engine LEXUS SC400 1991 Service Repair Manual

(c) Using two screwdrivers, pry out the main bearing cap,and remove the five main bearing cap, lower main
bearings and two lower thrust washers (No.3 main
bearing cap only).
NOTICE: Be careful not to damage the cylinder block.
HINT:
w Keep the lower main bearing and main bearing cap
together.
w Arrange the main bearing caps and lower thrust
washers in correct order.
(d) Lift out the crankshaft.
(e) Remove the two upper thrust washers.
HINT:
w Arrange the upper thrust washers in correct order.
w Keep the upper main bearings together with the cylinder
block.
(f) Clean each main journal and bearing.
(g) Check each main journal and bearing for pitting and scratches.
If the journal or bearing are damaged, replace the bearings.
If necessary, replace the crankshaft.
(h) Install the five main bearing caps with the twenty nuts and ten bolts. Do not install the crankshaft.
(See step 4 on pages EM±157 and 158)
Torque:
Nut 1st 27 N Vm (275 kgf Vcm, 20 ft Vlbf)
2nd Turn 90 5
Bolt 49 N Vm (500 kgf Vcm, 36 ft Vlbf)
(i) Using a cylinder gauge, measure the inside diameter of
the main bearing.
Bearing inside diameter: 67.026±67.033 mm
(2.6388±2.6391 in.)
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ENGINE MECHANICAL Cylinder BlockEM±139
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(j) Using a micrometer, measure the diameter of the mainjournal.
Main journal diameter: 66.988±67.000 mm
(2.6373±2.6378 in.)
(k) Subtract the main journal diameter measurement fromthe main bearing inside diameter measurement.
Standard oil clearance: 0.026±0.045 mm
(0.0010±0.0018 in.)
Maximum clearance: 0.055 mm (0.0022 in.)
If the oil clearance is greater than maximum, replace the
bearings. If necessary, replace the crankshaft.
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 º º: Number mark
 Cylinder block (A)     
+0±56±1112±1718±2324±28 Crankshaft (B) =     
 Use bearing º1º º2º º3º º4º º5º
EXAMPLE: Cylinder block º06º (A)
+ Crankshaft º08º (B)
= Total number 14 (Use bearing º3º)
(Reference)
Cylinder block main journal bore diameter (A):
Mark º00º 72.000 mm (2.8346 in.)
Mark º01º 72.001 mm (2.8347 in.)
Mark º02º 72.002 mm (2.8347 in.)
Mark º03º 72.003 mm (2.8348 in.)
Mark º04º 72.004 mm (2.8348 in.)
Mark º05º 72.005 mm (2.8348 in.)
Mark º06º 72.006 mm (2.8349 in.)
Mark º07º 72.007 mm (2.8349 in.)
Mark º08º 72.008 mm (2.8350 in.)
Mark º09º 72.009 mm (2.8350 in.)
Mark º10º 72.010 mm (2.8350 in.)
Mark º11º 72.011 mm (2.8351 in.)
Mark º12º 72.012 mm (2.8351 in.)
Mark º13º 72.013 mm (2.8352 in.)
Mark º14º 72.014 mm (2.8352 in.)
Mark º15º 72.015 mm (2.8352 in.)
Mark º16º 72.016 mm (2.8353 in.)
EM±140±
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Crankshaft main journal diameter (B):Mark º00º 67.000 mm (2.6378 in.)
Mark º01º 66.999 mm (2.6378 in.)
Mark º02º 66.998 mm (2.6377 in.)
Mark º03º 66.997 mm (2.6377 in.)
Mark º04º 66.996 mm (2.6376 in.)
Mark º05º 66.995 mm (2.6376 in.)
Mark º06º 66.994 mm (2.6376 in.)
Mark º07º 66.993 mm (2.6375 in.)
Mark º08º 66.992 mm (2.6375 in.)
Mark º09º 66.991 mm (2.6374 in.)
Mark º10º 66.990 mm (2.6374 in.)
Mark º11º 66.989 mm (2.6374 in.)
Mark º12º 66.988 mm (2.6373 in.)
Standard sized bearing center wall thickness: Mark º1º 2.486±2.489 mm
(0.0979±0.0980 in.)
Mark º2º 2.489±2.492 mm (0.0980±0.0981 in.)
Mark º3º 2.492±2.495 mm (0.0981±0.0982 in.)
Mark º4º 2.495±2.498 mm (0.0982±0.0983 in.)
Mark º5º 2.498±2.501 mm (0.0983±0.0985 in.)
Standard sized Bearing Selection Chart
 

Crankshaft
number mark
\
 
\

\
Cylinder block number mark
 
number mark
 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16
 00 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3
 01 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3
 02 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 4
 03 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 4 4
 04 1 1 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4
 05 1 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4
 06 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4
 07 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4
 08 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5
 09 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 10 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 11 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 12 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 5
EXAMPLE: Cylinder block º06º, Crankshaft º08º = Use
bearing º3º
±
ENGINE MECHANICAL Cylinder BlockEM±141
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(k) Remove the ten bolts, twenty nuts and five main bearingcaps. (See procedure (a) to (c) above)
(l) Remove the five upper main bearings from the cylinder block.
HINT: Arrange the main bearing caps, bearings and thrust
washers in correct order.
INSPECTION AND REPAIR OF
CYLINDER BLOCK
1. CLEAN CYLINDER BLOCK
A. Remove gasket material Using a gasket scraper, remove all the gasket material from
the top surfaces 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 5 or
less.
2. INSPECT TOP SURFACES OF CYLINDER BLOCK 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.
EM±142
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3. INSPECT CYLINDER FOR VERTICAL SCRATCHESVisually check the cylinder for vertical scratches.
If deep scratches are present, replace the cylinder block.
4. INSPECT CYLINDER BORE DIAMETER HINT: There are three sizes of the standard cylinder bore di-
ameter, marked º1º, º2º and º3º accordingly. The marked 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 º1º 87.500±87.510 mm (3.4449±3.4453 in.)
Mark º2º 87.510±87.520 mm (3.4453±3.4457 in.)
Mark º3º 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.
±
ENGINE MECHANICAL Cylinder BlockEM±143
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6. INSPECT MAIN BEARING CAP STUD BOLTSUsing 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.
7. IF NECESSARY, REPLACE MAIN BEARING CAP STUD BOLTS
(a) Using the two main bearing cap nuts, remove the studbolt.
(b) Apply a light coat of engine oil on the threads and under
the flange of the stud bolt.
(c) Using the two main bearing cap nuts, install and torque
the stud bolt.
Torque: 10 N Vm (100 kgf Vcm, 7 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.
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.
EM±144
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2. REMOVE PISTON RINGS(a) U s i n g a p i s t o n r i n g e x pander, 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.
3. DISCONNECT CONNECTING ROD FROM PISTON (a) Using a small screwdriver, pry out the two snap rings.
(b) Gradually heat the piston to approx. 60 °C (140 °F).
(c) Using a plastic±face hammer and brass bar, lightly tap out the piston pin and remove the connecting rod.
±
ENGINE MECHANICAL Cylinder BlockEM±145
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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.
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.
EM±146
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2. INSPECT PISTON
A. Inspect piston oil clearanceHINT: There are three sizes of the standard piston, marked
º1º, º2º and º3º accordingly. The mark is stamped on the top
of the piston.
(a) Using a micrometer, measure the piston diameter atright angles to the piston pin center line, 49 mm (1.93 in.)
from the piston head.
Piston diameter:
Mark º1º 87.470±87.480 mm (3.4437±3.4441 in.)
Mark º2º 87.480±87.490 mm
(3.4441±3.4445 in.)
Mark º3º 87.490±87.500 mm (3.4445±3.4449 in.)
(b) Me a su re th e cyli nder bore diameter in the thrust
directions. (See step 4 on page EM±143)
(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
eight pistons. If necessary, replace the cylinder block.
HINT (Use new cylinder block):
w Use a piston with the same size mark as the cylinder
bore diameter size mark on the cylinder block.
w The shape of the piston varies for the RH and LH banks.
The RH piston is marked with ºRº, the LH piston with ºLº.
±
ENGINE MECHANICAL Cylinder BlockEM±147
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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 0.020±0.060 mm (0.0008±0.0024 in.)
No.2 0.015±0.055 mm (0.0006±0.0022 in.)
If the clearance is greater than maximum, 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, 105 mm (4.13 in.) from the top
of the cylinder block.
(c) Using a feeler gauge, measure the ring end gap.
Standard ring end gap: No.1 0.250±0.450 mm(0.0098±0.0177 in.)
No.2 0.350±0.600 mm (0.0138±0.0236 in.)
Oil (Side rail) 0.150±0.500 mm
(0.0059±0.0197 in.)
Maximum ring end gap: No.1 1.05 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.
EM±148
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