1991 LEXUS SC400 engine

EG21S±02
VALVE CLEARANCE INSPECTION AND
ADJUSTMENT
HINT: Inspect and adjust the valve clearance when the en-
gine is cold.
1. DISCONNECT NEGATIVE TERMINAL CABLE FROM BATTERY
CAUTION: Work must be started after 90 seconds from
the time the ignition switch is turned to the ªLOCKº posi-
tion and the negative (±) terminal cable is disconnected
from the battery.
2. DRAIN ENGINE COOLANT
3. REMOVE THROTTLE BODY COVER
(a) Disconnect the EVAP hose from the hose clamp.
(b) Remove the cap nut.
(c) Loosen the 2 bolts, and remove the hose clamp and throttle
body cover.
4. DISCONNECT CONTROL CABLES TO THROTTLE BODY Disconnect the following cables:
(1) Accelerator cable
(2) Transmission throttle control cable
(3) Cruise control actuator cable
5. REMOVE INTAKE AIR CONNECTOR
(a) Disconnect the following hoses: (1) Air hose from IAC valve
(2) Air hose (from air control valve on PS pump) from intake
air connector
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(b) Remove the bolt holding the intake air connector to thecylinder head cover.
(c) Remove the 2 hose clamps.
(d) Disconnect the intake air connector from the throttle body and air cleaner hose, and remove the intake air connector.
6. REMOVE UPPER HIGH±TENSION CORD COVER
(a) Remove the 2 bolts.
(b) Disconnect the front side claw groove of the upper cord cover
from the claw of lower cord cover, and remove the upper cord
cover.
7. REMOVE RH ENGINE WIRE COVER Remove the bolt and engine wire cover.
8. REMOVE LH ENGINE WIRE COVER Remove the 2 bolts and engine wire cover.
9. REMOVE VSV FOR EVAP SYSTEM Remove the 2 bolts, and disconnect the VSV from the cylin-
der head cover and timing belt cover.
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10. REMOVE RH NO.3 TIMING BELT COVERRemove the 3 bolts, timing belt cover and 3 gaskets.
11. DISCONNECT FUEL INLET HOSE FROM LH DELIVERY PIPE
Remove the pulsation damper and 2 gaskets, and discon-
nect the fuel inlet hose from the delivery pipe.
CAUTION:
w Put a shop towel under the delivery pipe.
w Slowly loosen the union bolt.
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 4 bolts.
(b) Disconnect the cord grommet from the timing belt cover, and remove the timing belt cover and 3 gaskets.
(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 the water valve bracket.
(c) Remove the 2 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
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(b) Disconnect the following hoses:(1) Water bypass hose from IAC valve
(2) California: Vacuum hose from throttle body
(3) Except California: 3 vacuum hoses from throttle body
(c) Remove the 2 bolts and 2 nuts, and disconnect the throttle body from the air intake chamber.
(d) Disconnect the following hoses, and remove the throttle body.
(1) PCV hose from throttle body
(2) Water bypass hose from throttle body
(e) Remove the throttle body gasket.
17. REMOVE RH CYLINDER HEAD COVER
(a) Disconnect the No.2 high±tension cord from the cord clamp on the front high±tension cord clamp.
(b) Remove the 2 bolts holding the high±tension cord clamps to the cylinder head cover.
(c) Disconnect the 5 high±tension cords from the front side of the
front high±tension cord clamp.
(d) Disconnect the front high±tension cord clamp from the lower high±tension cord cover.
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(e) Disconnect the 4 high±tension cords together with the frontand rear high±tension cord clamps from the spark plugs.
NOTICE: Pulling on or bending the cords may damage the con-
ductor inside.
(f) Remove the 8 bolts, seal washers, cylinder head cover and gasket.
18. REMOVE LH CYLINDER HEAD COVER
(a) Disconnect the No.1 high±tension cord from the cord clamp on the front high±tension cord clamp.
(b) Remove the 2 bolts holding the high±tension cord clamps to the cylinder head cover.
(c) Disconnect the 5 high±tension cords from the front side of the
front high±tension cord clamp.
(d) Disconnect the front high±tension cord clamp from the lower high±tension cord cover.
(e) Disconnect the 4 high±tension cords together with the front and rear high±tension cord clamps from the spark plugs.
NOTICE: Pulling on or bending the cords may damage the con-
ductor inside.
(f) Disconnect the engine wire protector from the 2 brackets on the delivery pipe.
(g) Disconnect the 4 injector connectors.
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(h) Disconnect the 2 engine wire connectors.
(i) Remove the 8 bolts, seal washers, cylinder head cover andgasket.
19. SET NO.1 CYLINDER TO TDC/COMPRESSION
(a) Turn the crankshaft pulley, and align its groove with timing mark ª0º of the No.1 timing belt cover.
(b) Check that the timing marks of the camshaft timing pulleys and timing belt rear plates aligned.
If not, turn the crankshaft 1 revolution (360 5) and align the
mark as above.
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20. INSPECT VALVE CLEARANCE
(a) Check only the valves indicated.wUsing a feeler gauge, measure the clearance between
the valve lifter and camshaft
w Record the out±of±specification valve clearance
measurements. They will be used later to determine the
required replacement adjusting shim.
Valve clearance (Cold):
Intake0.15 ± 0.25 mm (0.006 ± 0.010 in.)
Exhaust 0.25 ± 0.35 mm (0.010 ± 0.014 in.)
(b) Turn the crankshaft 1 revolution (360
) and align the mark as
above. (See procedure in step 8)
(c) Check only the valves indicated as shown. Measure the valve
clearance. (See procedure in step (a))
21. REMOVE THEFT DETERRENT HORN
(a) Disconnect the connector.
(b) Remove the bolt and theft deterrent horn. HINT: Remove the deterrent horn when the valve clearance
is adjusted for the front portion of the exhaust camshaft on
the LH cylinder head.
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22. ADJUST VALVE CLEARANCE
(a) Remove the adjusting shim.wTurn the crankshaft so that the cam lobe of the camshaft
on the adjusting valve upward.
w Position the hole of the adjusting shim facing the spark
plug side.
w Using SST (A), press down the valve lifter and place
SST (B) between the camshaft and valve lifter flange.
Remove SST (A).
SST 09248±05410, 09248±05021
NOTICE: The valve lifter is made of aluminum, which is easily
scratched. So when setting SST (B), take care not to scratch
the face of the valve lifter.
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