Lexus SC300 / Lexus SC400. Service manual — part 372

B. Install cylinder head bolts

HINT:

•

The cylinder head bolts are tightened in 2 progressive
steps (steps (c) and (e)).

•

If any cylinder head bolt is 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) Install the plate washer to the cylinder head bolt.
(c) Install and uniformly tighten the 10 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 cylinder head bolts does not meet the torque
specification, replace the cylinder head bolt.

NOTICE: Do not drop the plate washer for cylinder head bolt

into portion A of the cylinder head. If dropped into portion A,

the plate washer will pass through the cylinder head and cylin-

der block into the oil pan.

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

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EG–111

(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 HEATED OXYGEN SENSOR

CONNECTORS
Connect the RH and LH oxygen sensor connectors.

5.

INSTALL CIRCULAR PLUGS

(a) Place 2 new circular plugs in position on the cylinder heads,

facing the cup side forward.

(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

EG–112

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ENGINE MECHANICAL

(d) RH Cylinder Head:

Install the bearing cap (mark “11”) in position with the arrow
mark facing rearward.

(e) LH Cylinder Head:

Install the bearing cap (mark “16”) in position with the arrow
mark facing forward.

(f)

Install a new seal washer to the bearing cap bolt.

(g) Apply a light coat of engine oil on the threads of the bearing

cap bolt.

(h) Install the 4 bearing cap bolts. Alternately tighten 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 CAMSHAFT

(a) Install the following parts:

(1) Camshaft gear spring
(2) Camshaft

sub–gear

(3) Wave

washer

HINT: Align the pins on the gears with the spring ends.

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

(c) Mount the hexagon wrench head portion of the camshaft in

a vise.
NOTICE: Be careful not to damage the camshaft.

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(d) Insert service bolt A into the service hole of the camshaft

sub–gear.

(e) Using a screwdriver, align the holes of the camshaft drive

gear and sub–gear by turning camshaft subgear clockwise,
and temporarily install service bolt B.
NOTICE: Be careful not to damage the camshaft.

(f) Align the gear teeth of the drive gear and sub–gear, and

tighten service bolt B.

7. INSTALL

CAMSHAFTS

NOTICE: Since the thrust clearance of the camshaft is small,

the camshaft must be kept level while it is being installed. If the

camshaft is not kept level, the portion of the cylinder head re-

ceiving the shaft thrust may crack or be damaged, causing the

camshaft to seize or break. To avoid this, the following steps

should be carried out.

A. Install intake camshaft to RH cylinder head
(a) Apply MP grease to the thrust portion of the intake camshaft.
(b) Place the intake camshaft at 45

angle of the timing mark (1

dot mark) on the cylinder head.

(c) Remove any old packing (FIPG) material.
(d) Apply seal packing to the bearing cap (mark “16”) as shown.

Seal packing:

Part No. 08826–00080 or equivalent

(e) Install the front bearing cap (mark “16”) with the arrow mark

facing rearward.
HINT:

•

Installing the front bearing cap will determine the thrust
portion of the camshaft.

•

Align the allow marks at the front and rear of the cylinder
head with the mark on the bearing cap.

EG–114

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