Lexus LS400 (2000 year). Service manual — part 85

EM09H–02

A02105

Compression
Gauge

–

ENGINE MECHANICAL

COMPRESSION

EM–3

1185

COMPRESSION

INSPECTION

HINT:
If there is lack of power, excessive oil consumption or poor fuel
economy, measure the compression pressure.
1.

WARM UP AND STOP ENGINE

Allow the engine to warm up to normal operating temperature.
2.

REMOVE SPARK PLUGS (See page

IG–1

)

3.

CHECK CYLINDER COMPRESSION PRESSURE

(a)

Insert a compression gauge into the spark plug hole.

(b)

Fully open the throttle.

(c)

While cranking the engine, measure the compression
pressure.

HINT:
Always use a fully charged battery to obtain engine speed of
250 rpm or more.
(d)

Repeat steps (a) through (c) for each cylinder.

NOTICE:
This measurement must be done in as short a time as pos-
sible.

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

(e)

If the cylinder compression in one or more cylinders is low,
pour a small amount of engine oil into the cylinder through
the spark plug hole and repeat steps (a) through (c) for
cylinders with low compression.

If adding oil helps the compression, chances are
that the piston rings and/or cylinder bore are worn
or damage.

If pressure stays low, a valve may be sticking or
seating is improper, or there may be leakage past
the gasket.

4.

REINSTALL SPARK PLUGS (See page

IG–1

)

EM09Q–02

P21961

A02246

A02844

EM–34

–

ENGINE MECHANICAL

CYLINDER HEAD

1216

REMOVAL

1.

DISCONNECT TIMING BELT FROM CAMSHAFT TIM-
ING PULLEYS (See page

EM–15

)

2.

REMOVE CAMSHAFT TIMING PULLEYS
(See page

EM–15

)

3.

REMOVE CAMSHAFT POSITION SENSOR
(See page

IG–10

)

4.

DISCONNECT PS PUMP FROM ENGINE
(See page

EM–77

)

5.

DISCONNECT FRONT EXHAUST PIPE FROM TWC

(a)

Remove the 4 bolts and 4 nuts holding the front exhaust
pipe to the TWC.

(b)

Disconnect the front exhaust pipe from the 2 TWC, and
remove the 2 gaskets.

(c)

Remove the 2 bolts and pipe support bracket.

6.

REMOVE TWC

Remove the 3 nuts, TWC and gasket. Remove the 2 TWC.
7.

REMOVE IGNITION COILS (See page

IG–7

)

8.

REMOVE TIMING BELT REAR PLATES

(a)

Remove the 3 bolts, stud bolt, and RH No.1 and No.2 tim-
ing belt rear plates.

(b)

Disconnect the wire clamp from the LH timing belt rear
plate.

(c)

Remove the 3 bolts, LH No.1 and No.2 timing belt rear
plates.

NOTICE:

Be careful not to drop anything inside the timing belt
cover.

Do not allow the belt to come into correct with oil, wa-
ter or dust.

9.

DISCONNECT FUEL INLET HOSE (See page

SF–23

)

10.

REMOVE INTAKE MANIFOLD ASSEMBLY

(a)

Disconnect the accelerator cable.

(b)

Disconnect the throttle position sensor connector.

A02846

(i)

(j)

(l)

(k)

(n)

(m)

A02847

(p)

(o)

A02866

–

ENGINE MECHANICAL

CYLINDER HEAD

EM–35

1217

(c)

Disconnect the accelerator pedal position sensor con-
nector.

(d)

Disconnect the throttle motor connector.

(e)

Disconnect the VSV connector for EVAP.

(f)

Disconnect the VSV connector for ACIS.

(g)

Disconnect the 8 injector connectors.

(h)

Disconnect the noise filter connector.

(i)

Disconnect the brake booster vacuum hose from the
union on the intake manifold.

(j)

Disconnect the PCV hose from the PCV valve on the LH
cylinder head.

(k)

Disconnect the EVAP hose (from the charcoal canister)
from the VSV for EVAP.

(l)

Disconnect the EVAP hose (from the charcoal canister)
from the EVAP pipe on the intake manifold.

(m)

Disconnect the EVAP hose (from the intake air connector)
from the EVAP pipe on the intake manifold.

(n)

Disconnect the PS air hose from the intake manifold.

(o)

Disconnect the No.1 water bypass hose (from the water
inlet housing) from the throttle body.

(p)

Disconnect the No.7 water bypass hose (from the front
water bypass joint) from the throttle body.

(q)

Disconnect the 2 wire clamp from the throttle body.

(r)

Remove the 2 bolts and EVAP pipe from the intake man-
ifold.

(s)

Remove the 2 nuts and accelerator cable bracket.

(t)

Disconnect the VSV connector for ACIS from the No.1 V–
bank cover bracket.

(u)

Remove the 4 bolts and 3 V–bank cover brackets.

(v)

Remove the bolt and VSV for EVAP.

B01208

A02845

B01210

A04269

A02849

EM–36

–

ENGINE MECHANICAL

CYLINDER HEAD

1218

(w)

Disconnect the engine wire from the RH delivery pipe,
rear water bypass joint, intake manifold and cylinder
head.
(1)

Disconnect the 2 wire clamps from the wire clamp
bracket on the RH delivery pipe.

(2)

Remove the 3 bolts, and disconnect the engine wire
protector from the rear water bypass joint and RH
cylinder head.

(3)

Remove the 3 bolts, and disconnect the engine wire
protector and wire clamp bracket from the intake
manifold.

(x)

Remove the 6 bolts, 4 nuts, intake manifold assembly and
2 gaskets.

11.

REMOVE WATER INLET AND INLET HOUSING AS-
SEMBLY (See page

CO–8

)

12.

REMOVE FRONT WATER BYPASS JOINT

(a)

Disconnect the ECT sensor connector.

(b)

Remove the 4 nuts, water bypass joint and 2 gaskets.