Lexus SC300 / Lexus SC400. Service manual — part 569

45. REMOVE CYLINDER HEADS

(a) Uniformly loosen the ten cylinder head bolts on one side

of each cylinder head in several passes in the sequence
shown, then do the other side as shown. Remove the
twenty cylinder head bolts and plate washers.

NOTICE: Head warpage or cracking could result from re-
moving bolts in an incorrect order.

(b) Lift the cylinder heads from the dowels on the cylinder

block, and place the two cylinder heads on wooden
blocks on a bench.

HINT: If the cylinder head is difficult to lift off, pry between the
cylinder head and cylinder block with a screwdriver.
NOTICE: Be careful not to damage the contact surfaces
of the cylinder head and cylinder block.

46. REMOVE EXHAUST MANIFOLD FROM RH CYLINDER

HEAD
(a) Remove the three bolts and heat insulator.

(b) Remove the main oxygen sensor.

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ENGINE MECHANICAL

Cylinder Heads

EM–75

(c) Remove the eight nuts, exhaust manifold and gasket.

47. REMOVE EXHAUST MANIFOLD FROM LH CYLINDER

HEAD
(a) Remove the three bolts and heat insulator.

(b) Remove the main oxygen sensor.

(c) Remove the eight nuts, exhaust manifold and gasket.

DISASSEMBLY OF CYLINDER HEADS

(See Components on page

EM–59

)

1.

REMOVE VALVE LIFTERS AND ADJUSTING SHIMS

EM–76

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ENGINE MECHANICAL

Cylinder Heads

HINT: Arrange the valve lifters and adjusting shims in correct
order.

2. REMOVE

VALVES

(a) Using SST, compress the valve spring and remove the

two keepers.

SST 09202–70010

(b) Remove the following parts:

(1)

Spring retainer

(2)

Valve spring

(3)

Valve

(4)

Spring seat

HINT: Arrange the valves, valve springs, spring seats and
spring retainers in correct order.

(c) Using needle–nose pliers, remove the oil seal.

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ENGINE MECHANICAL

Cylinder Heads

EM–77

INSPECTION, CLEANING AND REPAIR
OF CYLINDER HEAD COMPONENTS

1. CLEAN TOP SURFACES OF PISTONS AND CYLINDER

BLOCK
(a) Turn the crankshaft and bring each piston to top dead

center (TDC). Using a gasket scraper, remove all the
carbon from the piston top surfaces.

(b) Using a gasket scraper, remove all the gasket material

from the top surfaces of the cylinder block.

(c) Using compressed air, blow carbon and oil from the bolt

holes.

CAUTION: Protect your eyes when using high–pressure
compressed air.

2.

CLEAN CYLINDER HEADS

A.

Remove gasket material Using a gasket scraper, remove
all the gasket material from the cylinder block surface.
NOTICE: Be careful not to scratch the cylinder block con-
tact surface.

B.

Clean combustion chambers
Using a wire brush, remove all the carbon from the combus-
tion chambers.
NOTICE: Be careful not to scratch the cylinder block con-
tact surface.

C.

Clean valve guide bushings
Using a valve guide bushing brush and solvent, clean all the
guide bushings.

EM–78

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ENGINE MECHANICAL

Cylinder Heads