LEXUS SC400 1991 Service Repair Manual

30. REMOVE OIL DIPSTICK AND GUIDE FORTRANSMISSION
(a) Remove the bolt holding the oil dipstick to the LH cylinder head.
(b) Pull out the dipstick guide together with the dipstick from the oil pan.
(c) Remove the O±ring from the dipstick guide.
31. REMOVE OIL DIPSTICK AND GUIDE FOR ENGINE
32. REMOVE EGR PIPE
(a) Remove the 2 bolts holding the EGR pipe to the RH exhaust pipe.
(b) Remove the EGR pipe and gasket.
33. DISCONNECT ENGINE WIRE FROM CYLINDER HEADS
(a) Remove the 2 bolts, and disconnect the engine wire protector
from the RH cylinder head.
(b) Remove the bolt, and disconnect the ground strap from the RH cylinder head.
(c) Remove the 5 bolts, and disconnect the engine wire protector
from the LH cylinder head.
34. REMOVE ENGINE HANGERS Remove the 2 bolts and engine hanger. Remove the 2 engine
hangers.
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35. REMOVE CYLINDER HEAD COVERSRemove the 8 bolts, seal washers, cylinder head cover and
gasket. Remove the 2 cylinder head covers.
36. IF NECESSARY, REMOVE SEMI±CIRCULAR PLUGS
37. REMOVE CAMSHAFTS
NOTICE: Since the thrust clearance of the camshaft is small,
the camshaft must be kept level while it is being removed. If the
camshaft is not kept camshaft is not kept level, the portion of
the cylinder head receiving 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. Remove exhaust camshaft from RH cylinder head
(a) Boring the service bolt hole of the driven sub±gear upward by turning the hexagon wrench head portion of the exhaust
camshaft with a wrench.
(b) Secure the exhaust camshaft sub±gear to the drive gear with
a service bolt.
Recommended service bolt: 6 mm for thread diameter
1.0 mm for thread pitch
16 ± 20 mm (0.63 ± 0.79 in.) for bolt length
HINT: When removing the camshaft, make sure that the tor-
sional spring force of the sub±gear has been eliminated by
the above operation.
(c) Set the timing mark (1 dot mark) of the camshaft driven gear at approx. 10
angle by turning the hexagon wrench head
portion of the exhaust camshaft with a wrench.
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(d) Alternately loosen and remove the 2 bearing cap boltsholding the intake camshaft side of the oil feed pipe to the
cylinder head.
(e) Uniformly loosen and remove the 8 bearing cap bolts in several passes, in the sequence shown.
(f) Remove the oil feed pipe, 4 bearing caps and ex haust
camshaft.
B. Remove intake camshaft from RH cylinder head
(a) Remove the rear bearing cap.
(b) Set the timing mark (1 dot mark) of the camshaft drive gear at approx. 45
angle by turning the hexagon wrench head
portion of the intake camshaft with a wrench.
(c) Uniformly loosen and remove the 8 bearing cap bolts in several passes, in the sequence shown.
(d) Remove the 4 bearing caps, oil seal and intake camshaft.
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C. Remove exhaust camshaft from LH cylinder head
(a) Boring the service bolt hole of the driven sub±gear upwardby turning the hexagon wrench head portion of the exhaust
camshaft with a wrench.
(b) Secure the exhaust camshaft sub±gear to drive gear with a service bolt.
Recommended service bolt:6 mm for thread diameter
1.0 mm for thread pitch
16 ± 20 mm (0.63 ± 0.79 in.) for bolt length
HINT: When removing the camshaft, make sure that the tor-
sional spring force of the sub±gear has been eliminated by
the above operation.
(c) Set the timing mark (2 dot marks) of the camshaft drive gear at approx. 15
angle by turning the hexagon wrench head
portion of the exhaust camshaft with a wrench.
(d) Alternately loosen and remove the 2 bearing cap bolts holding the intake camshaft side of the oil feed pipe to the
cylinder head.
(e) Uniformly loosen and remove the 8 bearing cap bolts in several passes, in the sequence shown.
(f) Remove the oil feed pipe, 4 bearing caps and ex haust
camshaft.
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D. Remove intake camshaft from LH cylinder head
(a) Remove the bearing cap second from the front.
(b) Set the timing mark (1 dot mark) of the camshaft drive gearat approx. 60
angle by turning the hexagon wrench head
portion of the intake camshaft with a wrench.
(c) Uniformly loosen and remove the 8 bearing cap bolts in several passes, in the sequence shown.
(d) Remove the 4 bearing caps, oil seal and intake camshaft.
HINT: Arrange the bearing caps in correct order.
38. DISASSEMBLE EXHAUST CAMSHAFTS
(a) Mount the hexagon wrench head portion of the camshaft in a vise.
NOTICE: Be careful not to damage the camshaft.
(b) Insert service bolt A into the service hole of the camshaft sub±gear.
(c) Using a screwdriver, turn the sub±gear clockwise, and
remove service bolt B.
NOTICE: Be careful not to damage the camshaft.
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(d) Using snap ring pliers, remove the snap ring.
(e) Remove the following parts:(1) Wave washer
(2) Camshaft sub±gear
(3) Camshaft gear spring
HINT: Arrange the camshaft sub±gears and gear spring (RH
and LH sides).
39. REMOVE CIRCULAR PLUGS Remove the 2 bolts, seal washers, bearing cap and circular
plug. Remove the 2 circular plugs.
HINT: Arrange the bearing caps (RH and LH sides).
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40. DISCONNECT MAIN HEATED OXYGEN SENSORCONNECTORS
Disconnect the RH and LH oxygen sensor connectors.
41. REMOVE CYLINDER HEADS
(a) Uniformly loosen the ten cylinder head bolts one side of each
cylinder head in several passes, in the sequence shown,
then do the other side as shown. Remove the 20 cylinder
head bolts and plate washers.
NOTICE:
w Cylinder head warpage or cracking could result from
removing bolts in incorrect order.
w 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
cylinder block into the oil pan.
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(b) Lift the cylinder head from the dowels on the cylinder block,and place the 2 cylinder heads on wooden blocks on a bench.
HINT: If the cylinder head is 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.
42. REMOVE EXHAUST MANIFOLD FROM RH CYLINDERHEAD
(a) Remove the 3 bolts and heat insulator.
(b) Remove the main heated oxygen sensor.
(c) Remove the 8 nuts, exhaust manifold and gasket.
43. REMOVE EXHAUST MANIFOLD FROM LH CYLINDER
HEAD
(a) Remove the 3 bolts and heat insulator.
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(b) Remove the main heated oxygen sensor.
(c) Remove the 8 nuts, exhaust manifold and gasket.
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CYLINDER HEAD DISASSEMBLY
(See Components for Removal and Installation)
1. REMOVE VALVE LIFTERS AND SHIMSHINT: Arrange the valve lifters and shims in correct order.
2. REMOVE VALVES
(a) Using SST, compress the valve spring and remove the 2 keepers.
SST 09202±70010
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(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 incorrect order.
(c) Using needle±nose pliers, remove the oil seal.
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