Infiniti QX56 (Z62). Manual — part 670
EM-120
< UNIT DISASSEMBLY AND ASSEMBLY >
CYLINDER BLOCK
Measure the outer diameter of piston skirt with a micrometer (A).
Piston-to-Cylinder Bore Clearance
Calculate by piston skirt diameter and cylinder bore inner diameter
[direction (B), position (D)].
(Clearance) = (Cylinder bore inner diameter) – (Piston skirt diameter).
• If the calculated value exceeds the limit, replace piston and piston pin assembly. Refer to
Re-boring Cylinder Bore
1.
Cylinder bore size is determined by adding piston to cylinder bore clearance to piston skirt diameter.
2.
Install main bearing cap, and tighten to the specified torque. Otherwise, cylinder bores may be distorted in
final assembly.
3.
Cut cylinder bores.
NOTE:
• When any cylinder needs boring, all other cylinders must also be bored.
• Do not cut too much out of cylinder bore at a time. Cut only 0.05 mm (0.0020 in) or so in diameter at a
time.
4.
Hone cylinders to obtain the specified piston to cylinder bore clearance.
5.
Measure finished cylinder bore for the out-of-round and taper.
NOTE:
Perform measurement after cylinder bore cools down.
CRANKSHAFT MAIN JOURNAL DIAMETER
• Measure the outer diameter of crankshaft main journals with a micrometer.
Measure point
: Refer to
.
Standard
JPBIA0227ZZ
A
: Longitudinal direction
C
: Top position
E
: Bottom position
f
: 10 mm (0.39 in)
g
: 60 mm (2.36 in)
h
: 120 mm (4.72 in)
JPBIA2279ZZ
Standard and limit
: Refer to
.
Re-bored size calculation: D = A + B – C
where,
D: Bored diameter
A: Piston skirt diameter as measured
B: Piston to cylinder bore clearance (standard value)
C: Honing allowance 0.02 mm (0.0008 in)
Standard
: Refer to
CYLINDER BLOCK
EM-121
< UNIT DISASSEMBLY AND ASSEMBLY >
C
D
E
F
G
H
I
J
K
L
M
A
EM
N
P
O
• If out of the standard, measure the main bearing oil clearance. Then use undersize bearing. Refer to
CRANKSHAFT PIN JOURNAL DIAMETER
• Measure the outer diameter of crankshaft pin journal with a
micrometer (A).
• If out of the standard, measure the connecting rod bearing oil
clearance. Then use undersize bearing. Refer to
.
CRANKSHAFT OUT-OF-ROUND AND TAPER
• Measure the dimensions at four different points as shown in the
figure on each main journal and pin journal with a micrometer.
• Out-of-round is indicated by the difference in the dimensions
between (d) and (c) at (a) and (b).
• Taper is indicated by the difference in the dimensions between.
• If the measured value exceeds the limit, correct or replace crankshaft.
• If corrected, measure the bearing oil clearance of the corrected main journal and/or pin journal. Then select
the main bearing and/or connecting rod bearing. Refer to
.
CRANKSHAFT RUNOUT
• Place V-block on precise flat table, and support the journals on
both ends of crankshaft.
• Place a dial indicator straight up on the No. 3 journal.
• While rotating crankshaft, read the movement of the pointer on a
dial indicator. (Total indicator reading)
• If it exceeds the limit, replace crankshaft.
CONNECTING ROD BEARING OIL CLEARANCE
Method by Calculation
Standard
: Refer to
JPBIA0228ZZ
JPBIA0229ZZ
Out-of-round (Difference between “c” and “d”)
: Refer to
Taper (Difference between “a”and “b”)
Standard and limit
: Refer to
.
SEM346D
EM-122
< UNIT DISASSEMBLY AND ASSEMBLY >
CYLINDER BLOCK
• Install connecting rod bearings (1) to connecting rod (2) and con-
necting rod cap, and tighten connecting rod bolts to the specified
torque. Refer to
EM-107, "Disassembly and Assembly"
for the
tightening procedure.
• Measure the inner diameter of connecting rod bearing with an inside micrometer.
(Oil clearance) = (Connecting rod bearing inner diameter) – (Crankshaft pin journal diameter)
• If the calculated value exceeds the limit, select proper connecting rod bearing according to connecting rod
big end diameter and crankshaft pin journal diameter to obtain the specified bearing oil clearance. Refer to
.
Method of Using Plastigage
• Remove oil and dust on crankshaft pin journal and the surfaces of each bearing completely.
• Cut a plastigage slightly shorter than the bearing width, and place it in crankshaft axial direction, avoiding oil
holes.
• Install connecting rod bearings to connecting rod and connecting rod bearing cap, and tighten connecting
rod bolts to the specified torque. Refer to
EM-107, "Disassembly and Assembly"
dure.
CAUTION:
Never rotate crankshaft.
• Remove connecting rod bearing cap and bearings, and using the
scale on the plastigage bag, measure the plastigage width.
NOTE:
The procedure when the measured value exceeds the limit is the
same as that described in the “Method by Calculation”.
MAIN BEARING OIL CLEARANCE
Method by Calculation
• Install main bearings (3) to cylinder block (1) and main bearing cap
(2), and tighten main bearing cap bolts to the specified torque.
Refer to
EM-107, "Disassembly and Assembly"
for the tightening
procedure.
• Measure the inner diameter of main bearing with a bore gauge.
(Oil clearance) = (Main bearing inner diameter) – (Crankshaft main
journal diameter)
• If the calculated value exceeds the limit, select proper main bear-
ing according to main bearing inner diameter and crankshaft main
journal diameter to obtain the specified bearing oil clearance.
Refer to
Method of Using Plastigage
• Remove engine oil and dust on crankshaft journal and the surfaces of each bearing completely.
JPBIA0230ZZ
Standard and limit
: Refer to
EM-142, "Connecting Rod Bearing"
.
JPBIA0231ZZ
Standard and limit
: Refer to
.
JPBIA0232ZZ
CYLINDER BLOCK
EM-123
< UNIT DISASSEMBLY AND ASSEMBLY >
C
D
E
F
G
H
I
J
K
L
M
A
EM
N
P
O
• Cut a plastigage slightly shorter than the bearing width, and place it in crankshaft axial direction, avoiding oil
holes.
• Install main bearing to cylinder block and main bearing cap, and tighten main bearing cap bolts with main
bearing cap to the specified torque. Refer to
EM-107, "Disassembly and Assembly"
dure.
CAUTION:
Never rotate crankshaft.
• Remove main bearing cap and bearings, and using the scale on
the plastigage bag, measure the plastigage width.
NOTE:
The procedure when the measured value exceeds the limit is the
same as that described in the “Method by Calculation”.
MAIN BEARING CRUSH HEIGHT
• When main bearing cap is removed after being tightened to the
specified torque with main bearings (1) installed, the tip end of
bearing must protrude. Refer to
for the tightening procedure.
• If the standard is not met, replace main bearings.
CONNECTING ROD BEARING CRUSH HEIGHT
• When connecting rod bearing cap is removed after being tightened
to the specified torque with connecting rod bearings (1) installed,
the tip end of bearing must protrude. Refer to
for the tightening procedure.
• If the standard is not met, replace connecting rod bearings.
MAIN BEARING CAP BOLT OUTER DIAMETER
• Measure the outer diameters (A), (B) at two positions as shown in
the figure.
• If reduction appears in (A) range, regard it (B).
• If it exceeds the limit (large difference in dimensions), replace main
bearing cap bolts with new one.
MAIN BEARING CAP SUB BOLT OUTER DIAMETER
JPBIA0231ZZ
A
: Crush height
Standard
: There must be crush height.
JPBIA0233ZZ
A
: Crush height
Standard
: There must be crush height.
JPBIA0233ZZ
c
: 20 mm (0.79 in)
d
: 55 mm (2.17 in)
e
: 12 mm (0.47 in)
Limit [(B) – (A)]
: 0.15 mm (0.0059 in)
JPBIA2280ZZ
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