light LEXUS SC400 1991 Service Repair Manual

(a) Apply a light coat of engine oil on the threads and under themain bearing cap nuts.
(b) Install and uniformly tighten the 20 main bearing cap nuts in
several passes, in the sequence shown.
Torque: 27 N Vm (275 kgf Vcm, 20 ft Vlbf)
If any one of the main bearing cap nuts does not meet the
torque specification, replace the main bearing cap stud bolt.
(c) Mark the front of the main bearing cap nut with paint.
(d) Retighten the main bearing cap bolts 90
in the numerical
order shown.
(e) Check that the painted mark is now at a 90
angle to the front.
C. Install main bearing cap bolts
(a) Install a new seal washer to the main bearing cap bolt.
(b) Install and uniformly tighten the 10 main bearing cap bolts.
Torque: 49 N Vm (500 kgf Vcm, 36 ft Vlbf)
(c) Check that the crankshaft turns smoothly.
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:2.440 ± 2.490 mm (0.0961 ± 0.0980 in.)
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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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20. INSTALL POWER STEERING (PS) SOLENOID VALVECONNECTOR
21. CONNECT ENGINE WIRE CONNECTORS
22. CONNECT THEFT DETERRENT HORN CONNECTOR
23. INSTALL GROUND CABLE TO BODY
24. CONNECT IGNITER CONNECTORS
(a) Connect the 2 igniter connectors HINT: Connect the yellow taped connector to the igniter on
the rear side.
(b) Install the wire clamp.
25. INSTALL RADIATOR ASSEMBLY
(a) Install the 2 lower radiator supports to the radiator.
(b) Place the radiator assembly on the body bracket.
(c) Slightly lift the radiator, and connect the 2 oil cooler hoses (for
cooling fan) to the hose clamp on the radiator fan shroud.
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(3) Two oil cooler hoses (for A/T) from radiator Plug thehose ends.
(4) Suction hose from hydraulic pump
(5) Pressure hose from hydraulic pump
(c) Re mo ve th e two bo lts, scre w an d u pper radiator
support. Remove the two upper radiator supports.
(d) Slightly lift the radiator, and d isconnect the two oil cooler
hoses (for cooling fan) from the hose clamp on the
radiator fan shrould.
(e) Remove the radiator.
14. DISCONNECT IGNITER CONNECTORS (a) Disconnect the two igniter connectors.
(b) Disconnect the wire clamp from the body.
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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.
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ENGINE MECHANICAL Cylinder Block
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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.
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3. PLACE CRANKSHAFT ON CYLINDER BLOCK
4. INSTALL MAIN BEARING CAP AND LOWER THRUSTWASHERS
A. Place main bearing cap and lower thrust washers on cyl-
inder block
(a) Install the two thrust washers on the No.3 main bearing cap with the grooves facing outward.
(b) Install the main bearing caps in their proper location.
(c) Place the five bearing caps in position on cylinder block.
HINT: Place the bearing caps level and let them return to their
original position by their own weight.
NOTICE: Do not install the main bearing cap by tapping
it.
B. Install main bearing cap nuts HINT:
wThe main bearing cap nuts are tightened in two
progressive steps (steps (b) and (d)).
w If any one of the main bearing cap stud bolts is broken
or deformed, replace it.
(a) Apply a light coat of engine oil on the threads and under
the nuts of the main bearing caps.
(b) Install and uniformly tighten the twenty main bearing cap
nuts in several passes in the sequence shown.
Torque: 27 N Vm (275 kgf Vcm, 20 ft Vlbf)
If any one of the main bearing cap nuts does not meet the
torque specification, replace the main bearing cap stud bolt.
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6. INSTALL CONNECTING ROD CAPS
A. Place connecting rod cap on connecting rod(a) Match the numbered c onnecting 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
cap.
(c) Check that the outside mark on the connecting rod cap is facing in correct direction.
B. Install connecting rod cap bolts HINT:
wThe connecting rod cap bolts are tightened in two
progressive steps (steps (b) and (d)).
w If any one of the connecting rod bolts is broken or
deformed, replace it.
(a) Apply a light of engine oil on the threads and under the
heads of the connecting rod cap bolts.
(b) Usin g SS T, in sta ll an d alte rn a te ly tig h te n th e two connecting rod cap bolts in several passes.
SST 09011±38121
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 bolt.
(c) Mark the front of the connecting rod cap bolt with paint.
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24. CONNECT IGNITER CONNECTOR(a) Connect the two igniter connectors.
(b) Install the wire clamp.
25. INSTALL RADIATOR (a) Install the two lower radiator supports to the radiator.
(b) Place the radiator on the body bracket.
(c) Slightly lift the radiator, and connect the two cooler hose(for cooling fan) to the hose clamp on the radiator fan
shrould.
(d) Install the upper radiator support with the two bolts and screw. Install the two upper radiator supports.
(e) Connect the following hoses: (1) Pressure hose to hydraulic pump
(2) Suction hose to hydraulic pump
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ENGINE MECHANICAL Cylinder Block
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The 1 UZ±FE engine has 8±cylinders in a V±arrangement at a bank an\
gle of 905. From the front of the RH
bank cylinders are numbered 2±4±6±8, and from the front of the LH b\
ank cylinders are numbered 1 ±3±5±7.
The crankshaft is supported by 5 bearings specified by the inside of the cr\
ankcase. These bearings are made
of a copper and lead alloy. The crankshaft is integrated with 8 weights which are cast along with it\
for balancing. Oil holes are built
into the center of the crankshaft for supplying oil to the connecting ro\
ds, pistons and other components. The ignition order is 1±8±4±3±6±5±7±2. The cylinder\
head is made of aluminum alloy, with a cross flow
type intake and exhaust layout and with pent±roof type combustion chambers. The spark plugs are loca\
ted in
the center of the combustion chambers.
At the front and rear of the intake manifold, a water passage has been p\
rovided which connects the RH
and LH cylinder heads. Exhaust and intake valves are equipped with irregular pitch springs made\
of special valve spring carbon
steel which are capable of following no matter what the engine speed.
The RH and LH intake camshafts are driven by a single timing belt, and a ge\
ar on the intake camshaft en-
gages with a gear on the exhaust camshaft to drive it. The camshaft jour\
nal is supported at 5 (intake) or 4 (ex-
haust) places between the valve lifters of each cylinder and on the front end of the cylinder \
head. Lubrication
of the cam journal gear is accomplished by oil being supplied through the \
oiler port in the center of the camshaft. Adjustment of the valve clearance is done by means of an outer shim type\
system, in which valve adjusting
shims are located above the valve lifters. This permits replacement of the sh\
ims without removal of the cam-
shafts. Pistons are made of high temperature±resistant aluminum alloy, and a depression is built into the piston
head to prevent interference with valves.
Piston pins are the full±floating type, with the pins fastened to neither the piston boss nor the connecting
rods. Instead, snap rings are fitted on both ends of the pins, preventing the\
pins from falling out. The No.1 compression ring is made of steel and the No.2 compression ring\
is made of cast iron. The oil
ring is m ade of a combination of steel and stainless steel. The outer diameter of\
each piston ring is slightly larger
than the diameter of the piston and the flexibility of the rings allows them\
to hug the cylinder walls when they
are mounted on the piston. Compression rings No.1 and No.2 work to prevent \
the leakage of gas from the cylin-
der and the oil ring works to scrape oil off the cylinder walls to prevent it from entering the combustion chamber. The cylinder block is made of aluminum alloy with a bank angle of 90 5. Cast iron cylinders are installed
inside the cylinder block. It has 8 cylinders which are approximately twice the length of th\
e piston stroke. The
top of each cylinder is closed off by the cylinder heads and the lower end of the cylinders becomes the crank-
case, in which the crankshaft is installed. In addition, the cylinder bl\
ock contains a water jacket, through which
coolant is pumped to cool the cylinders. The No.1 and No.2 oil pans are bolted onto the bottom of the cylinder block\
. The No.1 oil pan is made of
aluminum alloy. The No.2 oil pan is an oil reservoir made of pressed steel sheet. An o\
il level sensor is installed
in the No.1 oil pan (If the oil level drops below a set level, a warnin\
g light lights up.). A oil pan baffle plate keeps
sufficient oil in the bottom of the No.2 oil pan even when the vehicle is tilted. \
This dividing plate also prevents
the oil from making waves when the vehicle is stopped suddenly and the oil \
shifts away from the oil pump suction
pipe. Plastic region tightening bolts are used for the cylinder head, main bearing ca\
p and connecting rod.
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ENGINE MECHANICAL Operation
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