INFINITI QX56 2011 Factory Service Manual

STRUCTURE AND OPERATIONSCS-11
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When system pressure decreases, influent oil is dist ributed to both pipes by gas spring reaction force of
nitrogen gas via PPMU pipe A and PPMU pipe B to control sudden decrease in system pressure.
AccumulatorINFOID:0000000006256004
Influent oil from both front and rear shock absorbers on the outer ring flows simultaneously into the oil cham-
ber during cornering, and gas spring reaction force of ni trogen gas increases pressure, according to the influ-
ent oil level. As for inner ring side, the gas spring conv eys oil from the oil chamber to both front and rear shock
absorbers and decreases pressure, according to the oil level.
PPMU PipeINFOID:0000000006256005
PPMU and right and left tubes are connected. When oil in creases according to increase of system pressure,
increased amount of oil is sent to PPMU. When system pressure decreases, oil discharged from PPMU is sent
to right and left tubes.
1. Oil chamber 2. Bellows 3. Gas chamber
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1. Oil chamber 2. Gas chamber 3. Bellows
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Revision: 2010 May2011 QX56

SCS-12
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SYSTEM
SYSTEM
System DiagramINFOID:0000000006256006
System DescriptionINFOID:0000000006256007
 Drivability during cornering and driving on rough road
is improved by mechanically generating oil pressure
by connecting 4 units of shock absor bers to front, rear, right, and left by piping lines of 2 systems.
 Oil filling and system diagnosis can be performed using PPMU.
OPERATING PRINCIPLE
During cornering (Front and rear wheels in the outer side of corner: compressing)
When shock absorber in the outer side of corner is compressed during cornering, oil moves along piping path
and overflowing oil from piping path flows in accumulato r in the outer side of corner. Then, pressure increases
by action of gas spring of nitrogen gas acco rding to amount of oil that flows in.
Pressure in the inner side of corner decreases, since oil is discharged from accumulator by stroke (extending
direction) of shock absorber.
The pressure difference generates stabilizer-like action to maintain balance in vehicle posture for a steady
driving at cornering.
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Revision: 2010 May2011 QX56

SYSTEMSCS-13
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During rough road driving (Front wheel LH: compressing, front wheel RH: extending, rear wheel LH: extending, rear
wheel RH: compressing)
Discharged oil from each shock absorber moves along piping
path, but oil does not overflow from piping path,
since oil moves in between each shock absorber. Oil does not flow in accumulator and system pressure does
not increase.
Since the oil from the contracted shock absorber flow s into the shock absorber upper chamber, stabilizer-like
action is not generated. This improves the adhes ion level and the running performance on rough roads.
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Revision: 2010 May2011 QX56

SCS-14
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SYSTEM
Component Description
INFOID:0000000006256008
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Component parts Description
Needle valve A Needle valve for oil filling or trouble diagnosis. It is usually closed.
Needle valve B Needle valve for trouble diagnosis. It is usually open.
Needle valve C Needle valve for oil filling or trouble diagnosis. It is usually closed.
Needle valve D Needle valve for trouble diagnosis. It is usually open.
Needle valve E Needle valve for oil filling or trouble diagnosis. It is usually closed.
Relief valve If system pressure increases, then the orifice becomes clogged and oil flow into PPMU be-
comes disrupted, resulting in a large pressure difference between PPMU and both pipes. In
this case, the relief valve opens to let the oil flow.
Oil injection jack  Oil filling inlet
 For basic inspection use.
Air bleeder For air bleeding use.
Revision: 2010 May2011 QX56

CHECK SYSTEM PRESSURESCS-15
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BASIC INSPECTION
CHECK SYSTEM PRESSURE
Work ProcedureINFOID:0000000006256009
CAUTION:
 Clean surrounding areas of oil inj ection jack using steam before starting operation, since there may
be mud on it.
 Clean oil pressure gauge (special service tool: KV40108000) jack with steam before use.
1. Lift up the vehicle.
2. Remove protector of PPMU.
3. Remove cap of oil injection jack.
4. Install an oil pressure gauge (SST: KV40108000) (A) to oil injec- tion jack.
CAUTION:
 Jack must be securely inserted until a click sound can be
heard.
 Pressure reducing valve (B) of the oil pressure gauge
must be closed.
5. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations.
CAUTION:
Never loosen the needle valve more than required.
6. Refer to the figure and check the specified pressure.
7. Tighten needle valves A, C, and E of PPMU to the specified torque.
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Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
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SCS-16
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CHECK SYSTEM PRESSURE
8. Loosen pressure reducing valve (A) of oil pressure gauge and
then lower pressure.
CAUTION:
Be careful since oil drains swiftly from oil drain hole (B).
9. Check that reading of oil pressure gauge is 0 MPa.
10. Remove oil pressure gauge.
11. Install cap of oil injection jack.
12. Install protector of PPMU. Refer to SCS-39, "
PPMU, MIDDLE
TUBE ASSEMBLY, PPMU PIPE : Exploded View".
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Revision: 2010 May2011 QX56

PRESSURE REDUCING METHODSCS-17
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PRESSURE REDUCING METHOD
Work ProcedureINFOID:0000000006256010
CAUTION:
 Clean surrounding areas of oil inj ection jack using steam before starting operation, since there may
be mud on it.
 Clean oil pressure gauge (special service tool: KV40108000) jack with steam before use.
1. Lift up the vehicle.
2. Remove protector of PPMU.
3. Remove cap of oil injection jack.
4. Install an oil pressure gauge (SST: KV40108000) (A) to oil injec- tion jack.
CAUTION:
 Jack must be securely inserted until a click sound can beheard.
 Pressure reducing valve (B) of the oil pressure gauge
must be closed.
5. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations.
CAUTION:
Never loosen the needle valve more than required.
6. Loosen pressure reducing valve (A) of oil pressure gauge and then lower pressure.
CAUTION:
Be careful since oil drains sw iftly from oil drain hole (B).
7. Check that reading of oil pressure gauge is 0 MPa.
8. Tighten needle valves A, C, and E of PPMU to the specified torque.
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Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
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Revision: 2010 May2011 QX56

SCS-18
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AIR BLEEDING METHOD
AIR BLEEDING METHOD
Work ProcedureINFOID:0000000006256011
WARNING:
 Always check the piping for loose co
nnections, damage, or twists before starting operation, since
pressure in hydraulic circuit b ecomes high during operation.
 When repairing or replacing a malfunctioning pa rt, always release pressure from hydraulic circuit,
since dangerous conditions may be created when oil leakage occurs during air bleeding operation.
CAUTION:
 Clean surrounding areas of oil injection jack and air bleeder using steam before starting operation,
since there may be mud on it.
 Clean suspension oil pump (special servi ce tool: KV40107700) jack with steam before use.
 Check system pressure again 1 day or more after bleeding operation is complete, since system pres-
sure may decrease when air bleeding is insufficient.
1. Lift up the vehicle.
2. Remove protector of PPMU.
3. Remove cap of oil injection jack.
4. Install hose (A) of a suspension oil pump (SST: KV40107700) to oil injection jack.
CAUTION:
Jack must be securely inserted until a click sound can be
heard.
5. Loosen pressure reducing valve (A) of hose portion of suspen- sion oil pump.
6. Set knob (A) of suspension oil pump to the direction as shown in the figure.
7. Close pressure reducing valve of hose portion of suspension oil pump while sending oil by applying pressure using suspension
oil pump. (Air bleeding in hose is complete.)
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Revision: 2010 May2011 QX56

AIR BLEEDING METHODSCS-19
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8. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations.
CAUTION:
Never loosen the needle valve more than required.
9. Install bleeder tube and drain tank to bleeder valve in upper side of rear shock absorber RH.
10. Loosen bleeder valve and bleed air while sending oil by applying pressure using suspension oil pump, and then quickly tighten air
bleeder.
CAUTION:
Be careful that oil in suspensi on oil pump is not at half or
less.
11. Repeat step 10 until no air appears in bleeder tube.
12. Tighten bleeder valve to the specified torque. Refer to SCS-32, "
FRONT TUBE ASSEMBLY : Exploded
View" (front shock absorber), SCS-39, "PPMU, MIDDLE TUBE ASSEMB LY, PPMU PIPE : Exploded
View" (upper side of rear shock absorber).
13. Perform operation according to steps 9 to 12 in the order of rear shock absorber RH (lower side) → front
shock absorber RH (upper side and lower side) → rear shock absorber LH (upper side and lower side) →
front shock absorber LH (upper side and lower side).
14. Repeat steps 9 to 13 (2nd turn).
15. Refer to the figure and send oil by applying pressure.
16. Tighten needle valves A, C, and E of PPMU to the specified torque.
17. Set knob (A) of suspension oil pump to the direction as shown in the figure and check that reading of pressure gauge is 0 MPa.
18. Remove hose of suspension oil pump.
19. Install cap of oil injection jack.
20. Install protector of PPMU. Refer to SCS-39, "
PPMU, MIDDLE
TUBE ASSEMBLY, PPMU PIPE : Exploded View".
Lower side of rear shock absorber
Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
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Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
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Revision: 2010 May2011 QX56

SCS-20
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CHECK INTERNAL LEAKAGE
CHECK INTERNAL LEAKAGE
Work ProcedureINFOID:0000000006256012
CAUTION:
 Clean surrounding areas of
oil injection jack using steam before starting operation, since there may
be mud on it.
 Clean oil pressure gauge (special service tool: KV40108000) jack with steam before use.
1. Remove protector of PPMU.
2. Remove cap of oil injection jack.
3. Install an oil pressure gauge (SST: KV40108000) (A) to oil injec- tion jack.
CAUTION:
 Jack must be securely inserted until a click sound can beheard.
 Pressure reducing valve (B) of the oil pressure gauge
must be closed.
4. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations. CAUTION:
Never loosen the needle valve more than required.
5. Lift up the vehicle. CAUTION:
Check that tires never contact the ground.
6. Tighten needle valves C and E of PPMU.
7. Loosen lock nut of needle valve D of PPMU and then tighten needle valve D.
8. Lift down the vehicle. CAUTION:
Check that the lift is fully lowered.
9. Write down a value of the oil pressure gauge after 5 minutes.
10. Tighten needle valve A of PPMU.
11. Loosen lock nut of needle valve B of PPMU and then tighten needle valve B.
12. Loosen needle valve C of PPMU by approximately 2 rotations. CAUTION:
Never loosen the needle valve more than required.
13. Read a value of oil pressure gauge.
14. Compare difference of reading with pressure reading in step 9.
15. Tighten needle valves A, C, and E of PPMU to the specified torque.
16. Loosen needle valves B and D of PPMU by approximatel y 2 rotations and then tighten lock nut to the
specified torque.
CAUTION:
Never loosen the needle valve more than required.
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Pressure difference
0.1 MPa or more : Normal
0.1 MPa or less : Malfunction
: 8.3 N·m (0.85 kg-m, 73 in-lb)
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Revision: 2010 May2011 QX56