Lexus SC300 / Lexus SC400. Service manual — part 414

INSPECTION OF BATTERY

1. INSPECT BATTERY SPECIFIC GRAVITY AND

ELECTROLYTE LEVEL
(a) Check the specific gravity of each cell.

Standard specific gravity:

1.250–1.270 when fully charged at 20

°

C (68

°

F)

If not within specification, charge the battery.
(b) Check the electrolyte level of each cell.
If insufficient, refill with distilled (or purified) water.

2. CHECK

BATTERY

TERMINALS

Check the battery terminals for looseness or corrosion.

INSPECTION AND CLEANING OF AIR
FILTER

1.

REMOVE AIR FILTER
(a) Open the air cleaner cap.

(b) Remove the air filter.

2.

INSPECT AIR FILTER
(a) Visually check that the air filter is not excessively

damaged or oily.

(b) Clean the air filter with compressed air. First blow from

the inside thoroughly, then blow off the outside of the air
filter.

3. REINSTALL

AIR

FILTER

EM–8

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ENGINE MECHANICAL

Engine Tune–Up

INSPECTION OF HIGH–TENSION CORDS
INSPECT HIGH–TENSION CORD
RESISTANCE

(See page IG–7)

Maximum resistance: 25 K

per cord

INSPECTION OF DRIVE BELT

INSPECT DRIVE BELT

HINT: A belt tensioner is used, so checking the belt tension
is not necessary.
(a) Visually check the drive belt for excessive wear, frayed

cords etc.

If necessary, replace the drive belt.
HINT: Cracks on rib side of a drive belt are considered accept-
able. If the drive belt has chunks missing from the ribs, it
should be replaced.
(b) Check the belt tensioner operation.

•

Check that the belt tensioner moves downward
when the drive belt is pressed down at the points
indicated in the illustration with approx. 98 N (10
kgf, 22.0 lbf) of force.

•

Check the alignment of the belt tensioner pulley to
make sure the drive belt has not slipped off the
pulley.

If necessary, replace the belt tensioner.

•

Check that the arrow mark on the belt tensioner
falls within area A of the scale.

If it is outside area A, replace the drive belt.
HINT:

•

When a new belt is installed, it should lie within area B.
If not, the drive is not correct.

•

After installing a belt, check that it fits properly in the
ribbed grooves.

•

Check by hand to confirm that the belt has not slipped
out of the groove on the bottom of the pulley.

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ENGINE MECHANICAL

Engine Tune–Up

EM–9

INSPECTION AND ADJUSTMENT OF
VALVE CLEARANCE

HINT: Inspect and adjust the valve clearance when the en-
gine is cold.

1.

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Turn the ignition switch to ”LOCK”. Discon-
nect the cable from the negative (–) terminal of the bat-
tery. Wait at least 20 seconds before procceding with
work.

2. DISCONNECT CONTROL CABLES FROM THROTTLE

BODY
Disconnect the following cables:

(1) Accelerator cable
(2) (A/T) Throttle control cable
(3) Cruise control actuator cable

3.

REMOVE AIR CLEANER HOSE
(a) Disconnect the following hoses:

(1) PS air hose from No.

4 timing belt cover

(2) PCV hose from No.

2 cylinder head cover

(b) Loosen

the two hose clamps and remove the air cleaner

hose.

4.

REMOVE EGR PIPE
(a) Loosen the union nut.
(b) Remove the two bolts, EGR pipe and gasket.

5.

REMOVE THROTTLE BODY BRACKET
Remove the four nuts and throttle body bracket.

EM–10

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ENGINE MECHANICAL

Engine Tune–Up

6. REMOVE THROTTLE BODY WITH INTAKE AIR

CONNECTOR
(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) Disconnect 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 the

cylinder 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–Up

EM–11