LEXUS SC400 1991 Service Repair Manual

3. DISCONNECT CONNECTING ROD FROM PISTON(a) Using a small screwdriver, remove the snap rings.
(b) Gradually heat the piston to about 80
C (176
F).
(c) Using a plastic±faced hammer and brass bar, lightly tap out the piston pin and remove the connecting rod.
HINT:
w The piston and pin are a matched set.
w Arrange the pistons, pins, rings, connecting rods and
bearings in correct order.
EM±86
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INSPECTION OF PISTON AND
CONNECTING ROD ASSEMBLIES
1. CLEAN PISTON(a) Using a gasket scraper, remove the carbon from thepiston 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.
2. INSPECT PISTON
A. Inspect piston oil clearance (a) Using a micrometer, measure the piston diameter at
right angles to the piston pin center line, 34 mm (1.34 in.)
from the piston head.
Piston diameter: 85.935±85.945 mm
(3.3833±3.3837 in.)
(b) Me a su re th e cylinder bore diameter in the thrust
directions. (See step 4 on page EM±84)
(c) Subtract the piston diameter measurement from the cylinder bore diameter measurement.
Standard oil clearance: 0.055±0.078 mm
(0.0022±0.0031 in.)
Maximum oil clearance: 0.10 mm (0.0039 in.)
If the oil clearance is greater than maximum, replace all the
six pistons. If necessary, replace the cylinder block.
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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 piston ring groove.
Ring groove clearance:
No. 1 0.011±0.07 mm (0.0004±0.0028 in.)
No. 2 0.03±0.07 mm (0.0012±0.0028 in.)
If the clearance is not as specified, replace the piston.
C. Inspect piston ring end gap (a) Insert the piston ring into the cylinder bore.
(b) Using a piston, push the piston ring a little beyond thebottom of the ring travel, 130 mm (5.12 in.) from the top
of the cylinder block.
(c) Using a feeler gauge, measure the ring end gap.
Standard ring end gap: No. 1 0.30±0.47 mm (0.0120±0.0188 in.)
No. 2 0.35±0.52 mm (0.0138±0.0208 in.)
Oil (Side rail) 0.13±0.45 mm
(0.0051±0.0177 in.)
Maximum ring end gap: No. 1 1.07 mm (0.0428 in.)
No. 2 1.12 mm (0.0448 in.)
Oil (Side rail) 1.05 mm (0.0420 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 80 5C (176 5F), you should be able to push the piston pin
into the piston pin hole with your thumb.
If the piston pin can be pushed in at room temperature, the
piston and the piston pin must be replaced as a set.
EM±88
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3. INSPECT CONNECTING ROD
A. Inspect connecting rod alignmentUsing a feeler gauge and rod aligner, check the connecting
rod alignment.w Check 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.
w Check 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 ofthe connecting rod bushing.
Bushing inside diameter: 22.005±22.014 mm
(0.8663±0.8667 in.)
(b) Using a micrometer, measure the piston pin diameter.
Piston pin diameter: 21.997±22.006 mm(0.8660±0.8664 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 connectingrod.
(c) Using SST and a press, press in the bushing.
SST 09222±30010
(d) Using a pin hole grinder, bore 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 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 vernier calipers, measure the minimum diameter of the
compressed bolt at the measuring point.
Standard diameter: 8.2±8.3 mm
(0.325±0.327 in.)
Minimum diameter: 8.0 mm (0.315 in.)
If the diameter is less than minimum, replace the connecting
rod bolt.
EM±90
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INSPECTION OF CRANKSHAFT
1. INSPECT CRANKSHAFT FOR RUNOUT(a) Place the crankshaft on V±blocks.
(b) Using a dial indicator, measure the circle runout at thecenter journal.
Maximum circle runout: 0.06 mm (0.0024 in.)
If the circle runout is greater than maximum, replace the
crankshaft.
2. INSPECT MAIN JOURNALS AND CRANK PINS (a) Using a micr ometer, measure the diameter of each main
journal and crank pin.
Main journal diameter: 61.984±62.000 mm
(2.4403±2.4409 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 page EM±77 or EM±80).
(b) Check each main journal and crank pin for taper andout±of±round as shown.
Maximum taper and out±of round: 0.02 mm
(0.0008 in.)
If the taper or out±of±round is greater than maximum, re-
place the crankshaft.
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REPLACEMENT OF CRANKSHAFT OIL
SEALS
1. REPLACE CRANKSHAFT FRONT OIL SEALHINT: There are two methods, A and B, to replace the oil seal
as follows:
A. If oil pump is removed from cylinder block: (a) Using a screwdriver, pry out the oil seal.
(b) Using SST and a hammer, tap in a new oil seal until itssurface is flush with the oil pump body edge.
SST 09316±60010 (09316±00010)
(c) Apply MP grease to the oil seal lip.
B. If oil pump is installed on cylinder block: (a) Using a knife, cut off the oil seal lip.
(b) Using a screwdriver, pry out the oil seal.
NOTICE: Be careful not to damage the crankshaft. Tape
the screwdriver tip.
(c) Apply MP grease to a new oil seal lip.
(d) Using SST and a hammer, tap in the oil seal until itssurface is flush with the oil pump body edge.
SST 09316 60010 (09316±00010)
EM±92
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2. REPLACE CRANKSHAFT REAR OIL SEALHINT: There are two methods, A and B, to replace the oil seal
as follows:
A. If rear oil seal retainer is removed from cylinder block: (a) Using a screwdriver and hammer, tap out the oil seal.
(b) Using SST and a hammer, tap in a new oil seal until itssurface is flush with the rear oil seal retainer edge.
SST 09223±15030, 09608±30022 (09608±05010)
(c) Apply MP grease to the oil seal lip.
B. If rear oil seal retainer is installed on cylinder block: (a) Using a knife, cut off the oil seal lip.
(b) Using a screwdriver, pry out the oil seal.
NOTICE: Be careful not to damage the crankshaft.
Tape the screwdriver tip.
(c) Apply MP grease to a new oil seal lip.
(d) Using SST and a hammer, tap in the oil seal until itssurface is flush with the rear oil seal retainer edge.
SST 09223±15030, 09608±30022 (09608±05011)
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ASSEMBLY OF PISTON AND
CONNECTING ROD ASSEMBLIES
1. ASSEMBLE PISTON AND CONNECTING ROD(a) Install a new snap ring at one end of the piston pin hole.
HINT: Be sure that end gap of the snap ring is not aligned with
the pin hole cutout portion of the piston.
(b) Gradually heat the piston to about 80
C (176
F).
(c) Coat the piston pin with engine oil..
(d) Align the front marks of the piston and connecting rod, and push in the piston pin with your thumb.
(e) Install a new snap ring at the other end of the piston pin hole.
HINT: Be sure that end gap of the snap ring is not aligned with
the pin hole cutout portion of the piston.
2. INSTALL PISTON RINGS (a) Install the oil ring expander and two side rails by hand.
EM±94
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(b) Using a piston ring expander, install the twocompression rings with the code mark facing up.
Code mark: No.1 1T
No.2 2T
(c) Position the piston rings so that the ring ends are asshown.
NOTICE: Do not align the piston ring ends.
3. INSTALL BEARINGS (a) Align the bearing claw with the groove of the connectingrod and connecting cap.
(b) I n s t a l l t h e b e a r i n g s i n t h e c onnecting rod and
connecting rod cap.
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