Mazda Engine SKYACTIV-G 2.5. Manual - part 12

 

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Mazda Engine SKYACTIV-G 2.5. Manual - part 12

 

 

MECHANICAL 

01-10–32

CYLINDER BLOCK INSPECTION

id011000507200

1. Measure the cylinder block for distortion in six 

directions as shown in the figure using a straight 

edge and feeler gauge.

• If it exceeds the maximum specification, 

replace the cylinder block.

Maximum distortion, head gasket side of the 

cylinder block

0.10 mm {0.0039 in}

2. Measure the cylinder bore diameter using the 

cylinder gauge. The measurement position is in 

the X and Y directions at a point 

43.9 mm {1.73 

in} below the top surface of the cylinder as shown 

in the figure.

• If it is not within the specification, replace the 

cylinder block.

Standard cylinder bore diameter

89.000—89.030 mm {3.5040—3.5051 in}

End Of Sie

OIL JET VALVE INSPECTION

id011000505900

1. Apply compressed air to oil jet valve A and verify 

that air passes through oil jet valve B.

• If air does not flow, replace the oil jet valve.

• If there is air flow with air compressor of less 

than 

180 kPa {1.84 kgf/cm

2

, 26.1 psi}, 

replace the oil jet valve.

Oil jet valve opening pressure

180—220 kPa {1.84—2.24 kgf/cm

2

, 26.2—

31.9 psi}

End Of Sie

PISTON INSPECTION

id011000502100

Caution

• If the piston is replaced, replace the piston, piston pin, and the snap ring as a single component.

1. Measure the piston outer diameter using the 

micrometer. The measurement position is 

8.0 mm 

{0.31 in} from the lower end of the piston (area 

with no coating on the piston skirt) and in the 

thrust direction.

• If it is not within the specification, replace the 

piston.

Standard piston outer diameter

88.965—88.995 mm {3.5026—3.5037 in}

2. Measure the cylinder bore diameter. (See 01-10-

32 CYLINDER BLOCK INSPECTION.)

bp31je00000144

43.9 mm {1.73 in}

X

Y

bpe2ue00000098

A

B

bp31je00000131

bpe1ze00000097

MECHANICAL 

01-10–33

01-10

3. Calculate the cylinder-to-piston clearance from the cylinder bore diameter and the piston outer diameter.

• If the clearance exceeds the maximum specification, replace the piston or cylinder block.

Standard clearance between piston and cylinder

0.025—0.045 mm {0.0010—0.0017 in}

Maximum clearance between piston and cylinder

0.066 mm {0.0026 in}

4. Measure the piston-to-ring groove clearance 

along the perimeter using a feeler gauge. For the 

O-ring, measure the clearance with the O-ring 

assembled to the piston.

• If the clearance exceeds the maximum 

specification, replace the piston or piston ring.

Standard clearance between piston ring and 

ring groove

Top: 0.04—0.08 mm {0.002—0.003 in}

Second: 0.03—0.07 mm {0.0012—0.0027 in}

Oil: 0.04—0.12 mm {0.002—0.004 in}

Maximum clearance between piston ring and 

ring groove

Top: 0.12 mm {0.0047 in}

Second: 0.10 mm {0.0039 in}

Oil: 0.17 mm {0.0067 in}

End Of Sie

PISTON RING INSPECTION

id011000592300

1. Using the piston, press the piston ring parallel into 

the cylinder to 

43.9 mm {1.73 in} from the upper 

end of the cylinder block.

2. Measure the piston ring end gap using a feeler 

gauge.

• If it exceeds the maximum specification, 

replace the piston ring.

Standard piston ring end gap

Top: 0.13—0.18 mm {0.0052—0.0070 in}

Second: 0.18—0.28 mm {0.008—0.011 in}

Oil (Rail): 0.10—0.35 mm {0.004—0.013 in}

Maximum piston ring end gap

Top: 0.35 mm {0.014 in}

Second: 0.45 mm {0.018 in}

Oil (Rail): 0.52 mm {0.020 in}

End Of Sie

bpe1ze00000098

PISTON RING

PISTON

CYLINDER BLOCK

43.9 mm {1.73 in}

bpe2ue00000094

PISTON RING

bpe2ue00000095

MECHANICAL 

01-10–34

PISTON PIN INSPECTION

id011000507500

Caution

• If the piston or piston pin is replaced, replace the piston, piston pin and the snap ring as a single 

component.

1. Measure the piston pin outer diameter using the 

micrometer. Measurement positions total eight 

and are in the X and Y directions, at four points 

(A, B, C, and D) as shown in the figure.

Standard piston pin outer diameter

20.995—21.000 mm {0.82658—0.82677 in}

2. Measure the piston pin hole diameter using the 

caliper gauge. Measurement positions total eight 

and are in the X and Y directions, at four points 

(A, B, C, and D) as shown in the figure.

Standard piston pin hole diameter

21.004—21.008 mm {0.82693—0.82708 in}

3. Calculate the clearance between the piston pin 

hole diameter and the piston pin outer diameter.

• If it is not within the specification, replace the 

piston or the piston pin.

Standard clearance between piston pin hole 

diameter and piston pin outer diameter

0.004—0.013 mm {0.0002—0.0005 in}

4. Measure the inner diameter on the small end of 

the connecting rod using the caliper gauge in the 

X and Y directions as shown in the figure.

Standard connecting rod small end inner 

diameter

21.002—21.013 mm {0.82686—0.82728 in}

5. Calculate the clearance between the inner 

diameter on the small end of the connecting rod 

and the piston pin outer diameter.

• If it is not within the specification, replace the 

connecting rod or the piston pin.

Standard clearance between connecting rod small end inner diameter and piston pin outer diameter

0.002—0.018 mm {0.00008—0.00070 in}

End Of Sie

A
B

C

D

X

Y

adj2224e255

A
B

C
D

X

Y

bpe1ze00000085

X

Y

CONNECTING ROD

bpe2ue00000092

MECHANICAL 

01-10–35

01-10

PISTON AND CONNECTING ROD INSPECTION

id011000503100

1. Check the oscillation torque as shown in the 

figure. Verify that the large end drops under its 

own weight with no resistance.

• If the piston shakes heavily or unsmoothly, 

disassemble the piston and connecting rod, 

then inspect the following: (See 01-10-34 

PISTON PIN INSPECTION.)

—

Clearance between piston pin outer 

diameter and piston pin hole diameter.

—

Clearance between piston pin outer 

diameter and connecting rod small end 

inner diameter.

End Of Sie

CONNECTING ROD INSPECTION

id011000502800

1. Inspect the connecting rod for bending and 

distortion using the connecting rod aligner.

• If it exceeds the maximum specification, 

replace the connecting rod.

Maximum connecting rod bending

0.050 mm {0.0020 in}

Maximum connecting rod distortion

0.050 mm {0.0020 in}

Connecting rod center-to-center distance

154.8 mm {6.094 in}

End Of Sie

CONNECTING ROD CLEARANCE INSPECTION

id011000507600

1. Measure the side clearance at the large end of 

the connecting rod using a feeler gauge.

• If it exceeds the maximum specification, 

replace the connecting rod or crankshaft.

Standard side clearance at the large end of 

connecting rod

0.14—0.36 mm {0.006—0.014 in}

Maximum side clearance at the large end of 

connecting rod

0.465 mm {0.0183 in}

2. Measure the oil clearance at the large end of the 

connecting rod using the following procedure:

(1) Cut the plastigauge as wide as the connecting 

rod bearing width, place it parallel to the 

crankshaft, avoiding the oil hole.

(2) Install the lower connecting rod bearing and 

connecting rod cap. (See 01-10-40 

CYLINDER BLOCK ASSEMBLY (I).)

(3) Remove the connecting rod cap. (See 01-10-

22 CYLINDER BLOCK DISASSEMBLY (II).)

(4) Measure the oil clearance at the large end of 

the connecting rod.

• If it exceeds the maximum specification, 

replace the bearing or grind the crank pin 

and use oversize bearings so that the 

specified clearance is obtained.

bp31je00000061

bpe2ue00000036

bp31je00000148

PLASTIGAUGE

bpe2ue00000093

 

 

 

 

 

 

 

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