engine LEXUS SC400 1991 Service Repair Manual

HINT: If using a standard bearing, replace with one having
the same number. If the number of the bearing cannot be de-
termined, select the correct bearing by adding together the
numbers imprinted on the connecting rod cap and crank-
shaft, then select the bearing with the same number as the
total. There are five sizes of standard bearings, marked º1º,
º2º, º3º, º4º and º5º accordingly.
 Number mark
 Connecting rod cap123
Crankshaft012012012 Use bearing 1 2 3 2 3 4 3 4 5
EXAMPLE: Connecting rod cap º3º + Crankshaft º1º = Total
number 4 (Use bearing º4º)
(Reference)
Connecting rod big end inside diameter:Mark º1º 55.025±55.031 mm
(2.1663±2.1666 in.)
Mark º2º 55.031±55.037 mm
(2.1666±2.1668 in.)
Mark º3º 55.037±55.043 mm
(2.1668±2.1670 in.)
U/S 0.25 55.025±55.043 mm
(2.1663±2.1670 in.)
Crankshaft crank pin diameter: Mark º0º 51.994±52.000 mm (2.0470±2.0472 in.)
Mark º1º 51.988±51.994 mm (2.0468±2.0470 in.)
Mark º2º 51.982±51.988 mm (2.0465±2.0468 in.)
U/S 0.25 51.745±51.755 in.) (2.0364±2.0376 in.)
Bearing center wall thickness: Mark º1º 1.492±1.495 mm (0.0587±0.0589 in.)
Mark º2º 1.495±1.498 mm
(0.0589±0.0590 in.)
Mark º3º 1.498±1.501 mm (0.0590±1.501 in.)
Mark º4º 1.501±1.504 mm (0.0591±0.0592 in.)
Mark º5º 1.504±1.507 mm (0.0592±0.0593 in.)
U/S 0.25 1.610±1.615 mm (0.0634±0.0636 in.)
(j) Completely remove the Plastigage.
4. REMOVE PISTON AND CONNECTING ROD ASSEMBLIES
(a) Using a ridge reamer, remove all the carbon from the top
of the cylinder.
(b) Push the piston, connecting rod assembly and upper bearing through the top of the cylinder block.
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ENGINE MECHANICAL Cylinder BlockEM±79
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HINT:
wKeep the bearings, connecting rod and cap together.
w Arrange the piston and connecting rod assemblies in
correct order.
5. CHECK CRANKSHAFT THRUST CLEARANCE Using a dial indi cator, measure the thrust clearance while pry-
ing the crankshaft back and forth with a screwdriver.
Standard thrust clearance: 0.020±0.220 mm
(0.0008±0.0087 in.)
Maximum thrust clearance: 0.30 mm (0.0118 in.)
If the thrust clearance is greater than maximum, replace the
thrust washers as a set.
Thrust washer thickness:
1.940±1.990 mm (0.0764±0.0783 in.)
6. REMOVE MAIN BEARING CAPS AND CHECK OILCLEARANCE
(a) Remove the main bearing cap bolts.
(b) Using the removed main bearing cap bolts, pry the main
bearing cap back and forth, and remove the main
bearing caps, lower bearings and lower thrust washers
(No. 4 main bearing cap only).
HINT:
w Keep the lower bearing and main bearing cap together.
w Arrange the main bearing caps and lower thrust
washers in correct order.
(c) Lift out the crankshaft.
HINT: Keep the upper bearing and upper thrust washer to-
gether with the cylinder block.
EM±80
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(d) Clean each main journal and bearing.
(e) Check each main journal and bearing for pitting andscratches.
If the journal or bearing is damaged, replace the bearings.
If necessary, grind or replace the crankshaft.
(f) Place the crankshaft on the cylinder block.
(g) Lay a strip of Plastigage across each journal.
(h) Install the main bearing caps.
(See step 4 on pages EM±97 and 98)
Torque: 1st 44 N Vm (450 kgf Vcm, 33 ft Vlbf)
2nd turn 90 5
HINT: Do not turn the crankshaft.
(i) Remove the main bearing caps.
(See procedures (a) and (b) above)
(j) Measure the Plastigage at its widest point.
Standard clearance:
STD size 0.026±0.040 mm (0.0010±0.0016 in.)
U/S 0.25 0.025±0.061 mm (0.0010±0.0024 in.)
Maximum clearance: STD size 0.06 mm (0.0024 in.)
U/S 0.25 0.08 mm (0.0031 in.)
If the oil clearance is greater than maximum, replace the bearings.
If necessary, replace the crankshaft.
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HINT: If using a standard bearing, replace with one having
the same number. If the number of the bearing cannot be de-
termined, select the correct bearing by adding together the
numbers imprinted on the cylinder block and crankshaft, then
refer to the table below for the appropriate bearing number.
There are five sizes of standard bearings, marked º1º, º2º, º3º\
,
º4º and º5º accordingly.
  Total number ºº: Number mark
Cylinder block (A) +0±23±56±89±1112±14 Crankshaft (B) = Use bearing º1º º2º º3º º4º º5º
EXAMPLE: Cylinder block º3º (A)
+ Crankshaft º4º (B)
= Total number 7 (Use bearing º3º)
(Reference)
Cylinder block main journal bore diameter (A):Mark º0º 66.020±66.022 mm (2.59921±2.59929 in.)
Mark º1º 66.022±66.024 mm (2.59929±2.59937 in.)
Mark º2º 66.024±66.026 mm
(2.59937±2.59945 in.)
Mark º3º 66.026±66.028 mm
(2.59945±2.59953 in.)
Mark º4º 66.028±66.030 mm
(2.59953±2.59961 in.)
Mark º5º 66.030±66.032 mm
(2.59961±2.59969 in.)
Mark º6º 66.032±66.034 mm
(2.59969±2.59976 in.)
Mark º7º 66.034±66.036 mm
(2.59976±2.59984 in.)
U/S 0.25 66.020±66.036 mm
(2.59921±2.59984 in.)
Crankshaft main journal diameter (B):
Mark º0º 61.998±62.000 mm(2.44087±2.44095 in.)
Mark º1º 61.996±61.998 mm (2.44079±2.44087 in.)
Mark º2º 61.994±61.996 mm (2.44071±2.44079 in.)
Mark º3º 61.992±61.994 mm (2.44063±2.44071 in.)
Mark º4º 61.990±61.992 mm (2.44055±2.44063 in.)
Mark º5º 61.988±61.990 mm
(2.44047±2.44055 in.)
Mark º6º 61.986±61.988 mm
(2.44039±2.44047 in.)
Mark º7º 61.984±61.986 mm
(2.44031±2.44039 in.)
U/S 0.25 61.745±61.755 mm
(2.43091±2.43130 in.)
EM±82±
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Bearing center wall thickness:
Mark º1º 1.994±1.997 mm(0.0785±0.0786 in.)
Mark º2º 1.997±2.000 mm (0.0786±0.0787 in.)
Mark º3º 2.000±2.003 mm (0.0787±0.0789 in.)
Mark º4º 2.003±2.006 mm
(0.0789±0.0790 in.)
Mark º5º 2.006±2.009 mm (0.0790±0.0791 in.)
U/S 0.25 2.114±2.120 mm
(0.0832±0.0835 in.)
Standard sized Bearing Selection Chart
 Crankshaft number mark Cylinder block number mark
 
Crankshaft number mark01234567
011122233 1 1 1 2 2 2 3 3 3 2 1 2 2 2 3 3 3 4 3 2 2 2 3 3 3 4 4 4 2 2 3 3 3 4 4 4
 5 2 3 3 3 4 4 5 5
 6 3 3 3 4 4 5 5 5
 7 3 3 4 4 5 5 5 5
EXAMPLE: Cylinder block º3º, Crankshaft º4º= Use bearing º3º
(k) Completely remove the Plastigage.
7. REMOVE CRANKSHAFT (a) Lift out the crankshaft
(b) Remove the upper bearings and upper thrust washersfrom the cylinder block.
HINT: Arrange the main bearing caps, bearings and thrust
washers in correct order.
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INSPECTION AND REPAIR OF
CYLINDER BLOCK
1. CLEAN CYLINDER BLOCK
A. Remove gasket materialUsing a gasket scraper, remove all the gasket material from
the cylinder block surface.
B. Clean cylinder block Using a soft brush and solvent, thoroughly clean the cylinder
block.
2. INSPECT CYLINDER BLOCK SURFACE FOR FLATNESS Using precision straight edge and feeler gauge, measure the
top surfaces of the cylinder block 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.
4. INSPECT CYLINDER BORE DIAMETER (a) Using a cylinder gauge, measure the cylinder borediameter at positions A, B and C in the thrust and axial
directions.
Standard diameter: 86.000±86.013 mm
(3.3858±3.3863 in.)
Maximum diameter: 86.02 mm (3.3866 in.)
If the diameter is greater than maximum, replace the cylinder
block.
(b) Difference between measurements A, B and C is greater than taper limit.
Taper limit: 0.01 mm (0.0004 in.)
(c) Difference between the thrust and axial measurementsis greater than out±of±round limit.
Out±of±round limit: 0.02 mm (0.0008 in.)
EM±84±
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5. REMOVE CYLINDER RIDGEIf 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 BOLTS Using vernier calipers, measure the minimum diameter of the
compressed thread at the measuring point.
Standard diameter: 9.96±9.97 mm
(0.3921±0.3925 in.)
Minimum diameter: 9.7 mm (0.3819 in.)
If the diameter is less than minimum, replace the bolt.
DISASSEMBLY OF PISTON AND
CONNECTING ROD ASSEMBLIES
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 two compression rings.
(b) Remove the two side rails and oil ring expander by hand. HINT: Arrange the piston rings in correct order only.
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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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