spark plugs LEXUS SC400 1991 Service Repair Manual

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 t\
he LH bank cylinders are 1 ± 3 ± 5 ± 7.
The crankshaft is supported by 5 bearings inside the crankcase. These beari\
ngs are made of a copper and
lead alloy.
The crankshaft is integrated with 8 weights for balance. Oil holes are plac\
ed in the center of the crankshaft
to supply oil to the connecting rods, bearing, pistons and other component\
s.
The ignition order is 1 ± 8 ± 4 ± 3 ± 6 ± 5 ± 7 ± 2. T\
he cylinder head is made of alminum alloy, with a cross
flow type intake and exhaust layout and with pent±roof type combustion chambers. The spark plugs are
located 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 functioning at all engine speeds.
The RH and LH intake camshaft are driven by a timing belt, and a gear on\
the intake camshaft engages
with a gear on the exhaust camshaft to drive it. The cam journal is supp\
orted at 5 (intake) or 4 (exhaust)
places between the valve lifters of each cylinder and on the front end o\
f the cylinder head. Lubrication of
the cam journals and gears is accomplished by oil being supplied through th\
e 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
camshafts.
Pistons are made of high temperature±resistant aluminum alloy, and a depression is built into the piston
head to prevent interference with the 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 made of a combination of steel and stainless steel. The outer diamet\
er 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 gas leakage from
the cylinder and the oil ring works to scrape oil off the cylinder walls to prevent it from entering the combus-
tion chambers.
The cylinder block is made of aluminum alloy with a bank of 90 5. Cast iron cylinders are installed inside
the cylinder block. It has 8 cylinders which are approximately twice the le\
ngth of the piston stroke. The top
of each cylinder is closed off by the cylinder head and the lower end of the cylinders becomes the crank-
case, in which the crankshaft is installed. In addition, the cylinder block c\
ontains 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 bl\
ock. 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 oil level drops below a set level, a warning light\
s up.). And oil pan baffle plate
keeps sufficient oil in the bottom of the No.2 oil pan even when the vehicle is t\
ilted. This dividing plate also
prevents the oil from marking waves when the vehicle is stopped suddenly\
and the oil shifts away from the
oil pump suction pipe.
Plastic region tighten bolts are used for the cylinder head, main bearin\
g cap and connecting rod.
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1UZ±FE ENGINE ENGINE MECHANICAL
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(e) Disconnect the 4 high±tension cords together with the frontand rear high±tension cord clamps from the spark plugs.
NOTICE: Pulling on or bending the cords may damage the con-
ductor inside.
(f) Remove the 8 bolts, seal washers, cylinder head cover and gasket.
18. REMOVE LH CYLINDER HEAD COVER
(a) Disconnect the No.1 high±tension cord from the cord clamp on the front high±tension cord clamp.
(b) Remove the 2 bolts holding the high±tension cord clamps to the cylinder head cover.
(c) Disconnect the 5 high±tension cords from the front side of the
front high±tension cord clamp.
(d) Disconnect the front high±tension cord clamp from the lower high±tension cord cover.
(e) Disconnect the 4 high±tension cords together with the front and rear high±tension cord clamps from the spark plugs.
NOTICE: Pulling on or bending the cords may damage the con-
ductor inside.
(f) Disconnect the engine wire protector from the 2 brackets on the delivery pipe.
(g) Disconnect the 4 injector connectors.
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1UZ±FE ENGINE ENGINE MECHANICAL
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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 old 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 bolt.
(e) Install the cylinder head cover with the 8 bolts.
Torque: 5.9 N Vm (60 kgf Vcm, 52 in. Vlbf)
(f) Connect the 4 high±tension cords to the spark plugs.
(g) Connect the front high±tension cord clamp to the lower
high±tension cord cover.
(h) P l a c e t h e f r o n t h i gh±tension cord clamp to the rear
high±tension cord clamp.
(i) Install the 2 bolts holding the high±tension cord clamps to the
cylinder head cover.
(j) Connect the 5 high±tension cords to the front side of the front
high±tension cord clamp.
(k) Connect the No. 2 high±tension cord to the cord clamp on the
front high±tension cord clamp.
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1UZ±FE ENGINE ENGINE MECHANICAL
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25. REINSTALL LH CYLINDER HEAD COVER
(a) Remove any old 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 bolt.
(e) Install the cylinder head cover with the 8 bolts.
Torque: 5.9 N Vm (60 kgf Vcm, 52 in. Vlbf)
(f) Connect the 2 engine wire connectors.
(g) Connect the 4 injector connectors.
(h) Install the engine wire protector to the 2 brackets on the
delivery pipe.
(i) Connect the 4 high±tension cords to the spark plugs.
(j) Connect the front high±tension cord clamp to the lower high±tension cord cover.
(k) P l a c e t h e f r o n t h i gh±tension cord clamp to the rear
high±tension cord clamp.
(l) Install the 2 bolts holding the high±tension cord clamps to the
cylinder head cover.
(m) Connect the 5 high±tension cords to the front side of the front
high±tension cord clamp.
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1UZ±FE ENGINE ENGINE MECHANICALEG±27
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10. DISCONNECT COLD START INJECTOR CONNECTOR
11. DISCONNECT RH CAMSHAFT POSITION SENSORCONNECTOR
(a) Disconnect the connector from the ignition coil bracket.
(b) Disconnect the camshaft position sensor connector.
12. D I S C O N N E C T L H C A M S H A F T P O S I T I O N S E N S O R
CONNECTOR
13. DISCONNECT HIGH±TENSION CORDS FROM SPARK PLUGS
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 con-
ductor inside.
14. REMOVE SPARK PLUGS Using a 16 mm plug wrench, remove the 8 spark plugs.
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1UZ±FE ENGINE ENGINE MECHANICALEG±39
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15. CHECK CYLINDER COMPRESSION PRESSURE
(a) Reconnect the battery negative (±) cable.
(b) Insert a compression gauge into the spark plug hole.
(c) Fully open the throttle.
(d) Wh ile cra n kin g th e en g in e , me a su re th e co mp re ssio npressure.
HINT: Always use a fully charged battery to obtain engine
speed of 250 rpm or more.
(e) Repeat steps (b) through (d) for each cylinder. NOTICE: This measurement must be done in as short a
time as possible.
Compression pressure:
1,226 kPa (12.5 kgf/cm
2, 178 psi) or more
Minimum pressure: 981 kPa (10.0 kgf/cm
2, 142 psi)
Difference between each cylinder: 98 kPa (1.0 kgf/cm
2, 14 psi) or less
(f) If the cylinder compression in one or more cylinders is low,pour a sm all amount of engine oil into the cylinder through the
spark plug hole and repeat steps (b) through (d) for cylinders
with low compression.
w If adding oil helps the compression, it is likely that the
piston rings and/or cylinder bore are worn or damage.
w If pressure stays low, a valve may be sticking or seating
is improper, or there may be leakage past the gasket.
(g) Disconnect the battery negative (±) cable.
16. REINSTALL SPARK PLUGS
Using a 16 mm plug wrench, install the 8 spark plugs.
Torque: 18 N Vm (180 kgf Vcm, 13 ft Vlbf)
17. 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
18. RECONNECT RH CAMSHAFT POSITION SENSOR CONNECTOR
(a) Connect the camshaft position sensor connector.
(b) Install the camshaft position sensor connector to the ignition
coil bracket.
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1UZ±FE ENGINE ENGINE MECHANICAL
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25. REMOVE SPARK PLUGSUsing a 16 mm plug wrench, remove the 8 spark plugs.
26. IF RE±USING TIMING BELT, CHECK INSTALLATION MARKS ON TIMING BELT
Check that there are 4 installation marks on the timing belt by
turning the crankshaft pulley as shown in the illustration.
HINT: If the installation marks have disappeared, place a new
installation mark on the timing belt before removing each
part.
27. SET NO.1 CYLINDER TO TDC/COMPRESSION
(a) Turn the crankshaft pulley and align its groove with timing mark ª0º of the No.1 timing belt cover.
(b) Check that the timing marks of the camshaft timing pulleys and timing belt rear plates aligned.
If not, turn the crankshaft 1 revolution (360 5).
28. REMOVE TIMING BELT TENSIONER HINT:
wWhen re±using timing belt:
If the installation marks have disappeared, before re-
move the timing belt, place new installation marks on
the timing belt to match the timing marks of the camshaft
timing pulleys, and place the a new installation mark on
the timing belt to match the end of the hydraulic pump.
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1UZ±FE ENGINE ENGINE MECHANICALEG±53
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16. INSTALL TIMING BELT TENSIONER
(a) Temporarily install the belt tensioner with the 2 bolts.
(b) Alternately tighten the 2 bolts.
Torque: 26 NVm (270 kgf Vcm, 20 ft Vlbf)
(c) Using pliers, remove the 1.27 mm hexagon wrench from the
belt tensioner.
17. CHECK VALVE TIMING
(a) Slowly turn the crankshaft pulley 2 revolutions from TDC to TDC.
NOTICE: Always turn the crankshaft pulley clockwise.
(b) Check that each pulley aligns with the timing marks as shown
in the illustration.
If the timing marks do not align, remove the timing belt and
reinstall it.
18. INSTALL SPARK PLUGS Using a 16 mm plug wrench, install the 8 spark plugs.
Torque: 18 N Vm (180 kgf Vcm, 13 ft Vlbf)
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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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