1991 LEXUS SC400 sensor

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.
EG±92
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(b) Remove the main heated oxygen sensor.
(c) Remove the 8 nuts, exhaust manifold and gasket.
EG11C±06
CYLINDER HEAD DISASSEMBLY
(See Components for Removal and Installation)
1. REMOVE VALVE LIFTERS AND SHIMSHINT: Arrange the valve lifters and shims in correct order.
2. REMOVE VALVES
(a) Using SST, compress the valve spring and remove the 2 keepers.
SST 09202±70010
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CYLINDER HEADS INSTALLATION
EG22V±02
(See Components for Removal and Installation)
1. INSTALL RH EXHAUST MANIFOLD TO RH CYLINDERHEAD
(a) Place a new gasket on the cylinder head with the white painted marks facing the manifold side.
NOTICE: Be careful of the Installation direction.
(b) Install the ex haust manifold with 8 new nuts. Uniformly
tighten 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.
2. INSTALL LH EXHAUST MANIFOLD TO LH CYLINDER
HEAD
(a) Place a new gasket on the cylinder head with the white
painted marks facing the manifold side.
NOTICE: Be careful of the installation direction.
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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.
EG±110
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(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 HEATED OXYGEN SENSOR CONNECTORS
Connect the RH and LH oxygen sensor connectors.
5. INSTALL CIRCULAR PLUGS
(a) Place 2 new circular plugs in position on the cylinder heads, facing the cup side forward.
(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
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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.
EG±124
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(l) Install the accelerator bracket with the bolt and stud bolt.
(m) Install 2 new gaskets and union with the union bolt.
Torque: 29 NVm (300 kgf Vcm, 22 ft Vlbf)
(n) Connect the following hoses:
(1) Brake booster vacuum hose to union on air intake cham-
ber
(2) Vacuum hose (from VSV for heater water valve to air in-
take chamber
29. INSTALL THROTTLE BODY
(a) Disconnect the following hoses: (1) PCV hose to throttle body
(2) Water bypass hose to throttle body
(b) Install a new gasket and throttle body with the 2 bolts and 2 nuts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
HINT: Use bolt 40 mm (1.57 in.) in length.
(c) Install the water bypass pipe (from the rear bypass joint) to the clamp on the engine wire cover.
(d) Connect 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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