Lexus SC300 / Lexus SC400. Manual - part 553

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

6. 

REMOVE UPPER HIGH–TENSION CORD COVER
(a)  Remove the two mounting bolts.
(b)  Disconnect the front side claw groove of the cord cover

from the claw of the lower cover, and remove the cord
cover.

7. 

REMOVE RH ENGINE WIRE COVER
Remove the bolt and engine wire cover.

8. 

REMOVE LH ENGINE WIRE COVER
Remove the two bolts and engine wire cover.

9. 

REMOVE VSV FOR EVAP SYSTEM
Remove the two bolts, and disconnect the VSV from cylinder
head and timing belt cover.

10.  REMOVE RH NO.3 TIMING BELT COVER

Remove the three bolts and timing belt cover.

EM–12

–

ENGINE MECHANICAL

Engine Tune–Up

11.  DISCONNECT FUEL INLET HOSE FROM LH DELIVERY

PIPE
Remove the pulsation damper and two gaskets, and discon-
nect the inlet hose.

12. DISCONNECT FUEL RETURN HOSE FROM FUEL

RETURN PIPE

13.  DISCONNECT PCV HOSE FROM LH CYLINDER HEAD

14.  REMOVE LH NO.3 TIMING BELT COVER

(a)  Remove the four mounting bolts.
(b) Disconnect 

the cord grommet from the timing belt cover,

and remove the timing belt cover.

(c)  Remove the cord grommet from the high–tension cord.

15.  DISCONNECT HEATER WATER VALVE FROM BODY

(a)  Disconnect the VSV connector.
(b)  Remove the bolt holding the engine wire clamp to the

water valve bracket.

(c)  Remove the two bolts, and disconnect the water valve

and bracket assembly.

16.  REMOVE THROTTLE BODY

(a)  Disconnect the following connectors:

(1)

Throttle position sensor connector

(2)

(w/ TRAC)
Sub–throttle position sensor connector

(3)

(w/ TRAC)
Sub–throttle actuator connector

(b)  Disconnect the following hoses:

(1)

Water by–pass hose from ISC valve

(2)

(USA Spec.)
Vacuum hose from throttle body

(3)

(Exc. USA Spec.)
Three vacuum hoses from throttle body

–

ENGINE MECHANICAL

Engine Tune–Up

EM–13

(c)  Remove the two bolts and two nuts, disconnect the

throttle 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 the

cylinder head.

(b) Disconnect 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

–

ENGINE MECHANICAL

Engine Tune–Up