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 

EM-137,

"Cylinder Block"

.

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 

EM-137, "Cylinder Block"

.

Standard

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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)

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Standard and limit

: Refer to 

EM-137, "Cylinder Block"

.

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 

EM-137, "Cylinder Block"

.

CYLINDER BLOCK

EM-121

< UNIT DISASSEMBLY AND ASSEMBLY >

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• If out of the standard, measure the main bearing oil clearance. Then use undersize bearing. Refer to 

EM-

128, "Main Bearing"

.

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 

EM-126,

"Connecting Rod Bearing"

.

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 

EM-128, "Main Bearing"

 and/or 

EM-126,

"Connecting Rod Bearing"

.

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 

EM-137, "Cylinder Block"

.

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Out-of-round (Difference between “c” and “d”)

: Refer to 

EM-137, "Cylinder Block"

.

Taper (Difference between “a”and “b”)

Standard and limit

: Refer to 

EM-137, "Cylinder Block"

.

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

EM-125, "Description"

.

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"

 for the tightening proce-

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 

EM-125, "Description"

.

Method of Using Plastigage

• Remove engine oil and dust on crankshaft journal and the surfaces of each bearing completely. 

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Standard and limit

: Refer to 

EM-142, "Connecting Rod Bearing"

.

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Standard and limit

: Refer to 

EM-141, "Main Bearing"

.

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CYLINDER BLOCK

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• 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"

 for the tightening proce-

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 

EM-107, "Disassembly and

Assembly"

 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 

EM-107, "Disassem-

bly and Assembly"

 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

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A

: Crush height

Standard

: There must be crush height.

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A

: Crush height

Standard

: There must be crush height.

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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)

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