lock LEXUS SC400 1991 Service Repair Manual

(d) Using a plastic±faced hammer, lightly tap the valve stem
tip to assure proper fit.
4. INSTALL VALVE LIFTERS AND SHIMS (a) Install the valve lifter and shim.
(b) Check that the valve lifter rotates smoothly by hand.
INSTALLATION OF CYLINDER HEAD
(See Components on pages EM±34 and 35)1. INSTALL CYLINDER HEAD
A. Place cylinder head on cylinder block (a) Place a new cylinder head gasket in position on thecylinder block.
NOTICE: Be sure to install it correctly.
(b) Place the cylinder head in position on the cylinder head
gasket and connect the heater water hose to the union.
B. Install cylinder head bolts
HINT:
wThe cylinder head bolts are tightened in two progressive
steps (steps (c) and (f)).
w If any of bolts break or deform, replace them.
(a) Apply a light coat of engine oil on the threads and under
the heads of the cylinder head bolts.
(b) Install the 14 plate washers to each cylinder head bolt.
(c) First, using a 10 mm bi±hexagon wrench, uniformly tighten the cylinder head bolts in several passes in the
sequence shown.
Torque: 34 N Vm (350 kgf Vcm, 25 ft Vlbf)
If any one of the bolts does not meet the torque specification,
replace the bolt.
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(c) Uniformly loosen and remove the eight bearing capbolts in several passes in the sequence shown.
(d) Remove the four bearing caps, oil seal and intake camshaft.
HINT: Arrange the bearing caps in correct order.
42. DISASSEMBLE EXHAUST CAMSHAFTS (a) M ount the hexagon wrench head portion of the
camshaft in a vise.
NOTICE: Be careful not to damage the camshaft.
(b) Insert a service bolt (A) into the service hole of the camshaft sub±gear.
(c) Using a screwdriver, turn the sub±gear clockwise, and
remove the service bolt (B).
NOTICE: Be careful not to damage the camshaft.
(d) Using snap ring pliers, remove the snap ring.
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45. REMOVE CYLINDER HEADS(a) Uniformly loosen the ten cylinder head bolts on one side
of each cylinder head in several passes in the sequence
shown, then do the other side as shown. Remove the
twenty cylinder head bolts and plate washers.
NOTICE: Head warpage or cracking could result from re-
moving bolts in an incorrect order.
(b) Lift the cylinder heads from the dowels on the cylinder block, and place the two cylinder heads on wooden
blocks on a bench.
HINT: If the cylinder head is difficult to lift 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.
46. REMOVE EXHAUST MANIFOLD FROM RH CYLINDER HEAD
(a) Remove the three bolts and heat insulator.
(b) Remove the main oxygen sensor.
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ENGINE MECHANICAL Cylinder HeadsEM±75
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INSPECTION, CLEANING AND REPAIR
OF CYLINDER HEAD COMPONENTS
1. CLEAN TOP SURFACES OF PISTONS AND CYLINDERBLOCK
(a) Turn the crankshaft and bring each piston to top deadcenter (TDC). Using a gasket scraper, remove all the
carbon from the piston top surfaces.
(b) Using a gasket scraper, remove all the gasket material from the top surfaces of the cylinder block.
(c) Using compressed air, blow carbon and oil from the bolt
holes.
CAUTION: Protect your eyes when using high±pressure
compressed air.
2. CLEAN CYLINDER HEADS
A. Remove gasket material Using a gasket scraper, remove all the gasket material from the cylinder block surface.
NOTICE: Be careful not to scratch the cylinder block con-
tact surface.
B. Clean combustion chambers Using a wire brush, remove all the carbon from the combus-
tion chambers.
NOTICE: Be careful not to scratch the cylinder block con-
tact surface.
C. Clean valve guide bushings Using a valve guide bushing brush and solvent, clean all the
guide bushings.
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D. Clean cylinder headsUsing a soft brush and solvent, thoroughly clean the cylinder
heads.
3. INSPECT CYLINDER HEADS
A. Inspect for flatness Using a precision straight edge and feeler gauge, measure
the surfaces contacting the cylinder block and 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 any carbon from the valvehead.
(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 thecenter journal.
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:
Intake 41.710±41.810 mm (1.6421±1.6461 in.)
Exhaust 41.910±42.010 mm (1.6500±1.6539 in.)
Minimum cam lobe height: Intake 41.56 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.
D. Inspect camshaft bearings Check the bearings for flaking and scoring.
If the bearings are damaged, replace the bearing caps and
cylinder head as a set.
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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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(b) Install the exhaust manifold with the eight new nuts.Uniformly tighten the nuts in several passes.
Torque: 39 N Vm (400 kgf Vcm, 29 ft Vlbf)
(c) Install the main oxygen sensor.
Torque: 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
(d) Install the heat insulator with the three bolts.
3. INSTALL CYLINDER HEADS
A. Place cylinder heads on cylinder block (a) Place two new cylinder head gaskets in position on thecylinder 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 two cylinder heads in position on the cylinder
head gaskets.
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(d) Insert a service bolt (A) into the service hole of thecamshaft sub±gear.
(e) Using a screwdriver, align the service holes and teeth of the camshaft driven gear and sub±gear by turning
camshaft sub±gear clockwise, and install a service bolt
(B).
NOTICE: Be careful not to damage the camshaft.
(f) Remove the service bolt (A).
7. INSTALL CAMSHAFTS NOTICE: Since the thrust clearance of the camshaft is
small, the camshaft must be held level while it is being
installed. If the camshaft is not kept level, the portion of
the cylinder head receiving 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 camshaft.
(b) Place the intake camshaft at 45 ° angle of the timing
mark (one dot mark) on the cylinder head.
(c) Remove any old packing (FIPG) material.
(d) Apply seal packing to the bearing cap (mark ºI6º) as shown.
Seal packing: Part No. 08826±00080 or equivalent
(e) Install the front bearing cap (mark ºI6º) with the arrow mark facing rearward.
HINT:
w Installing the front 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.
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22. INSTALL DELIVERY PIPES AND INJECTORS(a) Install the grommet and a new O±ring to each injector.
(b) W h i l e t u r n i n g t h e I n j e c t o r c l o c k w i s e a n dcounterclockwise, push it to delivery pipe. Install the
eight injectors.
(c) Position the injector connector outward.
(d) Place the eight insulators and four spacers in positions on the intake manifold.
(e) P l a c e t h e e i g h t i n j e c t o r s a n d t w o d e l i v e r y p i p e s assembly in position on the intake manifold.
(f) Temporarily install the c onnector bracket and four
mounting nuts.
(g) Check that the injectors rotates smoothly.
(h) Position the injector connectors outward.
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