Mazda Engine SKYACTIV-G 2.5. Manual — part 11

MECHANICAL

01-10–28

4. Measure the inner diameter of each valve guide

using the caliper gauge. Measurement positions

total six and are in the X and Y directions, at three

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

• If it is not within the specification, replace the

valve guide.

Standard valve guide inner diameter

IN: 5.510—5.530 mm {0.2170—0.2177 in}

EX: 5.510—5.530 mm {0.2170—0.2177 in}

5. Calculate the clearance between the valve stem

and the valve guide by subtracting the inner

diameter of the valve guide from the outer

diameter of the corresponding valve stem.

• If it exceeds the maximum specification,

replace the valve or valve guide.

Standard clearance between valve stem and

guide

IN: 0.025—0.060 mm {0.0010—0.0023 in}

EX: 0.030—0.065 mm {0.0012—0.0025 in}

Maximum clearance between valve stem and

guide

0.10 mm {0.0039 in}

6. Measure the projection height (dimension A) of

each valve guide using the vernier caliper.

• If it is not within the specification, replace the

valve guide.

Standard valve guide projection height

IN: 16.4—17.0 mm {0.646—0.669 in}

EX: 16.4—17.0 mm {0.646—0.669 in}

End Of Sie

X

Y

A

B

C

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VALVE STEM

CLEARANCE

VALVE GUIDE

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VALVE GUIDE

CYLINDER HEAD

A

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MECHANICAL

01-10–29

01-10

VALVE GUIDE REPLACEMENT

id011000501200

Removal

1. Tap the valve guide out from combustion chamber

side using the

SST.

Installation

1. Apply clean engine oil to the valve guide.

2. Tap the valve guide from the camshaft side using

the SST so that the projection height (dimension

A) is within the specification.

Standard valve guide projection height

IN: 16.4—17.0 mm {0.646—0.669 in}

EX: 16.4—17.0 mm {0.646—0.669 in}

End Of Sie

VALVE SPRING INSPECTION

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Caution

• The valve springs differ depending on the

IN and EX sides.Therefore, verify the free

length or identification paint beforehand

and inspect the valve springs.

VALVE GUIDE

49 B012 015

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VALVE GUIDE

CYLINDER HEAD

A

49 B012 015

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48.96 mm {1.928 in}

IN

EX

50.07 mm {1.971 in}

NOT PAINTED

PURPLE PAINT

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MECHANICAL

01-10–30

1. Measure the valve spring height using the spring

tester.

• If it is not within the specification, replace the

valve spring.

Valve spring installation height

When pressurized with spring force of 228—

252 N {23.3—25.6 kgf, 51.3—56.6 lbf},

spring height is 38.0 mm {1.50 in}

2. Measure the amount of off-square on the valve

spring using a square.

(1) Rotate the valve spring one full turn and

measure A at the point where the gap is the

largest.

• If it exceeds the maximum specification,

replace the valve spring.

Maximum valve spring off-square

IN: 2.0 ° (1.7 mm {0.067 in})

EX: 2.0 ° (1.7 mm {0.067 in})

End Of Sie

CAMSHAFT INSPECTION

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1. Set the No.1 and No.5 journals of the camshaft on V-blocks.

2. Measure the camshaft runout using the dial

gauge.

• If it exceeds the maximum specification,

replace the camshaft.

Maximum camshaft runout

0.030 mm {0.0012 in}

3. Measure the cam height using the micrometer as

shown in the figure.

• If it is less than the minimum specification,

replace the camshaft.

Standard cam height

IN: 42.34 mm {1.667 in}

EX: 40.37 mm {1.589 in}

Minimum cam height

IN: 42.27 mm {1.664 in}

EX: 40.30 mm {1.587 in}

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A

UPPER

LOWER

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MECHANICAL

01-10–31

01-10

4. Measure the journal diameter using the

micrometer. Measurement positions total four and

are in the X and Y directions, at two points (A and

B) as shown in the figure.

• If it is less than the minimum specification,

replace the camshaft.

Standard camshaft journal diameter

24.96—24.98 mm {0.9827—0.9834 in}

Minimum camshaft journal diameter

24.93 mm {0.9815 in}

5. Measure the camshaft journal oil clearance using

the following procedure:

(1) Clean the camshaft journal and the journal receptacle part.

(2) Put the camshaft on the cylinder head with the rocker arm detached.

(3) Cut the plastigauge to the same length as the

journal width and position it parallel to the

camshaft.

(4) Install the camshaft caps. (See 01-10-59

CYLINDER HEAD ASSEMBLY (II).)

(5) Remove the camshaft caps. (See 01-10-14

CYLINDER HEAD DISASSEMBLY (I).)

(6) Measure the camshaft journal oil clearance.

• If it exceeds the maximum specification,

replace the cylinder head.

Standard camshaft journal oil clearance

0.035—0.080 mm {0.0014—0.0031 in}

Maximum camshaft journal oil clearance

0.090 mm {0.0035 in}

6. Measure the camshaft end play using a dial

gauge.

• If it exceeds the maximum specification,

replace the cylinder head or camshaft.

Standard camshaft end play

0.07—0.22 mm {0.003—0.008 in}

Maximum camshaft end play

0.23 mm {0.0091 in}

End Of Sie

A

B

X

Y

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PLASTIGAUGE

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