Lexus SC300 / Lexus SC400. Manual — part 417

ENGINE TUNE–UP

INSPECTION OF ENGINE COOLANT

1. INSPECT

ENGINE

COOLANT

LEVEL

AT

RESERVOIR

TANK
The coolant level should be above the ”COLD LEVEL” at
normal temperature (20

°

C (68

°

F)).

If low, check for leaks and add coolant up to the ”COLD
LEVEL”.

2.

INSPECT ENGINE COOLANT QUALITY
There should be any excessive deposits of rust or scales
around the radiator cap or reservoir tank filler hole, and the
coolant should be free from oil.
If excessively dirty, clean the coolant passages and replace
the coolant.

INSPECTION OF ENGINE OIL

1.

INSPECT ENGINE OIL QUALITY
Check the oil for deterioration, entry of water, discoloring or
thinning.
If the quality is poor, replace the oil.

Oil grade: API grade SG, Energy–Conserving II multigrade.

Recommended viscosity is as shown, with SAE

5W–30 being the preferred engine oil.

Drain and refill oil capacity:

w/ oil filter change

4.8 liter (5.1 US qts, 4.2 lmp. qts)

w/o oil filter change

4.5 liter (4.8 US qts, 4.0 lmp. qts)

2.

INSPECT ENGINE OIL LEVEL
The oil level should be between the ”L” and ”F” marks on the
dipstick.
If low, check for leakage and add oil up to ”F” mark.

EM–8

–

ENGINE MECHANICAL

Engine Tune–Up

INSPECTION OF BATTERY

1. INSPECT BATTERY SPECIFIC GRAVITY AND

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

Standard specific gravity:

1.27–1.29 when fully charged at 20

°

C(68

°

F)

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

2. CHECK

BATTERY

TERMINALS

Check that the battery terminals are not loose or corroded.

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 out-
side of the air filter.

3.

REINSTALL AIR FILTER

–

ENGINE MECHANICAL

Engine Tune–Up

EM–9

INSPECTION OF HIGH–TENSION CORDS

1.

REMOVE HIGH–TENSION CORDS (See page

IG–11

)

2.

INSPECT HIGH–TENSION CORDS
(b) Using an ohmmeter, measure the resistance.

Maximum resistance: 25 k

per cord

If the resistance is greater than maximum, replace the cord.

3.

REINSTALL HIGH–TENSION CORDS (See page

IG–16

)

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
acceptable. If the drive belt has chunks missing from the
ribs, it should be replaced.

•

The drive belt tension can be released by turning the
belt tensioner counterclockwise. The pulley bolt for the
belt tensioner has a left–hand thread.

(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 belt 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.

EM–10

–

ENGINE MECHANICAL

Engine Tune–Up

INSPECTION AND ADJUSTMENT OF
VALVE CLEARANCE

HINT: Inspect and adjust the valve clearance when the
engine is cold.

1.

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Work must be started after approx. 20 se-
conds or longer from the time the ignition switch is
turned to the ”LOCK” position and the negative (–) termi-
nal cable is disconnected from the battery.

2.

DRAIN ENGINE COOLANT (See page

CO–6

)

3.

REMOVE THROTTLE BODY COVER
(a) Remove the mounting cap nut.
(b) Loosen the two bolts, and remove the throttle body

cover.

4. DISCONNECT CONTROL CABLES FROM THROTTLE

BODY
Disconnect the following cables:

(1)

Accelerator cable

(2)

A/T throttle control cable

(3)

(w/ Cruise Control System)
Cruise control actuator cable

5.

REMOVE INTAKE AIR CONNECTOR
(a) Disconnect the following hoses:

(1)

Air hose from ISC valve

(2)

Air hose (from PS air control valve) from intake
air connector

(b) Remove the bolt holding the intake air connector to

the cylinder head cover.

(c) Loosen the two hose clamps.
(d) Disconnect the intake air connector from the throttle

body and air cleaner hose, and remove the throttle body.

–

ENGINE MECHANICAL

Engine Tune–Up

EM–11