1991 LEXUS SC400 compression ratio

22. REMOVE ALTERNATOR(a) Disconnect the alternator connector.
(b) Remove the cap and nut, and disconnect the alternatorwire.
(c) Remove the bolt, and disconnect the A/T oil cooler pipe bracket.
(d) Remove the nut and alternator.
23. REMOVE DRIVE BELT TENSIONER Remove the bolt, two nuts and tensioner.
24. REMOVE SPARK PLUGS Using a 16 mm plug wrench, remove the eight spark plugs.
25. IF RE±USING TIMING BELT, CHECK INSTALLATION MARKS ON TIMING BELT
Check that there are four installation marks on the timing belt
by turning the crankshaft pulley as shown in the illustration.
If the installation marks have disappeared, place a new
installation mark on the timing belt before removing each
part.
26. SET NO.1 CYLINDER TO TDC/COMPRESSION (a) Turn the crankshaft pulley and align its groove with thetiming mark ºOº of the No.1 timing belt cover.
EM±40
±
ENGINE MECHANICAL Timing Belt
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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
±
ENGINE MECHANICAL Operation
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EQUIPMENT
 


Part Name\
 
\

\
Note
 Caliper gauge\
 \

 


HC/CO meter
\
 
\

\

 


Compression gauge\
 
\

\
Cylinder compression pressure
 Connecting rod aligner\
 \

 


Cylinder gauge
\
 
\

\

 


Dial indicator
\
 
\

\

 


Engine turn±up tester\
 
\

\

 Feeler gauge\
 \

 


Micrometer
\
 
\

\

 


Precision straight edge\
 
\

\

 Spring tester\
 \
Valve spring
 


Steel square
\
 
\

\
Valve spring
 


Torque wrench\
 
\

\

 Vernier caliper\
 \

SSM (SPECIAL SERVICE MATERIALS)
 
Part Name
 
Part No.
\
 \

Use etc.  \
 \

Camshaft bearing cap  \
 \
Camshaft bearing ca
Cylinder head semi±circular plug 
Seal packing or equivalent
 
08826±00080
\
 \
Cylinder head semi±circular lug
Cylinder head cover Seal acking or equivalent 08826±00080\
 \
Cylinder head cover
Rear oil seal retainer  \
 \
Rear oil seal retainer
Oil pump  \
 \

Water inlet housing Seal packing 1282B,
Th b d 1282B i l t
 08826±00100\
 \
Water inlet housing
Water seal plate Three bond 1282B or equivalent 08826±00100\
 \
Water seal late
Water pump 

Adhesive 1324,
Three bond 1324 or equivalent
 

08833±00070
\
 

\
Drive plate mounting bolt
 
Adhesive 1344,
 \
 \

 Adhesive 1344,
Three bond 1344
,
 
08833±00080
\
 \

No.1 idler pulley mounting bolt Three bond 1344,
Loctite 242 or equivalent 08833±00080\
 \
No.1 idler ulley mounting bolt
±
ENGINE MECHANICAL PreparationEM±7
WhereEverybodyKnowsYourName

TORQUE SPECIFICATIONS
SR0GQ±01\
 \
Part tightened NVm kgf Vcm ft Vlbf\
 \
STEERING COLUMN   
\
 \
Steering wheel 35 360 26\
 \
Steering wheel pad 7.4 75 65 in. Vlbf\
 \
Column bracket X Body 25 260 19\
 \
Sliding yoke 35 360 26\
 \
(Power tilt and power telescopic steering column)   
\
 \
Tilt steering housing support X Lower tube 13 130 9\
 \
Support stopper bolt lock nut 2.9 30 26 in. Vlbf\
 \
Connector bracket 4.9 50 43 in. Vlbf\
 \
Telescopic sensor plate 4.9 50 43 in. Vlbf\
 \
Telescopic adjusting screw 6.9 70 61 in. Vlbf\
 \
Telescopic adjusting screw lock nut 31 320 23\
 \
(Manual tilt and Manual telescopic steering column)   
\
 \
Tilt memory bolt 6.4 65 56 in. Vlbf\
 \
Tilt memory bolt set nut 5.9 60 52 in. Vlbf\
 \
Tilt lever assembly installation bolt 2.9 30 26 in. Vlbf\
 \
Tilt pawl set nut 5.9 60 52 in. Vlbf\
 \
Tilt lever retainer set nut 15 150 11\
 \
Compression spring bushing bolt 7.8 80 69 in. Vlbf\
 \
Steering column tube stopper bolt 19 195 14\
 \
Serration attachment set nut 13 130 9\
 \
Telescopic lever set bolt 25 260 19\
 \
Connector bracket set bolt 4.9 50 43 in. Vlbf\
 \
POWER STEERING PUMP   
\
 \
(SC 400)   
\
 \
PS pump installation bolt 39 400 29\
 \
PS pump installation nut 43 440 32\
 \
Pressure tube X Pressure port union 49 500 36\
 \
Drive pulley X Rotor shaft 43 440 32\
 \
Front housing X Rear bracket 39 400 29\
 \
Pressure port union X Pump housing 69 700 51\
 \
Suction port union X Pump housing 13 130 9\
 \
(SC 300)   
\
 \
PS pump installation bolt 58 590 43\
 \
Pressure tube X Pressure port union 49 500 36\
 \
Drive pulley X Rotor shaft 43 440 32\
 \
Front housing X Rear housing 17 170 12\
 \
Pressure port union X Pump housing 83 850 61\
 \
Reservoir tank X Pump housing Front side bolt 13 130 9\
 \
Rear side bolts 17 170 12
±
STEERING SERVICE SPECIFICATIONSSR±171
WhereEverybodyKnowsYourName

5. REMOVE TURN SIGNAL BRACKET
6. REMOVE PROTECTOR
7. REMOVE CONNECTOR BRACKET
8. REMOVE TELESCOPIC LEVER SERRATIONATTACHMENT
Remove the nut and the serration attachment.
9. REMOVE TELESCOPIC LEVER
(a) Remove the bolt, collar, lever and washer.
(b) Remove the ball and compression spring.
±
STEERING STEERING COLUMNSR±15
WhereEverybodyKnowsYourName

(c) Using snap ring pliers, install the snap ring to the main shaft.
(d) Install the steering column tube stopper bolt.
Torque: 19 NVm (195 kgf Vcm, 14 ft Vlbf)
16. INSTALL TELESCOPIC LEVER LOCK BOLT
(a) Pull the steering column tube away from the breakaway
bracket and facing the body installation surface of the
breakaway bracket upward, temporarily install the lock bolt.
(b) Install a double nut on the lock bolt. Torque to 16 N Vm (160 kgf Vcm, 12 ft Vlbf), loosen once, then
torque again to 7.4 N Vm (75 kgf Vcm, 65 in. Vlbf).
17. INSTALL TELESCOPIC LEVER
(a) Install the compression spring and ball.
(b) Install the washer, lever, collar and bolt.
Torque: 25 N Vm (260 kgf Vcm, 19 ft Vlbf)
18. I N S TA L L T E L E S C O P I C L EVER SERRATION
ATTACHMENT
(a) Rotate the telescopic lever until it touches the breakaway
bracket.
(b) Install the serration attachment so that the alignment marks on the telescopic lever and the serration attachment align.
Torque: 13 N Vm (130 kgf Vcm, 9 ft Vlbf)
SR±24±
STEERING STEERING COLUMN
WhereEverybodyKnowsYourName

Diag Code 25 26

Air±Fuel Ratio Lean Malfunction
Diag. Code 25, 26
Air±Fuel Ratio Rich Malfunction
CIRCUIT DESCRIPTION
Refer to page TR±62 for the circuit description.
Code No.
Diagnostic Code Detecting SystemTrouble Area
(1) Main oxygen sensor voltage is 0.45 V or less (lean) for 90 sec. under conditions
(a) and (b).
(2 trip detection logic)
*2
(a) Coolant temp.: 70 °C (158 °F)
or more.
(b) Engine speed: 1,500 rpm or more.
 Open or short in main oxygen sensor
circuit
 Main oxygen sensor
 Ignition system
 ECU
25
(2)*1 Difference of air±fuel ratio feedback
compensation value between front (No.
1 3 cylinders) and rear (No. 4 6
cylinders) is more than 15 percentage
for 20 sec. or more under conditions (a)
and (b).
(2 trip detection logic)
*2
(a) Engine speed: 2,000 rpm or more.
(b) Coolant temp.: Between 60 °C
(140 °F) and 95 °C (203 °F).
 Open and short in injector circuit.
 Fuel line pressure (injector leak, blockage)
 Mechanical system malfunction (skipping
teeth of timing belt)
 Ignition system
 Compression pressure (foreign object
caught in valve)
 Air flow meter (air intake)
 ECU
(3)*1 Engine speed varies by more than 15
rpm over the preceding crank angle period
during a period of 20 sec. or more under
conditions (a) and (b).
(2 trip detection logic)
*2
(a) Engine speed: Idling
(b) Coolant temp.: Between 60 °C
(140 °F) and 95 °C (203 °F).
 Open and short in injector circuit.
 Fuel line pressure (injector leak, blockage)
 Mechanical system malfunction (skipping
teeth of timing belt)
 Ignition system
 Compression pressure (foreign object
caught in valve)
 Air flow meter (air intake)
 ECU
26*1
(1) Difference of air±fuel ratio feedback
compensation value between front (No. 1
3 cylinders) and rear (No.4 6 cylinders) is
more than 15 percentage for 20 sec. or
more under conditions (a) and (b).
(2 trip detection logic)
*2
(a) Engine speed: 2,000 rpm or more.
(b) Coolant temp.: Between 60 °C
(140 °F) and 95 °C (203 °F).
 Open and short in injector circuit.
 Fuel line pressure (injector leak, blockage)
 Mechanical system malfunction (skipping
teeth of timing belt)
 Ignition system
 Compression pressure (foreign object
caught in valve)
 Air flow meter (air intake)
 ECU
261
(2) Engine speed varies by more than 15
rpm over the preceding crank angle peri-
od during a period of 20 sec. or more un-
der conditions (a) and (b).
(2 trip detection logic)
*2
(a) Engine speed: Idling
(b) Coolant temp.: Between 60 °C
(140 °F) and 95 °C (203 °F).
 Open and short in injector circuit.
 Fuel line pressure (injector leak, blockage)
 Mechanical system malfunction (skipping
teeth of timing belt)
 Ignition system
 Compression pressure (foreign object
caught in valve
 Air flow meter (air intake)
 ECU
*1: Only for USA specification vehicles.
*2: See page TR±25.
TR±70
±
ENGINE TROUBLESHOOTING Circuit Inspection
WhereEverybodyKnowsYourName

Diag Code 25 26

Air±Fuel Ratio Lean Malfunction
Diag. Code 25, 26
Air±Fuel Ratio Rich Malfunction
CIRCUIT DESCRIPTION
Refer to page TR±62 for the circuit description.
Code No.
Diagnostic Code Detecting SystemTrouble Area
(1) Main oxygen sensor voltage is 0.45 V or less (lean) for 90 sec. under conditions
(a) and (b).
(2 trip detection logic)
*2
(a) Coolant temp.: 70 °C (158 °F)
or more.
(b) Engine speed: 1,500 rpm or more.
 Open or short in main oxygen sensor
circuit
 Main oxygen sensor
 Ignition system
 ECU
25
(2)*1 Difference of air±fuel ratio feedback
compensation value between front (No.
1 3 cylinders) and rear (No. 4 6
cylinders) is more than 15 percentage
for 20 sec. or more under conditions (a)
and (b).
(2 trip detection logic)
*2
(a) Engine speed: 2,000 rpm or more.
(b) Coolant temp.: Between 60 °C
(140 °F) and 95 °C (203 °F).
 Open and short in injector circuit.
 Fuel line pressure (injector leak, blockage)
 Mechanical system malfunction (skipping
teeth of timing belt)
 Ignition system
 Compression pressure (foreign object
caught in valve)
 Air flow meter (air intake)
 ECU
(3)*1 Engine speed varies by more than 15
rpm over the preceding crank angle period
during a period of 20 sec. or more under
conditions (a) and (b).
(2 trip detection logic)
*2
(a) Engine speed: Idling
(b) Coolant temp.: Between 60 °C
(140 °F) and 95 °C (203 °F).
 Open and short in injector circuit.
 Fuel line pressure (injector leak, blockage)
 Mechanical system malfunction (skipping
teeth of timing belt)
 Ignition system
 Compression pressure (foreign object
caught in valve)
 Air flow meter (air intake)
 ECU
26*1
(1) Difference of air±fuel ratio feedback
compensation value between front (No. 1
3 cylinders) and rear (No.4 6 cylinders) is
more than 15 percentage for 20 sec. or
more under conditions (a) and (b).
(2 trip detection logic)
*2
(a) Engine speed: 2,000 rpm or more.
(b) Coolant temp.: Between 60 °C
(140 °F) and 95 °C (203 °F).
 Open and short in injector circuit.
 Fuel line pressure (injector leak, blockage)
 Mechanical system malfunction (skipping
teeth of timing belt)
 Ignition system
 Compression pressure (foreign object
caught in valve)
 Air flow meter (air intake)
 ECU
261
(2) Engine speed varies by more than 15
rpm over the preceding crank angle peri-
od during a period of 20 sec. or more un-
der conditions (a) and (b).
(2 trip detection logic)
*2
(a) Engine speed: Idling
(b) Coolant temp.: Between 60 °C
(140 °F) and 95 °C (203 °F).
 Open and short in injector circuit.
 Fuel line pressure (injector leak, blockage)
 Mechanical system malfunction (skipping
teeth of timing belt)
 Ignition system
 Compression pressure (foreign object
caught in valve
 Air flow meter (air intake)
 ECU
*1: Only for USA specification vehicles.
*2: See page TR±25.
TR±70
±
ENGINE TROUBLESHOOTING Circuit Inspection
WhereEverybodyKnowsYourName