LEXUS SC400 1991 Service Repair Manual

H. Inspect camshaft gear backlash
(a) Install the camshafts without installing the exhaust camsub±gear.
(See step 7 on pages EG±114 to 120)
(b) Using a dial indicator, measure the backlash.
Standard backlash:
0.020 ± 0.200 mm (0.0008 ± 0.0079 in.)
Maximum backlash: 0.30 mm (0.0188 in.)
If the backlash is greater then maximum, replace the cam-
shafts.
(c) Remove the camshafts.
11. INSPECT VALVE LIFTERS AND LIFTER BORES
(a) Using a caliper gauge, measure the ufter bore diameter of the
clinder head.
Lifter bore diameter:
31.000±31.016 mm (1.2205±1.2211 in.)
(b) Using a micrometer, measure the lifter diameter.
Lifter diameter:30.966 ± 30.976 mm (1.2191 ± 1.2195 in.)
(c) Subtract the lifter diameter measurement from the lifter borediameter measurement.
Standard oil clearance:
0.024 ± 0.050 mm (0.0009 ± 0.0020 in.)
Maximum oil clearance: 0.07 mm (0.0028 in.)
If the oil clearance is greater than maximum, replace the lifter.
If necessary, replace the cylinder head.
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12. INSPECT AIR INTAKE CHAMBERUsing a precision straight edge and feeler gauge, measure
the surface contacting the intake manifold for warpage.
Maximum warpage:
0.15 mm (0.0059 in.)
If warpage is greater than maximum, replace the chamber.
13. INSPECT INTAKE MANIFOLD Using a precision straight edge and feeler gauge, measure
the surface contacting the cylinder head and air intake cham-
ber for warpage.
Maximum warpage:
0.15 mm (0.0059 in.)
If warpage is greater than maximum, replace the manifold.
14. INSPECT EXHAUST MANIFOLD Using a precision straight edge and feeler gauge, measure
the surface contacting the cylinder head for warpage.
Maximum warpage:
1.00 mm (0.0394 in.)
If warpage is greater than maximum, replace the manifold.
15. INSPECT CYLINDER HEAD BOLTS Using a caliper gauge, measure the thread outside diameter
of the bolt.
Standard outside diameter:
9.770 ± 9.960 mm (0.3846 ± 0.3921 in.)
Maximum outside diameter: 9.60 mm (0.3780 in.)
If the diameter is less than minimum, replace the bolt.
EG±106
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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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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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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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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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(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
EG±112±
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(d) RH Cylinder Head:Install the bearing cap (mark ª11º) in position with the arrow
mark facing rearward.
(e) LH Cylinder Head: Install the bearing cap (mark ª16º) in position with the arrow
mark facing forward.
(f) Install a new seal washer to the bearing cap bolt.
(g) Apply a light coat of engine oil on the threads of the bearing
cap bolt.
(h) Install the 4 bearing cap bolts. Alternately tighten 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 CAMSHAFT
(a) Install the following parts: (1) Camshaft gear spring
(2) Camshaft sub±gear
(3) Wave washer
HINT: Align the pins on the gears with the spring ends.
(b) Using snap ring pliers, install the snap ring.
(c) Mount the hexagon wrench head portion of the camshaft in a vise.
NOTICE: Be careful not to damage the camshaft.
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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.
EG±114
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