1991 LEXUS SC400 check oil

VANE PUMPThe main component parts of the vane pump, such as the cam ring, rotor, vanes and flow control valve
are high precision parts and must be handled carefully. Also, because this pump produces a very high fluid
pressure, O±rings are used for sealing each part. When reassembling t\
he pump, always use new O±rings.
In the flow control valve, there is a relief valve which controls the maximum pressu\
re of the pump. The
amount of this maximum pressure is very important; if it is too low, there will be insufficient power steering
assistance and if too high, it will have an adverse effect on the pressure hoses, oil seals, etc. If the maximum
pressure is either too high or too low due to a faulty relief valve, do \
not disassemble or adjust the relief valve,
but replace the flow control valve as an assembly.
The clearance between the flow control valve and pump body installation hol\
e is very important. After
manufacture, the factory measures the size of the installation hole and outer circumf\
erence of the flow con-
trol valve, and punches a mark accordingly. Therefore, when replacing the flow control valve, be sure to
do so with one having the same mark in order to ensure the proper cleara\
nce.
The functional parts of the pump which produce fluid pressure are the cam r\
ing, rotor and vanes, and these
should be checked for wear. If the clearance between each is not within standard when reassembling\
, any
worn parts should be replaced.
In this case, the replaced cam ring and rotor should be of the same length\
(have the same mark), and the
vanes should be replaced with those having a length corresponding to that mark, other\
wise the proper
thrust clearance cannot be obtained. If there is too much thrust clearance, there will be insufficient fluid
pressure at low speeds. If there is too little thrust clearance, it may \
result in seizure of the vanes.
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STEERING POWER STEERINGSR±105
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GEAR HOUSING
If the gear housing is secured directly in a vise during overhaul, there i\
s danger of deforming it, so always
first secure it in the SST provided (rack & pinion steering rack housing stand) before placing it in the vise.
The oil seals on both sides of the power cylinder are for the prevention of\
leakage of the high pressure fluid
which acts on the piston. Always use new oil seals when reassembling and be v\
ery careful not to scratch
or damage them.
Because of the high pressure, even the slightest scratch will cause fluid leakage, \
resulting in an inoperative
power steering system.
Also, be very careful not to scratch the sliding portion of the rack which ma\
kes contact with the oil seals.
When removing the rack ends from the rack, it is very easy to cause a burr w\
hen holding the tip of the rack
with a wrench. Therefore, before assembling the rack, first check the tip fo\
r burrs and remove any with an
oil stone.
Teflon rings are used for the piston and control valve. These teflon rings are highly durable against wear,
but if it is necessary to replace them, be careful not to stretch the new o\
nes.
After installing a teflon ring into its groove, snug it down into the gr\
oove before assembly of the cylinder
or housing to prevent possible damage.
SR±106
±
STEERING POWER STEERING
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ON±VEHICLE INSPECTION
CHECK IDLE±UP
SR0FZ±04
1. WARM UP ENGINE
2. TURN AIR CONDITIONER SWITCH OFF
3. CHECK IDLE±UP
(a) Fully turn the steering wheel.
(b) Check that the engine rpm decreases when the air controlvalve hose is pinched.
(c) Check that the engine rpm increases when the air control valve hose is released.
FLUID LEVEL CHECK
SR0G0±03
1. KEEP VEHICLE LEVEL
2. BOOST FLUID TEMPERATUREWith the engine idling at 1,000 rpm or less, turn the steering
wheel from lock to lock several times to boost fluid tempera-
ture.
Fluid temperature:
805C (176 5F)
3. STOP ENGINE
4. CHECK FOR FOAMING OR EMULSIFICATION
HINT: Foaming and emulsification indicate either the exis-
tence of air in the system or that the fluid level is too low.
5. CHECK FLUID LEVEL IN OIL RESERVOIR Check the fluid level and add fluid if necessary.
Fluid:
ATF DEXRON
[ II
HINT: Check that the fluid level is within the HOT LEVEL of
the dipstick of the reservoir cap. If the fluid is cold, check that
it is within the COLD LEVEL of the dipstick.
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STEERING POWER STEERINGSR±113
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POWER STEERING SYSTEM BLEEDING
SR0G2±04
1. CHECK FLUID LEVEL IN OIL RESERVOIRCheck the fluid level and add fluid if necessary.
Fluid:
ATF DEXRON
[ II
HINT: Check that the fluid level is within the HOT LEVEL of
the dipstick of the reservoir cap. If the fluid is cold, check that
it is within the COLD LEVEL of the dipstick.
2. START ENGINE AND TURN STEERING WHEEL FROM LOCK TO LOCK 3 OR 4 TIMES
With the engine speed below 1,000 rpm, turn the steering
wheel to left or right full lock and keep it there for 2±3 se-
conds, then turn the wheel to the opposite full lock and keep
it there for 2±3 seconds.
3. CHECK THAT FLUID IN OIL RESERVOIR IS NOT FOAMY OR CLOUDY AND DOES NOT RISE OVER MAXIMUM
WHEN ENGINE IS STOPPED
Measure the fluid level with the engine running. Stop the en-
gine and measure the fluid level.
Maximum rise:
5 mm (0.20 in.)
If a problem is found, repeat fluid replacement on page
SR±114. Rep air the PS if the problem persists.
OIL PRESSURE CHECK
SR0G3±03
1. CONNECT PRESSURE GAUGE
(a) Using SST, disconnect the pressure line joint.SC 400:
SST 09631±22020
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STEERING POWER STEERINGSR±115
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(b) Check the flow control valve for leakage.Close one of the holes and apply compressed air 392 ±490
kPa (4±5 kgf/ cm
2, 57±71 psi) into the opposite side, and con-
firm that air does not come out from the end holes.
If necessary, replace the valve with one having the same let-
ter as inscribed on the front housing.
Inscribed mark:
A, B, C, D, E or F
4. INSPECT FLOW CONTROL SPRINGUsing a calipers, measure the free length of the spring.
Minimum spring length:
36 mm (1.42 in.)
If not within specification, replace the spring.
5. IF NECESSARY, REPLACE OIL SEAL
(a) Using SST, tap out the oil seal. SST 09631±10030
(b) Using a 22 mm socket wrench and hammer, drive in a new oil seal.
NOTICE: Make sure you install the oil seal facing the correct
direction.
(c) Coat the oil seal lip with power steering fluid.
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STEERING POWER STEERINGSR±125
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(b) Using SST, press the rack until the end stopper slightlytouches the press block.
SST 09612±24014 (09612±10061)
(c) Slightly tap the rack end with a brass bar and hammer.
(d) Pull out the rack with cylinder end stopper, 2 spacers and oil seal.
16. REMOVE RACK HOUSING OIL SEAL AND SPACER Using SST, tap out the oil seal and spacer.
SST 09631±12020, 09631±20031
GEAR HOUSING COMPONENTS
INSPECTION AND REPAIR
SR0NZ±01
1. INSPECT RACK
(a) Using a dial indicator, check the rack for runout and for teethwear or damage.
Maximum runout:
0.3 mm (0.012 in.)
(b) Check the back surface for wear or damage.If faulty, replace it.
2. IF NECESSARY, REPLACE RACK HOUSING BEARING AND OIL SEAL
(a) Using SST, remove the bearing. SST 09612±30012
NOTICE: Be careful not to damage the rack housing.
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STEERING POWER STEERINGSR±153
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(e) Using snap ring pliers, install a new snap ring.
5. AIR TIGHTNESS TEST
(a) Install SST to the unions of the rack housing.SST 09631±12071
(b) Apply 53.3 kPa (400 mmHg, 15.75 inVHg) of vacuum for about 30 seconds.
(c) Check that there is no change in the vacuum. If there is change in the vacuum, check the installation of the
rack housing oil seals.
6. INSTALL CONTROL VALVE
(a) Coat the teflon rings with power steering fluid.
(b) Push the control valve into the rack housing.
7. INSTALL CONTROL VALVE HOUSING
(a) Coat a new O±ring with power steering fluid, and install it to the valve housing.
(b) Using a hexagon wrench, tighten the 2 bolts.
Torque: 18 N Vm (185 kgf Vcm, 13 ft Vlbf)
NOTICE: To prevent oil seal lip damage, wind vinyl tape on the
serration part of the control valve shaft.
8. INSTALL LOWER BEARING AND SPACER
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STEERING POWER STEERINGSR±159
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2. REMOVE STEERING WHEEL PAD
(a) Place the front wheels facing straight ahead.
(b) Using a torx wrench, loosen the 4 screws. Torx wrench: T30(Part No. 09042±00010 or locally manufactured tool)
(d) Loosen the torx screws until the groove along the screw circumference catches on the screw case.
(e) P u l l t h e w heel pad out from the steering wheel and
disconnect the SRS connector.
NOTICE: When removing the wheel pad, take care not to
pull the airbag wire harness.
CAUTION:
w When storing the wheel pad, keep the upper surface of
the pad facing upward (See pages RS±3).
w Never disassemble the wheel pad.
3. REMOVE STEERING WHEEL
(a) Disconnect the connector.
(b) Remove the set nut.
(c) Place matchmarks on the steering wheel and main shaft.
(d) Using SST, remove the steering wheel.
SST 09213±31021
4. REMOVE AND INSTALL SPIRAL CABLE FROM/TO COMBINATION SWITCH
(See page BE±51)
NOTICE: Do not disassemble the spiral cable or apply oil
to it.
5. CENTER SPIRAL CABLE
(a) Check that the front wheels are facing straight ahead.
(b) Turn the spiral cable c ounterclockwise by hand until it
becomes harder to turn the cable.
(c) Then rotate the spiral cable clockwise about 3 turns to align the red mark.
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SUPPLEMENTAL RESTRAINT SYSTEM STEERING WHEEL PAD AND SPIRAL CABLERS±19
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