lock LEXUS SC400 1991 Service Repair Manual

40. DISCONNECT MAIN HEATED OXYGEN SENSORCONNECTORS
Disconnect the RH and LH oxygen sensor connectors.
41. REMOVE CYLINDER HEADS
(a) Uniformly loosen the ten cylinder head bolts one side of each
cylinder head in several passes, in the sequence shown,
then do the other side as shown. Remove the 20 cylinder
head bolts and plate washers.
NOTICE:
w Cylinder head warpage or cracking could result from
removing bolts in incorrect order.
w Do not drop the plate washer for cylinder head bolt into
portion A of the cylinder head. If dropped into portion A,
the plate washer will pass through the cylinder head and
cylinder block into the oil pan.
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(b) Lift the cylinder head from the dowels on the cylinder block,and place the 2 cylinder heads on wooden blocks on a bench.
HINT: If the cylinder head is off, pry between the cylinder
head and cylinder block with a screwdriver.
NOTICE: Be careful not to damage the contact surfaces of the
cylinder head and cylinder block.
42. REMOVE EXHAUST MANIFOLD FROM RH CYLINDERHEAD
(a) Remove the 3 bolts and heat insulator.
(b) Remove the main heated oxygen sensor.
(c) Remove the 8 nuts, exhaust manifold and gasket.
43. REMOVE EXHAUST MANIFOLD FROM LH CYLINDER
HEAD
(a) Remove the 3 bolts and heat insulator.
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EG1KM±02
CYLINDER HEAD COMPONENTS
INSPECTION AND REPAIR
1. CLEAN TOP SURFACES OF PISTONS AND CYLINDERBLOCK
(a) Turn the crankshaft, and bring each piston to top dead center (TDC). Using a gasket scraper, remove all the carbon from
the piston top surface.
(b) Using a gasket scraper, remove all the gasket material from the cylinder block surface.
(c) Using compressed air, blow carbon and oil from the bolt
holes.
CAUTION: Protect your eyes when using high±compressed
air.
2. CLEAN CYLINDER HEAD
A. Remove gasket materialUsing a gasket scraper, remove all the gasket material from
the cylinder block contact surface.
NOTICE: Be careful not to scratch the cylinder block contact
surface.
B. Clean combustion chambers
Using a wire brush, remove all the carbon from the combus-
tion chambers.
NOTICE: Be careful not to scracth the cylinder block contact
surface.
C. Clean valve guide bushingsUsing a valve guide bushing brush and solvent, clean all the
guide bushings.
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D. Clean cylinder headUsing a soft brush and solvent, thoroughly clean the cylinder
head.
3. INSPECT CYLINDER HEAD
A. Inspect for flatness Using a precision straight edge and feeler gauge, measure
the surface contacting the cylinder block and the manifolds
for warpage.
Maximum warpage:
0.10 mm (0.0039 in.)
If warpage is greater than maximum, replace the cylinder
head.
B. Inspect for cracks Using a dye penetrant, check the combustion chamber, in-
take ports, exhaust ports and cylinder block surface for
cracks.
If cracked, replace the cylinder head.
4. CLEAN VALVES
(a) Using a gasket scraper, chip off any carbon from the valve head.
(b) Using a wire brush, thoroughly clean the valve.
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10. INSPECT CAMSHAFTS AND BEARINGS
A. Inspect camshaft for runout
(a) Place the camshaft on V±blocks.
(b) Using a dial indicator, measure the circle runout at the centerjournal.
Maximum circle runout:
0.08 mm (0.0031 in.)
If the circle runout is greater than maximum, replace the cam-
shaft.
B. Inspect cam lobes Using a micrometer, measure the cam lobe height.
Standard cam lobe height:
Intake41.710 ± 41.810 mm (1.6421 ± 1.6461 in.)
Exhaust 41.910 ± 42.010 mm (1.6500 ± 1.6539 in.)
Minimum cam lobe height: Intake41.56 mm (1.6362 in.)
Exhaust
41.76 mm (1.6441 in.)
If the cam lobe height is less than minimum, replace the cam-
shaft.
C. Inspect camshaft journals Using a micrometer, measure the journal diameter.
Journal diameter:
Exhaust camshaft thrust portion (A)23.959 ± 23.975 mm (0.9433 ± 0.9439 in.)
Others 26.954 ± 26.970 mm (1.0612 ± 1.0618 in.)
If the journal diameter is not as specified, check the oil clear-
ance.
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16. IF NECESSARY, REPLACE SPARK PLUG TUBEGASKETS
(a) Bend the ventilation case claw installed on the cylinder head
cover to an angle of 90
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.
CYLINDER HEAD ASSEMBLY
EG1KN±02
(See Components for Removal and Installation) HINT:
wThoroughly 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 spark tubeuntil there is 48.7 ± 49.3 mm (1.917 ± 1.941) 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 the protrusion while tap-
ping.
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(b) Install the exhaust manifold with 8 new nuts. Uniformlytighten the nuts in several passes.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
(c) Install the main heated oxygen sensor.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
(d) Install the heat insulator with the 3 bolts.
3. INSTALL CYLINDER HEADS
A. Place cylinder head on cylinder block
(a) Place 2 new cylinder head gaskets in position on the cylinder
block.
HINT: On the rear side of the cylinder head gasket are
painted marks to distinguish the LH and RH banks, a white
painted mark for the RH bank and a yellow painted mark for
the LH bank.
NOTICE: Be careful of the installation direction.
(b) Place the 2 cylinder heads in position on the cylinder headgaskets.
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B. Install cylinder head boltsHINT:
wThe cylinder head bolts are tightened in 2 progressive
steps (steps (c) and (e)).
w If any cylinder head bolt is 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) Install the plate washer to the cylinder head bolt.
(c) Install and uniformly tig hten the 10 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 cylinder head bolts does not meet the torque
specification, replace the cylinder head bolt.
NOTICE: Do not drop the plate washer for cylinder head bolt
into portion A of the cylinder head. If dropped into portion A,
the plate washer will pass through the cylinder head and cylin-
der block into the oil pan.
(d) Mark the front of the cylinder head bolt head with paint.
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(d) Insert service bolt A into the service hole of the camshaftsub±gear.
(e) Using a screwdriver, align the holes of the camshaft drive
gear and sub±gear by turning camshaft subgear clockwise,
and temporarily install service bolt B.
NOTICE: Be careful not to damage the camshaft.
(f) Align the gear teeth of the drive gear and sub±gear, and
tighten service bolt B.
7. INSTALL CAMSHAFTS
NOTICE: Since the thrust clearance of the camshaft is small,
the camshaft must be kept level while it is being installed. If the
camshaft is not kept level, the portion of the cylinder head re-
ceiving the shaft thrust may crack or be damaged, causing the
camshaft to seize or break. To avoid this, the following steps
should be carried out.
A. Install intake camshaft to RH cylinder head
(a) Apply MP grease to the thrust portion of the intake camshaft.
(b) Place the intake camshaft at 45
angle of the timing mark (1
dot mark) on the cylinder head.
(c) Remove any old packing (FIPG) material.
(d) Apply seal packing to the bearing cap (mark ª16º) as shown.
Seal packing: Part No. 08826±00080 or equivalent
(e) Install the front bearing cap (mark ª16º) with the arrow markfacing rearward.
HINT:
wInstalling the front 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.
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(b) Install the engine wire protector with the bolt.
(c) Connect the following connectors:(1) ECT sensor connector
(2) ECT sender gauge connector
19. INSTALL INTAKE MANIFOLD
(a) Place 2 new gaskets on the cylinder heads with white painted
mark facing upward.
NOTICE: Align the port holes of the gasket and cylinder head.
Be careful of the installation direction.
(b) Place the intake manifold on the cylinder heads with the
arrow mark facing forward.
NOTICE: Be careful of the installation direction.
(c) Install and uniformly tighten the 6 bolts and 4 nuts in severalpasses.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
HINT: Use bolt 30 mm (1.18 in.) in length.
20. INSTALL INJECTORS AND DELIVERY PIPE
(a) Install a new grommet to the injector.
(b) Apply a light coat of gasoline to a new O±ring, and install it to the injector.
(c) While turning the injector clockwise and counterclockwise, push it to the delivery pipe. Install the 8 injectors.
(d) Position the injector connector outward.
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