1991 LEXUS SC400 light

(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.
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ENGINE MECHANICAL Cylinder HeadsEM±83
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16. IF NECESSARY, REPLACE SPARK PLUG TUBEGASKETS
(a) Bend the ventilation case claw installed on the cylinderhead cover to an angle of 905 or more.
(b) Using SST and a hammer, tap out the gasket.
SST 09550±10012 (09552±10010, 09560±10010)
(c) Using SST and a hammer, tap in a new gasket until its surface is flush with the upper edge of the cylinder head
cover.
SST 09550±10012 (09552±10010, 09560±10010)
(d) Apply a light coat of MP grease to the gasket lip.
(e) Return the ventilation case claw to its original position.
ASSEMBLY OF CYLINDER HEADS
(See Components on page EM±59)
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 and oil seals with new ones.
1. INSTALL SPARK PLUG TUBES HINT: When using a new cylinder head, spark plug tubes
must be installed.
(a) Apply adhesive to the end of the spark plug tube.
Adhesive: Part No.08833±00070, THREE BOND 1324
or equivalent
(b) Using a wooden block and hammer, tap in a new sparkplug tube until there is 48.7±49.3 mm (1.917 ±1.941 in.)
protruding from the camshaft bearing cap installation
surface of the cylinder head.
NOTICE: Avoid tapping a new spark plug tube in too far
by measuring the amount of protrusion while tapping.
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ENGINE MECHANICAL Cylinder HeadsEM±89
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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 two
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 Check the valve lifter rotates smoothly by hand.
EM±90
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B. Install cylinder head boltsHINT:
wThe cylinder head bolts are tighten in two progressive
steps (steps (c) and (e)).
w If any one of the cylinder head bolts broken or deformed,
replace it.
(a) Apply a light coat of engine oil on the threads and under
the heads of the cylinder head bolts.
(b) Te mp o ra rily in sta ll th e twe n ty pla te wa sh e rs an d cylinder head bolts.
(c) Uniformly tighten the ten cylinder head bolts on one side
of the cylinder head in several passes in the sequence
shown, then do the other side as shown.
Torque: 39 N Vm (400 kgf Vcm, 29 ft Vlbf)
If any one of the bolts does not meet the torque specification,
replace the bolt.
(d) Mark the front of the cylinder head bolt head with paint.
(e) Retighten the cylinder head bolts 90 ° in the numerical
order shown.
(f) Check that the painted mark is now at a 90 ° angle to
front.
4. CONNECT MAIN OXYGEN SENSOR CONNECTORS Connect the RH and LH oxygen sensor connector.
5. INSTALL CIRCULAR PLUGS (a) Place two new circular plugs in position on the cylinderheads, facing the cup side forward.
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ENGINE MECHANICAL Cylinder HeadsEM±93
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(b) Remove any old packing (FIPG) material.
(c) Apply seal packing to the bearing caps as shown.
Seal packing: Part No. 08826±00080 or equivalent
(d) (RH Cylinder Head)Install the bearing cap (mark ºI1º) in position with the ar-
row mark facing rearward.
(e) (LH Cylinder Head) Install the bearing cap (mark ºI6º) in position with the ar-
row mark facing forward.
(f) Install a new seal washer to the bearing cap bolt.
(g) Apply a light of engine oil on the threads of the bearing
cap bolt.
(h) Install the four bearing cap bolts.
Torque: 16 N Vm (160 kgf Vcm, 12 ft Vlbf)
HINT: Use silver colored bolts 38 mm (1.50 in.) in length.
6. ASSEMBLE EXHAUST CAMSHAFTS (a) Install the following parts:(1) Camshaft gear spring
(2) Camshaft sub±gear
(3) Wave washer
(b) Using snap ring pliers, install the snap ring.
(c) M ount the hexagon wrench head portion of the
camshaft in a vice.
EM±94
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ENGINE MECHANICAL Cylinder Heads
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(f) Install the other bearing caps in the sequence shownwith the arrow mark facing rearward.
HINT: Align the arrow marks at front and rear of the cylinder
head with the mark on the bearing cap.
(g) Apply a light coat of engine oil on the threads and under
the heads (A only) of the bearing cap bolts.
HINT: Do not apply engine oil under the heads of the bearing
cap bolts (B).
(h) Install a new seal washer to the bearing cap bolt (B).
Install the eight bearing cap bolts as shown.
HINT:
w Use bearing cap bolts 38 mm (1.50 in.) in length. The
bolts are black (A) or silver (B) in color. Install the two
silver bolts to the front bearing cap. Install the six black
bolts to the other positions.
w After installing the oil feed pipe, install the two bolts to
the rear bearing cap as directed in step B (i).
(i) Uniformly tighten the eight bearing cap bolts in several passes in the sequence shown.
Torque: 16 N Vm (160 kgf Vcm, 12 ft Vlbf)
B. Install exhaust camshaft to RH cylinder head
(a) Set the timing mark ( one dot mark) of the camshaft drive
gear at 105 angle by turning the hexagon wrench head
portion of the intake camshaft with a wrench.
(b) Apply MP grease to the thrust portion of the exhaust camshaft.
(c) Align the timing marks (one dot mark) of the camshaft
drive and driven gears.
(d) Place the exhaust camshaft on the cylinder head.
EM±96
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ENGINE MECHANICAL Cylinder Heads
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(e) Check that the exhaust camshaft moves smoothly in the
thrust direction.
(f) Install the rear bearing cap with the arrow mark facing rearward.
HINT:
w Installing the rear bearing cap will determine the thrust
position of the camshaft.
w Align the arrow marks at front and rear of the cylinder
head with the mark on the bearing cap.
(g) Install the other bearing caps in the sequence shown with the arrow mark facing rearward.
HINT: Align the arrow marks at front and rear of the cylinder
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 ten 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 pipe. Install the eight 38 mm (1.50 in.) bolts in the other
positions.
(j) Uniformly tighten the eight bearing cap 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)
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ENGINE MECHANICAL Cylinder HeadsEM±97
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(f) Install the other bearing caps in the sequence shownwith the arrow mark facing forward.
HINT: Align the arrow marks at front and rear of the cylinder
head with the mark on the bearing cap.
(g) Apply a light coat of engine oil on the threads and under
the heads (A only) of the bearing cap bolts.
HINT: Do not apply engine oil under the heads of the bearing
cap bolts (B).
(h) Install a new seal washer to the bearing cap bolt (B).
Install the eight bearing cap bolts as shown.
HINT:
w Use bearing cap bolts 38 mm (1.50 in.) in length. The
bolts are black (A) or silver (B) in color. Install the two
silver bolts to the front bearing cap. Install the six black
bolts to the other positions.
w After installing the oil feed pipe, install the two bolts to
the bearing cap second from the front as directed in step
D (i).
(i) Uniformly tighten the eight bearing cap bolts in several passes in the sequence shown.
Torque: 16 N Vm (160 kgf Vcm, 12 ft Vlbf)
D. Install exhaust camshaft to LH cylinder head
(a) Set the timing mark (two dot marks) of the camshaftdrive gear at 15 ° angle by turning the hexagon wrench
head portion of the intake camshaft with a wrench.
(b) Apply MP grease to the thrust portion of the exhaust camshaft.
(c) Align the timing marks (two dot marks) of the camshaft
drive and driven gears.
(d) Place the exhaust camshaft on the cylinder head.
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ENGINE MECHANICAL Cylinder HeadsEM±99
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