ect LEXUS SC300 1991 Service Repair Manual

D. Inspect camshaft bearingsCheck that bearings for flaking and scoring.
If the bearings are damaged, replace the bearing caps and
cylinder head a set.
E. Inspect camshaft gear spring Using a vernier caliper measure the free distance between
the spring ends.
Free distance:
18.2 ± 18.8 mm (0.712 ± 0.740 in.)
If the free distance is not as specified, replace the gear
spring.
F. Inspect camshaft journal oil clearance
(a) Clean the bearing caps and camshaft journals.
(b) Place the camshafts on the cylinder head.
(c) Lay a strip of Plasti gage across each of the camshaft
journals.
(d) Install the bearing caps. (See step 7 on pages EG±114 to 120)
Torque: 16 N Vm (160 kgf Vcm, 12 ft Vlbf)
NOTICE: Do not turn the camshaft.
(e) Remove the bearing caps.
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(f) Measure the Plastigage at its widest point.
Standard oil clearance:Exhaust camshaft thrust portion
0.025 ± 0.061 mm (0.0010 ± 0.0024 in.)
Others 0.030 ± 0.067 mm (0.0012 ± 0.0026 in.)
Maximum oil clearance: 0.10 mm (0.0039 in.)
If the oil clearance is greater than maximum, replace the cam-
shaft. If necessary, replace the bearing caps and cylinder
head as a set.
(g) Completely remove the Plastigage.
(h) Remove the camshafts.
G. Inspect camshaft thrust clearance
(a) Install the camshaft. (See step 7 on pages EG±114 to 120)
(b) Using a dial indicator, measure the thrust clearance while moving the camshaft back and forth.
Standard thrust clearance:
0.040 ± 0.090 mm (0.0016 ± 0.0035 in.)
Maximum thrust clearance: 0.12 mm (0.0047 in.)
If the thrust clearance is greater than maximum, replace the
camshaft. If necessary, replace the bearing caps and cylin-
der head as a set.
(c) Remove the camshafts.
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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.
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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.
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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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(f) Install the other 4 bearing caps in the sequence shown withthe 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.
(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 bolt (B).
(h) Install a new seal washer to the bearing cap bolt (B). Install the 8 bearing cap bolts as shown.
HINT:
wUse bearing cap bolts 38 mm (1.50 in.) in length. The
bolts are black (A) or silver (B) in color. Install the 2 silver
bolts to the front bearing cap. Install the 6 black bolts to
the other positions.
w After installing the oil feed pipe, install the 2 bolts to rear
bearing cap as directed in step B (i).
(i) Uniformly tighten the 8 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 (1 dot mark) of the camshaft drive gear
at 10
angle by turning the hexagon wrench head portion of
the intake camshaft with a wrench.
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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.
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(e) Install the front bearing cap (mark ª11º) with the arrow markfacing forward.
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.
(f) Install the other 4 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.
(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 bolt (B).
(h) Install a new seal washer to the bearing cap bolt (B). Install the 8 bearing cap bolts as shown.
HINT:
wUse bearing cap bolts 38 mm (1.50 in.) in length. The
bolts are black (A) or silver (B) in color. Install the 2 silver
bolts to the front bearing cap. Install the 6 black bolts to
the other positions.
w After installing the oil feed pipe, install the 2 bolts to the
bearing cap 2nd from the front as directed in step B (i).
(i) Uniformly tighten the 8 bearing cap bolts in several passes, in the sequence shown.
Torque: 16 N Vm (160 kgf Vcm, 12 ft Vlbf)
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