ect LEXUS SC300 1991 Service Repair Manual

HINT:
wThe piston and pin are a matched set.
w Arrange the pistons, pins, rings, connecting rods and
bearings in correct order.
PISTON AND CONNECTING ROD
INSPECTION
EG1KY±02
1. CLEAN PISTON
(a) Using a gasket scraper, remove the carbon from the piston
top.
(b) Using a groove cleaning tool or broken ring, clean the piston ring grooves.
(c) Using solvent and a brush, thoroughly clean the piston.
NOTICE: Do not use a wire brush.
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2. INSPECT PISTON
A. Inspect piston oil clearanceHINT: There are 3 sizes of the standard piston diameter,
marked ª1º, ª2º and ª3º accordingly. The mark is stamped on
the piston top.
(a) Using a micrometer, measure the piston diameter at ring angles to the piston pin center line, 49 mm (1.93 in.) f rom the
piston head.
Piston diameter:
Mark ª1º87.470 ± 87.480 mm (3.4437 ± 3.4441 in.)
Mark ª2º 87.480 ± 86.490 mm (3.4441 ± 3.4445 in.)
Mark ª3º 87.490 ± 87.500 mm (3.4445 ± 3.4449 in.)
(b) Measure the cylinder bore diameter in the thrust directions. (See step 4 on page EG±xxx)
(c) Subtract the piston diameter measurement from the cylinder bore diameter measurement.
Standard oil clearance:
0.020 ± 0.040 mm (0.0008 ± 0.0016 in.)
Maximum oil clearance: 0.06 mm (0.0024 in.)
If the oil clearance is greater than maximum, replace all the
8 pistons. If necessary, replace the cylinder block.
HINT (Use new cylinder block):
wUse a piston with the same number mark as the cylinder
diameter marked on the cylinder block.
w The shape of the piston varies for the RH and LH banks.
The RH piston is marked with ªRº, the LH piston with ªLº.
EG±170±
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B. Inspect piston ring groove clearanceUsing a feeler gauge, measure the clearance between new
piston ring and the wall of the ring groove
Ring groove clearance:
No.10.020 ± 0.060 mm (0.0008 ± 0.0024 in.)
No.2
0.015 ± 0.055 mm (0.0006 ± 0.0022 in.)
If the clearance is not as specified, replace the piston.
C. Inspect piston ring and gap
(a) Insert the piston ring into the cylinder bore.
(b) Using a piston, push the piston ring a little beyond the bottom
of the ring travel, 105 mm (4.13 in.) from the top of the cylinder
block.
(c) Using a feeler gauge, measure the end gap.
Standard end gap: No.10.250 ± 0.450 mm (0.0098 ± 0.0177 in.)
No.2 0.350 ± 0.600 mm (0.0138 ± 0.0236 in.)
Oil (Side rail)
0.160 ± 0.500 mm (0.0059 ± 0.0197 in.)
Maximum end gap: No.11.05 mm (0.0413 in.)
No.2 1.20 mm (0.0472 in.)
Oil (Side rail) 1.10 mm (0.0433 in.)
If the end gap is greater than maximum, replace the piston
ring. If the end gap is greater than maximum, even with a new
piston ring, replace the cylinder block.
D. Inspect piston pin fit At 60 5C (140 5F), you should be able to push the piston pin
into the piston pin hole with your thumb.
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3. INSPECT CONNECTING ROD
A. Inspect connecting rod alignmentUsing a rod aligner and feeler gauge, check the connecting
rod alignment.
wCheck for bend.
Maximum bend:
0.05 mm (0.0020 in.) per 100 mm (3.94 in.)
If bend is greater than maximum, replace the connecting rod
assembly.
wCheck for twist
Maximum twist:
0.15 mm (0.0059 in.) per 100 mm (3.94 in.)
If twist is greater than maximum, replace the connecting rod
assembly.
B. Inspect piston pin oil clearance
(a) Using a caliper gauge, measure the inside diameter of the connecting rod bushing.
Bushing inside diameter:
22.005 ± 22.017 mm (0.8663 ± 0.8668 in.)
(b) Using a micrometer, measure the piston pin diameter.
Piston pin diameter:21.997 ± 22.009 mm (0.8660 ± 0.8665 in.)
(c) Subtract the piston pin diameter measurement from thebushing inside diameter measurement.
Standard oil clearance:
0.005 ± 0.011 mm (0.0002 ± 0.0004 in.)
Maximum oil clearance: 0.05 mm (0.0020 in.)
If the oil clearance is greater than maximum, replace the
bushing. If necessary, replace the piston and piston pin as a
set.
EG±172
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C. If necessary, replace connecting rod bushing
(a) Using SST and a press, press out the bushing.SST 09222±30010
(b) Align the oil holes of a new bushing and the connecting rod.
(c) Using SST and a press, press out the bushing SST 09222±30010
(d) Using a pin hole grinder, hone the bushing to obtain the standard specified clearance (see step B above) between
the bushing and piston pin.
(e) Check the piston pin fit at normal room temperature. Coat the piston pin with engine oil, and push it into the con-
necting rod with your thumb.
D. Inspect connecting rod bolts Using a vernier caliper, measure the tension portion of of the
connecting rod bolt.
Standard diameter:
7.200 ± 7.300 mm (0.2835 ± 0.2874 in.)
Maximum diameter: 7.00 mm (0.2756 in.)
HINT: If the tension portion diameter is less than minimum,
replace the connecting rod bolt.
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CRANKSHAFT INSPECTION
EG0BY±0D
1. INSPECT CRANKSHAFT FOR CIRCLE RUNOUT
(a) Place the crankshaft 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
crankshaft.
2. INSPECT MAIN JOURNALS AND CRANK PINS
(a) Using a micrometer, measure the diameter of each main journal and crank pin.
Main journal diameter:
66.988 ± 67.000 mm (2.6373 ± 2.6378 in.)
Crank pin diameter: 51.982 ± 52.000 mm (2.0465 ± 2.0472 in.)
If the diameter is not as specified, check the oil clearance
(See steps 3 or 6 on page EG±156 or 160). If necessary, re-
place the crankshaft.
(b) Ch e ck ea ch ma in jo u rn a l an d cra n k pin fo r t aper and
out±of±round as shown.
Maximum taper and out±of±round:
0.02 mm (0.0008 in.)
If the taper and out±of±round is greater than maximum, re-
place the crankshaft.
EG±174
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PISTON AND CONNECTING ROD
ASSEMBLY
EG0C1±07
1. ASSEMBLE PISTON AND CONNECTING ROD
(a) Using a small screwdriver, install a new snap ring on one side
of the piston pin hole.
(b) Gradually heat the piston to about 60
C (140
F).
(c) Coat the piston pin with engine oil.
(d) Position the piston front mark with respect to the outside mark
on the connecting rod as shown in the diagram.
NOTICE: The installation direction of the piston and con-
necting rod are different for the RH and LH banks. The RH
piston is marked with ªRº, the LH piston with ªLº.
(e) Align the piston pin holes of the piston and connecting rod,
and push in the piston pin with your thumb.
(f) Using a small screwdriver, install a new snap ring on the other
side of the piston pin hole.
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2. INSTALL PISTON RINGS
(a) Install the oil ring expander and 2 side rails by hand.
(b) Using a piston ring expander, install the 2 compression ringswith the code mark facing upward.
Code mark:
No.11R or T
No.2 2R or 2T
(c) Position the piston rings so that the ring ends are as shown. NOTICE: Do not align the ring ends.
3. INSTALL BEARINGS
(a) Align the bearing claw with the groove of the connecting rod or connecting cap.
(b) Install the bearings in the connecting rod and connecting rod cap.
EG±178
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6. INSTALL PISTON AND CONNECTING ROD ASSEMBLESUsing a piston ring compressor, push the correctly numbered
piston and connecting rod assemblies into each cylinder with
the front mark of the piston facing forward.
NOTICE: The shape of the piston varies for the RH and LH
banks. The RH piston is marked with ªRº, the LH piston
with ªLº.
7. INSTALL CONNECTING ROD CAPS
A. Place connecting rod cap on connecting rod
(a) Match the numbered connecting rod cap with the connecting rod.
(b) Align the pin groove of the connecting rod cap with the pins of the connecting rod, and install the connecting rod.
(c) Check that the outside mark of the connecting rod cap is facing in correct direction.
EG±182
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B. Install connecting rod cap boltsHINT:
wThe connecting rod cap bolts are tightened in 2
progressive steps (steps (b) and (d)).
w If any one of the connecting rod cap bolts is broken or
deformed, replace it.
(a) Apply a light coat of engine oil on the threads and under the heads of the connecting rod cap bolts.
(b) Install and alternately tighten the 2 connecting rod cap bolts
in several passes.
Torque: 25 N Vm (250 kgf Vcm, 18 ft Vlbf)
If any one of the connecting rod cap bolts does not meet the
torque specification, replace the connecting rod cap bolts.
(c) Mark the front of the connecting cap bolt with paint.
(d) Retighten the cap nuts 90
as shown.
(e) Check that the painted mark is now at a 90
angle to the front.
(f) Check that the crankshaft turns smoothly.
8. CHECK CONNECTING ROD OIL CLEARANCE
Using a dial indicator, measure the thrust clearance while
moving the connecting rod back and forth.
Standard thrust clearance:
0.160 ± 0.290 mm (0.0063 ± 0.0138 in.)
Maximum thrust clearance: 0.35 mm (0.0138 in.)
If the thrust clearance is greater than maximum, replace the
connecting rod assembly(s). If necessary, replace the crank-
shaft.
Connecting rod thickness:22.880 ± 22.920 mm (0.9008 ± 0.9024 in.)
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