LEXUS SC400 1991 Service Repair Manual

CYLINDER BLOCK INSPECTION AND
REPAIR
EG1KU±01
1. CLEAN CYLINDER BLOCK
A. Remove gasket materialUsing a gasket scraper, remove all the gasket material from
the top surface of the cylinder block.
B. Clean cylinder block
Using a soft brush and solvent, thoroughly clean the cylinder
block.
NOTICE: If the cylinder is washed at high temperatures, the
cylinder liner sticks out beyond the cylinder block, so always
wash the cylinder block at temperature of 45
or less.
2. INSPECT TOP SURFACE OF CYLINDER BLOCK FOR
FLATNESS
Using a precision straight edge and feeler gauge, measure
the surface contacting the cylinder head gasket for warpage.
Maximum warpage:
0.07 mm (0.0028 in.)
If warpage is greater than maximum, replace the cylinder
block.
3. INSPECT CYLINDER FOR VERTICAL SCRATCHES Visually check the cylinder for vertical scratches.
If deep scratches are present, replace the cylinder block.
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4. INSPECT CYLINDER BORE DIAMETERHINT: There are 3 sizes of the standard cylinder bore diame-
ter, marked ª1º, ª2º and ª3º accordingly. The mark is stamped
on the top of the cylinder block.
Using a cylinder gauge, measure the cylinder bore diameter
at positions A, B and C in the thrust and axial directions.
Standard diameter:
Mark ª1º87.500 ± 87.510 mm (3.4449 ± 3.4453 in.)
Mark ª2º 87.510 ± 87.520 mm (3.4453 ± 3.4457 in.)
Mark ª3º 87.520 ± 87.530 mm (3.4457 ± 3.4461 in.)
Maximum diameter: 87.73 mm (3.4539 in.)
If the diameter is greater than maximum, replace the cylinder
block.
5. REMOVE CYLINDER RIDGE If the wear is less than 0.2 mm (0.008 in.), using a ridge ream-
er, grind the top of the cylinder.
6. INSPECT MAIN BEARING CAP STUD BOLTS Using a vernier caliper, measure the tension portion diameter
of the stud bolt.
Standard diameter:
7.500 ± 7.600 mm (0.2953 ± 0.2992 in.)
Minimum diameter: 7.40 mm (0.2913 in.)
If the diameter is less than minimum, replace the stud bolt.
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7. IF NECESSARY, REPLACE MAIN BEARING CAP STUDBOLTS
(a) Using the 2 main bearing cap nuts, remove the stud bolt.
(b) Apply a light coat of engine oil on the threads and under
flange of new stud bolts.
(c) Using the 2 main bearing cap nuts, install the stud bolt.
Torque: 15 N Vm (150 kgf Vcm, 11 ft Vlbf)
HINT: Stud bolts come in lengths of 90.0 mm (3.543 in.) and
101.5 mm (3.996 in.). Install the 101.5 mm (3.996 in.) bolts
in inside positions. Install the 90.0 mm (3.543 in.) bolts in out-
side positions.
PISTON AND CONNECTING ROD
DISASSEMBLY
EG0BV±06
1. CHECK FIT BETWEEN PISTON AND PISTON PIN
Try to move the piston back and forth on the piston pin.
If any movement is felt, replace the piston and pin as a set.
2. REMOVE PISTON RINGS
(a) Using a piston ring expander, remove the 2 compression rings.
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(b) Remove the 2 side rails and oil ring by hand.HINT: Arrange the piston rings in correct order only.
3. DISCONNECT CONNECTING ROD FROM PISTON
(a) Using a small screwdriver, pry out the 2 snap rings.
(b) Gradually heat the piston to approx. 60
C (140
F).
(c) Using a plastic±faced hammer and brass bar, lightly tap out the piston pin and pin and remove the connecting rod.
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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.
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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.
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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.
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