1991 LEXUS SC300 spark plugs

27. INSTALL DRIVE BELT IDLER PULLEYInstall the idler pulley and cover plate with the bolt.
Torque: 37 N Vm (380 kgf Vcm, 27 ft Vlbf)
28. INSTALL HIGH±TENSION CORDS, CORD CLAMPS AND
CORD COVER ASSEMBLY
(a) C onnect the high±tension cords to the spark plugs,
distributor caps and RH ignition coil.
(b) Install the lower high±tension cord cover with the bolt.
(c) Connect the RH front high±tension cord clamp to the lower high±tension cord cover.
(d) Place the RH front high±tension cord clamp to the RH rear
high±tension cord clamp.
(e) Install the 2 bolts holding the RH high±tension cord clamps to the RH cylinder head cover.
(f) Connect the No.2 high±tension cord to the cord clamp on the
RH front high±tension cord clamp.
(g) Connect the LH front high±tension cord clamp to the lower high±tension cord cover.
(h) Place the LH front high±tension cord clamp to the LH rear
high±tension cord clamp.
(i) Install the 2 bolts holding the LH high±tension cord clamps to the LH cylinder head cover.
(j) Connect the No.1 high±tension cord to the cord clamp on the
LH front high±tension cord clamp.
29. INSTALL RH NO.3 TIMING BELT COVER
(a) Install the 3 gaskets to the timing belt cover.
(b) Fit the portion A of the timing belt cover, matching it with the lower high±tension cord cover.
(c) Install the timing belt cover with the 4 bolts.
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1UZ±FE ENGINE ENGINE MECHANICALEG±67
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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.
EM±4
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ENGINE MECHANICAL Operation
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6. REMOVE THROTTLE BODY WITH INTAKE AIRCONNECTOR
(a) Disconnect the following hoses and connectors:(1) PCV hose
(2) Three vacuum hoses
(3) VSV (for EGR) connector
(4) Throttle position sensor connector
(5) IAC valve connector
(6) (w/ TRAC)
Sub±throttle position sensor connector
(7) (w/ TRAC) Sub±throttle actuator connector
(8) (USA spec. only)
EGR gas temperature sensor connector
(b) Remove the four bolts and two nuts holding the intake air connector to the intake chamber.
(c) Remove the VSV nut.
(d) Disc onnect the two water by±pass hoses from the
throttle body. Plug the hose ends.
(e) Remove the throttle body with the intake air connector and gasket.
7. REMOVE NO. 3 TIMING BELT COVER AND CYLINDER
HEAD REAR COVER
(a) Remove the oil filler cap.
(b) Using a 5 mm hexagon wrench, remove the ten bolts,No. 3 timing belt cover and cylinder head rear cover.
8. DISCONNECT HIGH±TENSION CORDS FROM SPARK PLUGS
(a) Remove the bolt holding the cord clamp from thecylinder head.
(b) Disconnect the two high±tension cord clamps from the No. 3 cylinder head cover.
(c) Disconnect the high±tension cords at the rubber boot. Do not pull on the cords.
NOTICE: Pulling on or bending the cords may damage
the conductor inside.
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ENGINE MECHANICAL Engine Tune±UpEM±11
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13. REINSTALL NO. 3, NO. 1 AND NO. 2 CYLINDER HEADCOVERS
(a) Remove any oil packing (FIPG) material.
(b) Apply seal packing to the cylinder head as shown in theillustration.
Seal packing: Part No. 08826±00080 or equivalent
(c) Install the gaskets to the No. 1 and No. 2 cylinder headcovers.
(d) Install the cylinder head cover with the 12 bolts and four
nuts.
Torque: 5.4 N Vm (55 kgf Vcm, 48 in. Vlbf)
14. R E C O N N E C T H I G H ± T E N S I O N C O R D S TO S PA R K
PLUGS
(a) Connect the high±tension cord to the spark plug.
HINT: The No. 4 high±tension cord must be raised 10 5 from
the perpendicular line.
(b) Connect the two high±tension cord clamps to the No. 3 cylinder head cover.
(c) Install the high±tension cord clamp with the bolt.
15. REINSTALL CYLINDER HEAD REAR COVER AND NO. 3 TIMING BELT COVER
(a) Using a 5 mm hexagon wrench, install the cylinder head
rear cover and No. 3 timing belt cover with the ten bolts.
(b) Install the oil filler cap.
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ENGINE MECHANICAL Engine Tune±UpEM±17
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(c) Remove the two bolts and two nuts, disconnect thethrottle body from the air intake chamber.
(d) Disconnect the following hoses, and remove the throttle body:
(1) PCV hose from throttle body
(2) Water by±pass hose from throttle body
(e) Remove the throttle body gasket.
17. REMOVE RH CYLINDER HEAD COVER (a) Remove the two bolts holding the cord clamp to thecylinder head.
(b) Disc onnect the high±tension cords from the spark
plugs.
(c) Disconnect the high±tension cords from the front high±tension cord clamp.
(d) Remove the eight bolts, seal washers, cylinder head cover and gasket.
EM±14
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ENGINE MECHANICAL Engine Tune±Up
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16. REMOVE LH CYLINDER HEAD COVER(a) Remove the two bolts holding the high±tension cordclamp to the cylinder head.
(b) Disc onnect the high±tension cords from the spark
plugs.
(c) Disconnect the high±tension cords from the front high±tension cord clamp.
(d) Disconnect the engine wire from the two wire clamps on
the LH delivery pipe.
(e) Disconnect the four injector connectors.
(f) Disconnect the two engine wire connectors.
(g) Remove the eight bolts, seal washers, cylinder head
cover and gasket.
19. SET NO.1 CYLINDER TO TDC/COMPRESSION (a) Turn the crankshaft pulley, and align its groove with thetiming mark º0º of the No.1 timing belt cover.
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ENGINE MECHANICAL Engine Tune±UpEM±15
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23. REINSTALL THEFT DETERRENT HORN(a) Install the theft deterrent horn with the bolt.
(b) Connect the connector.
24. REINSTALL RH CYLINDER HEAD COVER (a) Remove any oil packing (FIPG) material.
(b) Apply seal packing to the cylinder head as shown in theillustration.
Seal packing: Part No. 08826±00080 or equivalent
(c) Install the gasket to the cylinder head cover.
(d) Install the seal washer to the mounting bolt.
(e) Install the cylinder head cover with the eight bolts.
Torque: 5.9 N Vm (60 kgf Vcm, 52 in. Vlbf)
(g) Connect the four high±tension cords to the spark plugs.
(h) Install the rear and front high±tension cord clamps with
the two bolts.
HINT: Place the front and rear ends of the front high±tension
cord clamp on the rear high±tension cord clamp and lower
high±tension cord cover.
(i) Fit the high±tension cords to the high±tension cord clamps. (See page IG±16)
25. REINSTALL LH CYLINDER HEAD COVER (a) Remove any oil packing (FIPG) material.
(b) Apply seal packing to the cylinder head as shown in theillustration.
Seal packing: Part No. 08826±00080 or equivalent
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ENGINE MECHANICAL Engine Tune±Up
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(c) Install the gasket to the cylinder head cover.
(d) Install the seal washer to the mounting bolt.
(e) Install the cylinder head cover with the eight bolts.
Torque: 5.9 NVm (60 kgf Vcm, 52 in. Vlbf)
(f) Connect the two engine wire connectors.
(g) Connect the four injector connectors.
(h) Install the engine wire to the two wire clamps on the
delivery pipe.
(i) Connect the four high±tension cords to the spark plugs.
(j) Install the rear and front high±tension cord clamps with the two bolts.
HINT: Place the front and rear ends of the front high±tension
cord clamp on the rear high±tension cord clamp and lower
high±tension cord cover.
(k) Fit the high±tension cords to the high±tension cord clamps. (See page IG±16)
26. REINSTALL THROTTLE BODY (a) Connect the following hoses:(1) PCV hose from throttle body
(2) Water by±pass hose from throttle body
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ENGINE MECHANICAL Engine Tune±UpEM±23
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