1991 LEXUS SC400 engine

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Page 1776 of 4087

LEXUS SC400 1991  Service Repair Manual 
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
twe

Page 1777 of 4087

LEXUS SC400 1991  Service Repair Manual 
(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)  Re

Page 1778 of 4087

LEXUS SC400 1991  Service Repair Manual 
HINT: Arrange the valve lifters and adjusting shims in correct
order.
2. REMOVE VALVES (a)  Using SST, compress the valve spring and remove thetwo keepers.
SST 09202±70010
(b)  Remove the following

Page 1779 of 4087

LEXUS SC400 1991  Service Repair Manual 
INSPECTION, CLEANING AND REPAIR
OF CYLINDER HEAD COMPONENTS
1.  CLEAN TOP SURFACES OF PISTONS AND CYLINDERBLOCK
(a)  Turn the crankshaft and bring each piston to top deadcenter (TDC). Using a gasket

Page 1780 of 4087

LEXUS SC400 1991  Service Repair Manual 
D. Clean cylinder headsUsing a soft brush and solvent, thoroughly clean the cylinder
heads.
3.  INSPECT CYLINDER HEADS
A. Inspect for flatness Using a precision straight edge and feeler gauge, measur

Page 1781 of 4087

LEXUS SC400 1991  Service Repair Manual 
5.  INSPECT VALVE STEMS AND GUIDE BUSHINGS(a)  Using a caliper gauge, measure the inside diameter ofthe guide bushing.
Bushing  inside diameter:
6.010±6.030 mm (0.2366±0.2374 in.)
(b)  Using a micr

Page 1782 of 4087

LEXUS SC400 1991  Service Repair Manual 
(b)  Gradually heat the cylinder head to 80±1005C (176±2125F).
(c)  Using SST and a hammer, tap out the guide bushing.
SST 09201±70010
(d)  Using a caliper g auge, measure the bushing bore
diamete

Page 1783 of 4087

LEXUS SC400 1991  Service Repair Manual 
(g)  Using SST and a hammer, tap in a new guide bushinguntil the  snap ring makes contact with the cylinder head.
SST 09201±70010
HINT: Different the bushings are used for the intake and ex-
haust.