Mazda engine L8, LF, L3. Manual - part 8

B–12

ENGINE 

CYLINDER HEAD INSPECTION

A6E242410100E01

1. Carry out color contrast penetrate examination on the cylinder head surface. 

•

Replace the cylinder head if necessary.

2. Inspect for the following and repair or replace if necessary.

(1) Sunken valve seats
(2) Excessive camshaft oil clearance and end play

3. Measure the cylinder head for distortion in the six 

directions as shown.

•

If the distortion exceeds the maximum, 
replace the cylinder head.

Maximum distortion:

 0.10 mm {0.004 in}

4. Measure the manifold contact surface distortion 

as shown.

•

If the distortion exceeds the maximum, grind 
the surface or replace the cylinder head.

Maximum distortion:

0.10 mm {0.004 in}

Maximum grinding:

0.15 mm {0.006 in}

End Of Sie

VALVE, VALVE GUIDE INSPECTION

A6E242412111E01

1. Measure the valve head margin thickness of each 

valve. 

•

If not specified, replace the valve.

Margin thickness:

IN: 1.62 mm {0.0637 in}
EX: 1.82 mm {0.0716 in}

2. Measure the length of each valve. Replace the 

valve if necessary.

•

If not specified, replace the valve.

Standard length L:

IN: 102.99—103.79 mm {4.055—4.086 in}
EX: 104.25—105.05 mm {4.105—4.135 in}

Minimum length L:

IN: 102.99 mm {4.055 in}
EX: 103.79 mm {4.086 in}

AME2224E317

AME2224E318

AME2224E070

AME2224E071

ENGINE 

B–13

B

3. Measure the stem diameter of each valve in X 

and Y directions at the three points (A, B, and C) 
as indicated in the figure. 

•

If not as specified, replace the valve.

Standard diameter:

IN: 5.470—5.485 mm {0.2154—0.2159 in}
EX: 5.465—5.480 mm {0.2152—0.2157 in}

Maximum diameter:

IN: 5.440 mm {0.2142 in}
EX: 5.435 mm {0.2140 in}

4. Measure the inner diameter of each valve guide 

in X and Y directions at the three points (A, B, and 
C) as indicated in the figure. 

•

If not as specified, replace the valve guide.

Standard Inner diameter:

IN: 5.509—5.539 mm {0.2169—0.2180 in}
EX: 5.509—5.539 mm {0.2169—0.2180 in}

5. Calculate the valve stem to guide clearance by 

subtracting the outer diameter of the valve stem 
from the inner diameter of the corresponding 
valve guide. 

•

If not as specified, replace the valve and/or 
the valve guide.

Standard clearance:

IN: 0.024—0.069 mm {0.0009—0.0027 in}
EX: 0.029—0.074 mm {0.0012—0.0029 in}

Maximum clearance:

0.10 mm {0.004 in}

6. Measure the protrusion height (dimension A) of 

each valve guide without lower valve spring seat.

•

If not as specified, replace the valve guide.

Standard diameter:

IN: 12.2—12.8 mm {0.481—0.503 in}
EX: 12.2—12.8 mm {0.481—0.503 in}

End Of Sie

AME2224E313

AME2224E314

AME2224E315

AME2224E073

B–14

ENGINE 

VALVE GUIDE REPLACEMENT

A6E242412111E04

Valve Guide Removal

1. Remove the valve guide from the combustion 

chamber side using the SST.

Valve Guide Installation

1. Assemble the SSTs so that depth L is as 

specified.

Depth L:

IN: 12.2—12.8 mm {0.481—0.501 in}
EX: 12.2—12.8 mm {0.481—0.501 in}

2. Tap the valve guide in from the side opposite the 

camshaft side until the SSTs contacts the cylinder 
head.

3. Verify that the valve guide projection height 

(dimension A ) is within the specification.

Standard height:

IN: 12.2—12.8 mm {0.481—0.501 in}
EX: 12.2—12.8 mm {0.481—0.501 in}

End Of Sie

AME2224E312

AME2224E107

AME2224E018

AME2224E073

ENGINE 

B–15

B

VALVE SEAT INSPECTION/REPAIR

A6E242410102E01

1. Measure the seat contact width.

•

 If necessary, resurface the valve seat using a 
45

°

 valve seat cutter and/or resurface the 

valve face.

Standard width:

1.2—1.6 mm {0.048—0.062 in}

2. Verify that the valve seating position is at the 

center of the valve face.

(1) If the seating position is too out side, correct 

the valve seat using a 70

°°°°

 (IN) or 65

°°°°

 (EX) 

cutter, and a 45

°°°°

 cutter.

(2) If the seating position is too inner side, correct 

the valve seat using a 30

°°°°

 (IN) cutter, and a 

0

°°°°

 (EX) cutter, and a 45

°°°°

 cutter.

3. Inspect the sinking of the valve seat. Measure the 

protruding length (dimension L) of the valve stem.

•

If not specified, replace the cylinder head.

Standard dimension L:

IN: 40.64—42.24 mm {1.600—1.662 in}

EX: 40.50—42.10 mm {1.595—1.657 in}

End Of Sie

VALVE SPRING INSPECTION

A6E242412125E01

1. Apply pressing force to the pressure spring and 

inspect the spring height. 

•

If not as specified, replace the valve spring.

Pressing force:

494.9 N {50.47 kgf, 111.2 lbf}

Standard height:

27.80 mm {1.094 in}

AME2224E316

AME2224E020

AME2224E079

AME2224E308