with the intake air connector and gasket.
7. REMOVE NO. 3 TIMING BELT COVER AND CYLINDER
HEAD REAR COVER
(a) Remove the oil filler cap.
(b) Using a 5 mm hexagon wrench, remove the ten bolts,No. 3 timing belt cover and cylinder head rear cover.
8. DISCONNECT HIGH±TENSION CORDS FROM SPARK PLUGS
(a) Remove the bolt holding the cord clamp from thecylinder head.
(b) Disconnect the two high±tension cord clamps from the No. 3 cylinder head cover.
(c) Disconnect the high±tension cords at the rubber boot. Do not pull on the cords.
NOTICE: Pulling on or bending the cords may damage
the conductor inside.
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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.)
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13. REINSTALL NO. 3, NO. 1 AND NO. 2 CYLINDER HEADCOVERS
(a) Remove any oil packing (FIPG) material.
(b) Apply seal packing to the cylinder head as shown in theillustration.
Seal packing: Part No. 08826±00080 or equivalent
(c) Install the gaskets to the No. 1 and No. 2 cylinder headcovers.
(d) Install the cylinder head cover with the 12 bolts and four
nuts.
Torque: 5.4 N Vm (55 kgf Vcm, 48 in. Vlbf)
14. R E C O N N E C T H I G H ± T E N S I O N C O R D S TO S PA R K
PLUGS
(a) Connect the high±tension cord to the spark plug.
HINT: The No. 4 high±tension cord must be raised 10 5 from
the perpendicular line.
(b) Connect the two high±tension cord clamps to the No. 3 cylinder head cover.
(c) Install the high±tension cord clamp with the bolt.
15. REINSTALL CYLINDER HEAD REAR COVER AND NO. 3 TIMING BELT COVER
(a) Using a 5 mm hexagon wrench, install the cylinder head
rear cover and No. 3 timing belt cover with the ten bolts.
(b) Install the oil filler cap.
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19. REINSTALL AIR CLEANER HOSE(a) Install the air cleaner hose with two hose clamps.
(b) Connect the following hoses:(1) PS air hose to No. 4 timing belt cover
(2) PCV hose to No. 2 cylinder head cover
20. RECONNECT CONTROL CABLES TO THROTTLE BODY
Connect the following hoses:
(1) Accelerator cable
(2) (A/T) Throttle control cable
(3) Cruise control actuator cable
21. RE CO NNE CT CABLE TO NE G ATIV E TE RMINAL OF BATTERY
INSPECTION OF IGNITION TIMING
(See page IG±14)
Ignition timing:
105 BTDC @ idle
(w/ Terminals TE1 and E1 connected)
INSPECTION OF IDLE SPEED
HINT: Initial conditions (See step 1 on page EM±20)
Idle speed: M/T 700
+ 50 rpm
A/T 650
+ 50 rpm (N range)
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6. REMOVE UPPER HIGH±TENSION CORD COVER(a) Remove the two mounting bolts.
(b) Disconnect the front side claw groove of the cord coverfrom the claw of the lower cover, and remove the cord
cover.
7. REMOVE RH ENGINE WIRE COVER Remove the bolt and engine wire cover.
8. REMOVE LH ENGINE WIRE COVER Remove the two bolts and engine wire cover.
9. REMOVE VSV FOR EVAP SYSTEM Remove the two bolts, and disconnect the VSV from cylinder
head and timing belt cover.
10. REMOVE RH NO.3 TIMING BELT COVER Remove the three bolts and timing belt cover.
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11. DISCONNECT FUEL INLET HOSE FROM LH DELIVERYPIPE
Remove the pulsation damper and two gaskets, and discon-
nect the inlet hose.
12. D I S C O N N E C T F U E L R E T U R N H O S E F R O M F U E L RETURN PIPE
13. DISCONNECT PCV HOSE FROM LH CYLINDER HEAD
14. REMOVE LH NO.3 TIMING BELT COVER (a) Remove the four mounting bolts.
(b) Disconnect the cord grommet from the timing belt cover,
and remove the timing belt cover.
(c) Remove the cord grommet from the high±tension cord.
15. DISCONNECT HEATER WATER VALVE FROM BODY (a) Disconnect the VSV connector.
(b) Remove the bolt holding the engine wire clamp to thewater valve bracket.
(c) Remove the two bolts, and disconnect the water valve and bracket assembly.
16. REMOVE THROTTLE BODY (a) Disconnect the following connectors:(1) Throttle position sensor connector
(2) (w/ TRAC)
Sub±throttle position sensor connector
(3) (w/ TRAC) Sub±throttle actuator connector
(b) Disconnect the following hoses: (1) Water by±pass hose from ISC valve
(2) (USA Spec.) Vacuum hose from throttle body
(3) (Exc. USA Spec.) Three vacuum hoses from throttle body
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16. REMOVE LH CYLINDER HEAD COVER(a) Remove the two bolts holding the high±tension cordclamp to the cylinder head.
(b) Disc onnect the high±tension cords from the spark
plugs.
(c) Disconnect the high±tension cords from the front high±tension cord clamp.
(d) Disconnect the engine wire from the two wire clamps on
the LH delivery pipe.
(e) Disconnect the four injector connectors.
(f) Disconnect the two engine wire connectors.
(g) Remove the eight bolts, seal washers, cylinder head
cover and gasket.
19. SET NO.1 CYLINDER TO TDC/COMPRESSION (a) Turn the crankshaft pulley, and align its groove with thetiming mark º0º of the No.1 timing belt cover.
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