1991 LEXUS SC400 check engine light

(b) Connect the tester probe of a timing light to the high ±tension
cord for No.6 cylinder.
(c) Using a timing light, check the ignition timing.
Ignition timing: 8 ± 12 5 BTDC @ idle
(Transmission in neutral position)
If the ignition timing is not as specified, check that following
conditions are normal:
w Throttle valve fully closed
w Continuity between terminals IDL1 and E2 of the throttle
position sensor
w Valve timing
(d) Remove the SST from the DLC1. SST 09843±18020
5. DISCONNECT TACHOMETER AND TIMING LIGHT FROM ENGINE
6. REINSTALL UPPER HIGH±TENSION CORD COVER
(a) Fit portion A of the upper high±tension cord cover matching the top of the lower high±tension cord cover.
(b) Push the front side of the upper high±tension cord cover, and
fit the front side claw groove of the upper high±tension cord
cover to the claw of the lower high ±tension cord cover.
(c) Install the upper high±tension cord cover with the 2 bolts.
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(d) Using SST, align the timing marks of the LH camshaft timingpulley and timing belt rear plate.
SST 09278±54012
(e) C h e c k t h a t t h e t i m i n g b e l t h a s t e n s i o n b e t w e e n t h e
crankshaft timing pulley and LH camshaft timing pulley.
14. CONNECT TIMING BELT TO RH CAMSHAFT TIMING PULLEY
(a) Remove any oil or water on the RH camshaft timing pulley
and water pump pulley, and keep them clean.
(b) Using SST, slightly turn the RH camshaft timing pulley clockwise. Align the installation mark on the timing belt with
the timing mark of the camshaft timing pulley, and hang the
timing belt on the RH camshaft timing pulley.
SST 09278±54012
(c) Using SST, align the timing marks of the RH camshaft timing pulley and timing belt rear plate.
SST 09278±54012
(d) Check that the timing belt has tension between the RH camshaft timing pulley and LH camshaft timing pulley.
15. SET TIMING BELT TENSIONER
(a) Using a press, slowly press in the push rod using 981 ± 9,807
N (100 ± 1,000 kgf, 220 ± 2,205 lbf) of force.
(b) Align the holes of the push rod and housing, pass a 1.27 mm hexagon wrench through the holes to keep the setting
position of the push rod.
(c) Release the press.
(d) Install the dust boot to the belt tensioner.
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(d) Check the valve overall length.
Standard overall length:Intake94.95 mm (3.7382 in.)
Exhaust 96.90 mm (3.8150 in.)
Minimum overall length:
Intake94.45 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 minimum.
8. INSPECT AND CLEAN VALVE SEATS
(a) Using a 45
carbide cutter, resurface the valve seats.
Remove only enough metal to clean the seats.
(b) Check the valve seating position. Apply a light coat of prussian blue (or white lead) to the valve
face. Lightly press the valve against the seat. Do not rotate
valve.
(c) Check the valve face and seat for the following: wIf blue appears 360
around the face, the valve is
concentric. If not, replace the valve.
w If blue appears 360
around the valve seat, the guide
and face are concentric. If not, resurface the seat.
w Check that the seat contact is in 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.
EG±100
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2. INSTALL VALVES
(a) Using SST, push in a new oil seal.SST 09201±41020
(b) Install the following parts: (1) Valve
(2) Spring seat
(3) Valve spring
(4) Spring retainer
(c) Using SST, compress the valve spring and place the 2 keepers around the valve stem.
SST 09202±70010
(d) Using a plastic±faced hammer, lightly tap the valve stem tip to assure proper fit.
3. INSTALL VALVE LIFTERS AND SHIMS
(a) Install the valve lifter and shim.
(b) Check that the valve lifter rotates smoothly by hand.
EG±108
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(b) Apply MP grease to the thrust portion of the exhaustcamshaft.
(c) Align the timing marks (1 dot mark) of the camshaft drive and
driven gears.
(d) Place the exhaust camshaft on the cylinder head.
(e) Check that the exhaust camshaft moves smoothly in the thrust direction.
(f) Install the rear bearing cap (mark ªE1º) with the arrow mark facing rearward.
HINT:
wInstalling the rear bearing cap will determine the thrust
portion of the camshaft.
w Align the allow marks at the front and rear of the cylinder
head with the mark on the bearing cap.
(g) Install the other 3 bearing caps in the sequence shown with the arrow marks facing rearward.
HINT: Align the arrow marks at the front and rear of the cylin-
der head with the mark on the bearing cap.
(h) Apply a light coat of engine oil on the threads and under the heads of the bearing cap bolts.
(i) Install the oil feed pipe and 10 bolts.
HINT: Use bearing cap bolts 38 mm (1.50 in.) and 52 mm
(2.05 in.) in length. Use black colored 38 mm (1.50 in.) bolts.
Install the two 52 mm (2.05 in.) bolts in outside positions of
the oil feed pipe. Install the eight 38 mm (1.50 in.) bolts in the
other positions.
EG±116
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(h) Apply a light coat of engine oil on the threads and under theheads of the bearing cap bolts.
(i) Install the oil feed pipe and 10 bolts.
HINT: Use bearing cap bolts 38 mm (1.50 in.) and 52 mm
(2.05 in.) in length. Use black colored 38 mm (1.50 in.) bolts.
Install the two 52 mm (2.05 in.) bolts in outside positions of
the oil feed pipe. Install the eight 38 mm (1.50 in.) bolts in the
other positions.
(j) Uniformly tighten the 8 bolts on the bearing caps of the exhaust camshaft in several passes, in the sequence shown.
Torque: 16 N Vm (160 kgf Vcm, 12 ft Vlbf)
(k) Alternately ti ghten the 2 bolts on the bearing cap of the intake
camshaft 2nd from the front in several passes.
Torque: 16 N Vm (160 kgf Vcm, 12 ft Vlbf)
(l) Boring the service bolt installed in the driven subgear upward
by turning the hexagon wrench head portion of the camshaft
with a wrench.
(m) Remove the service bolt.
8. CHECK AND ADJUST VALVE CLEARANCE (See steps 19 to 22 on pages EG±19 to 21)
Turn the camshaft and position the cam lobe upward, and
check and adjust the valve clearance.
Valve clearance (Cold):
Intake0.15 ± 0.25 mm (0.006 ± 0.010 in.)
Exhaust 0.25 ± 0.35 mm (0.010 ± 0.014 in.)
EG±120±
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7. IF NECESSARY, REPLACE MAIN BEARING CAP STUDBOLTS
(a) Using the 2 main bearing cap nuts, remove the stud bolt.
(b) Apply a light coat of engine oil on the threads and under
flange of new stud bolts.
(c) Using the 2 main bearing cap nuts, install the stud bolt.
Torque: 15 N Vm (150 kgf Vcm, 11 ft Vlbf)
HINT: Stud bolts come in lengths of 90.0 mm (3.543 in.) and
101.5 mm (3.996 in.). Install the 101.5 mm (3.996 in.) bolts
in inside positions. Install the 90.0 mm (3.543 in.) bolts in out-
side positions.
PISTON AND CONNECTING ROD
DISASSEMBLY
EG0BV±06
1. CHECK FIT BETWEEN PISTON AND PISTON PIN
Try to move the piston back and forth on the piston pin.
If any movement is felt, replace the piston and pin as a set.
2. REMOVE PISTON RINGS
(a) Using a piston ring expander, remove the 2 compression rings.
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(a) Apply a light coat of engine oil on the threads and under themain bearing cap nuts.
(b) Install and uniformly tighten the 20 main bearing cap nuts in
several passes, in the sequence shown.
Torque: 27 N Vm (275 kgf Vcm, 20 ft Vlbf)
If any one of the main bearing cap nuts does not meet the
torque specification, replace the main bearing cap stud bolt.
(c) Mark the front of the main bearing cap nut with paint.
(d) Retighten the main bearing cap bolts 90
in the numerical
order shown.
(e) Check that the painted mark is now at a 90
angle to the front.
C. Install main bearing cap bolts
(a) Install a new seal washer to the main bearing cap bolt.
(b) Install and uniformly tighten the 10 main bearing cap bolts.
Torque: 49 N Vm (500 kgf Vcm, 36 ft Vlbf)
(c) Check that the crankshaft turns smoothly.
5. CHECK CRANKSHAFT THRUST CLEARANCE
Using a dial indi cator, measure the thrust clearance while pry-
ing the crankshaft back and forth with a screwdriver.
Standard thrust clearance:
0.020 ± 0.220 mm (0.0008 ± 0.0087 in.)
Maximum thrust clearance: 0.30 mm (0.0118 in.)
If the thrust clearance is greater than maximum, replace the
thrust washers as a set.
Thrust washer thickness:2.440 ± 2.490 mm (0.0961 ± 0.0980 in.)
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