Lexus SC300 / Lexus SC400. Manual - part 573

INSTALLATION OF CYLINDER HEADS

(See Components on pages 

EM–58

 and 59)

1.  INSTALL RH EXHAUST MANIFOLD TO RH CYLINDER

HEAD
(a)  Place a new gasket on the cylinder head with the white

painted marks facing the manifold side.

NOTICE: Be careful of the installation direction.

(b)  Install the exhaust manifold with the eight new nuts.

Uniformly tighten the nuts in several passes.

Torque: 39 N

⋅

m (400 kgf

⋅

cm, 29 ft

⋅

lbf)

(c)  Install the main oxygen sensor.

Torque: 44 N

⋅

m (450 kgf

⋅

cm, 33 ft

⋅

lbf)

(d)  Install the heat insulator with the three bolts.

2.  INSTALL LH EXHAUST MANIFOLD TO LH CYLINDER

HEAD
(a)  Place a new gasket on the cylinder head with the white

painted marks facing the manifold side.

NOTICE: Be careful of the installation direction.

–

ENGINE MECHANICAL

Cylinder Heads

EM–91

(b)  Install the exhaust manifold with the eight new nuts.

Uniformly tighten the nuts in several passes.

Torque: 39 N

⋅

m (400 kgf

⋅

cm, 29 ft

⋅

lbf)

(c)  Install the main oxygen sensor.

Torque: 44 N

⋅

m (450 kgf

⋅

cm, 33 ft

⋅

lbf)

(d)  Install the heat insulator with the three bolts.

3. 

INSTALL CYLINDER HEADS

A.

Place cylinder heads on cylinder block
(a)  Place two new cylinder head gaskets in position on the

cylinder block.

HINT: On the rear side of the cylinder head gasket are
painted marks to distinguish the LH and RH banks, a white
painted mark for the RH bank and a yellow painted mark for
the LH bank.
NOTICE: Be careful of the installation direction.
(b)  Place the two cylinder heads in position on the cylinder

head gaskets.

EM–92

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ENGINE MECHANICAL

Cylinder Heads

B.

Install cylinder head bolts
HINT:

•

The cylinder head bolts are tighten in two progressive
steps (steps (c) and (e)).

•

If any one of the cylinder head bolts broken or deformed,
replace it.

(a) Apply 

a 

light coat of engine oil on the threads and under

the heads of the cylinder head bolts.

(b)  Temporarily install the twenty plate washers and

cylinder head bolts.

(c) Uniformly 

tighten the ten cylinder head bolts on one side

of the cylinder head in several passes in the sequence
shown, then do the other side as shown.

Torque: 39 N

⋅

m (400 kgf

⋅

cm, 29 ft

⋅

lbf)

If any one of the bolts does not meet the torque specification,
replace the bolt.

(d)  Mark the front of the cylinder head bolt head with paint.

(e)  Retighten the cylinder head bolts 90

°

 in the numerical

order shown.

(f)  Check that the painted mark is now at a 90

°

 angle to

front.

4. 

CONNECT MAIN OXYGEN SENSOR CONNECTORS
Connect the RH and LH oxygen sensor connector.

5. 

INSTALL CIRCULAR PLUGS
(a)  Place two new circular plugs in position on the cylinder

heads, facing the cup side forward.

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ENGINE MECHANICAL

Cylinder Heads

EM–93

(b)  Remove any old packing (FIPG) material.
(c)  Apply seal packing to the bearing caps as shown.

Seal packing: Part No. 08826–00080 or equivalent

(d)  (RH Cylinder Head)

Install the bearing cap (mark ”I1”) in position with the ar-
row mark facing rearward.

(e)  (LH Cylinder Head)

Install the bearing cap (mark ”I6”) in position with the ar-
row mark facing forward.

(f)  Install a new seal washer to the bearing cap bolt.
(g)  Apply a light of engine oil on the threads of the bearing

cap bolt.

(h)  Install the four bearing cap bolts.

Torque: 16 N

⋅

m (160 kgf

⋅

cm, 12 ft

⋅

lbf)

HINT: Use silver colored bolts 38 mm (1.50 in.) in length.

6. 

ASSEMBLE EXHAUST CAMSHAFTS
(a)  Install the following parts:

(1)

Camshaft gear spring

(2)

Camshaft sub–gear

(3)

Wave washer

(b)  Using snap ring pliers, install the snap ring.

(c) Mount the hexagon wrench head portion  of the

camshaft in a vice.

EM–94

–

ENGINE MECHANICAL

Cylinder Heads