MAZDA 626 1987 Manual Online

INSPECTION AND REPAIR 1 A
Stem tip
Margin
thickness
Valve face
angle
45°
86U01X-078
76G01A-055
(
—SY/ in
76G01A-056
Valve guide

-Valve stem
Clearance
V
Valve and Valve Guide
1. Inspect each valve for the following. Replace or
resurface if necessary.
(1) Damaged or bent stem
(2) Roughness or damage to face
(3) Damage or uneven wear of stem tip
2. Check the valve head margin thickness. Replace
if necessary
Margin thickness
IN : 0.5 mm (0.020 in) min.
EX: 1.0 mm (0.039 in) min.
3. Measure the valve length.
Length mm (in)
12-valve 8-valve
IN 115.81 (4.5594) 111.89 (4.4051)
EX 116.21 (4.5752) 111.69 (4.3972)
Measure the valve stem diameter.
Diameter mm (in)
12-valve 8-valve
IN 6.970-6 985
(0.2744-0.2750)
8.030—8.045
(0.3161-0.3167)
EX 6.965-6.980 (0.2742-0.2748) 8.025-8.040 (0.3159-0.3165)
5. Measure the valve guide inner diameter.
Inner diameter mm (in)
12-valve 8-valve
IN 7.01-7.03 (0.2760—0.2768) 8.07—8.09
(0.3177—0.3185)
EX 7.01-7.03
(0.2760-0.2768)
8.07-8.09
(0.3177-0.3185)
6. Measure the valve stem to guide clearance.
(1) Method No. 1
Subtract the outer diameter of the valve stem
from the inner diameter of the corresponding
valve guide.

86U01X-117

1A—49

INSPECTION AND REPAIR 1 A
86U01X-082
Valve guide
Cylinder head
76G01A-057
(2) Method No. 2
Measure the valve stem play at a point close
to the valve guide with the valve lifted slightly
off the valve seat.
Clearance
IN : 0.025—0.060 mm (0.0010—0.0024 in)
EX: 0.030—0.065 mm (0.0012—0.0026 in)
Maximum: 0.20 mm (0.0079 in)
7. If the clearance exceeds the maximum, replace the
valve and/or valve guide.
8. Check that the valve guide projection height
(dimension A in the figure). Replace if necessary.
Height:
19.8—20.3 mm (0.780—0.799 in)... 12-valve
19.1—19.6 mm (0.752—0.772 in)...8-valve
Replacement of valve guide
Note
Although the shapes of the intake and exhaust
valve guides are different, use the exhaust
valve guide on both sides as a replacement.
86U01X-214
Removal
1. Gradually heat the cylinder head in water to ap-
prox. 90°C (194°F).

76G01A-131

1A—50

INSPECTION AND REPAIR 1 A
12-valve:
8-valve:
49 0249 01 OA
49 0221 251A
76G01A-058
76G01A-059
V
86U01X-087
2. Remove the valve guide from the side opposite the
combustion chamber with the SST.
3. Remove the valve guide clip (8-valve).
Installation
1. Fit the clip onto the valve guide (8 valve).
2. Gradually heat the cylinder head in water to ap-
prox. 90°C (194°F).
3. Tap the valve guide in from the side opposite the
combustion chamber with the SST until the projec-
tion height is as specified.
Valve Seat
1. Inspect the contact surface of the valve seat and
valve face for the following.
(1) Roughness
(2) Damage
2. If necessary, resurface the valve seat with a 45°
valve seat cutter and/or resurface the valve face.
3. Apply a thin coat of prussian blue to the valve face.
4. Check the valve seating by rotating the valve
against the seat.
(1) If blue does not appear 360° around the valve
face, replace the valve.
(2) If blue does not appear 360° around the valve
seat, resurface the seat.

79G01C-053

1A—51

1A INSPECTION AND REPAIR
76G01A-128
86U01X-088
5. Check the seat contact width.
Width: 1.2—1.6 mm (0.047—0.063 in)
6. Check that the valve seating position is at the cen-
ter of the valve face.
(1) If the seating position is too high, correct the
valve seat with a 60° cutter and a 45° cutter.
(2) If the seating position is too low, correct the
valve seat with a 35° (IN) or 15° (EX) cutter
and a 45° cutter.
7. Seat the valve to the valve seat with a lapping
compound.
76G01A-060
8. Check the sinking of the valve seat.
Measure protruding length (dimension L) of each
valve stem.
Dimension L: 50.2 mm (1.976 in).... 12-valve
46.5 mm (1.831 in).... 8-valve
(1) If L is as below, it can be used as it is.
50.2—51.0 mm (1.976—2.008 in)..12-valve
46.5—48.0 mm (1.831—1.890 in).. 8-valve
(2) If L is as below, insert a spacer between the
spring seat and cylinder head to adjust.
51.0—51.7 mm (2.008—2.035 in)..12-valve
48.0—48.7 mm (1.890—1.917 in).. 8-valve
(3) If L is more than as below, replace the cylin-
der head.
51.7 mm (2.035 in) or more 12-valve
48.7 mm (1.917 in) or more 8-valve
1A—52

INSPECTION AND REPAIR 1 A
76G01A-062
86U01X-092
76G01A-063
A vl^k
L^-X
B As^
Valve Spring
1. Inspect each valve spring for cracks or damage.
2. Check the free length and angle. Replace if
necessary.
Free length mm (in)
Standard Minimum
12-valve IN 49.5 (1.949) 49.0 (1.929) 12-valve EX 50.4 (1.984) 48.7 (1.917)
I FE.Middle Outer 51.2 (2.016) 50.6 (1.992)
8-valve East General Inner 45.7 (1.799) 43.7 (1.720) 8-valve
Others Outer 52.0 (2.047) 51.5 (2.028) 8-valve
Others Inner 44.0 (1.732) 43.3 (1.705)
Angle: 1.8 mm (0.071 in) max.
Camshaft
1. Set the front and rear journals on V-blocks.
Check the camshaft runout. Replace if necessary.
Runout: 0.03 mm (0.0012 in) max.
2. Check the cam for wear or damage. Replace if
necessary.
3. Check the cam lobe height at the two points as
shown in the figure.
Height mm (in)
Standard Minimum
12-valve IN 41.340 (1.6276) 41.14 (1.620) 12-valve EX 41.847 (1.6476) 41.65 (1.640)
8-valve IN 38.157 (1.5022) 37.96 (1.494) 8-valve EX 38.160 (1.5024) 37.96 (1.494)
4. Measure wear of the journals in X and Y directions
at the two points as shown in the figure.
Diameter mm (in)
12-valve 8-valve
No. 1,5 31.940-31.965 (1.2575-1.2585) 31.940-32.035 (1.2575-1.2612)
No. 2,3,4 31.910-31.935 (1.2563-1.2573) 31.910-32.065 (1.2563—1.2624)
Out-of-round: 0.05 mm (0.002 in) max.
76G01A-129

1
A—53

INSPECTION AND REPAIR 1 A
mjjm
H D f IT~inr
86U01X-095
5. Measure the oil clearance of the camshaft and
camshaft caps.
(1) Remove any oil, or dirt from the journals and
bearing surface.
(2) Set the camshaft onto the cylinder head.
(3) Position plasti-gauge on top of the journals in
the axial direction.
(4) Place the camshaft caps and rocker arm shafts
in position, and tighten them to the specified
torque.
Tightening torque:
18—26
N
m (1.8—2.7 m-kg, 13—20 ft-lb)
(5) Remove the camshaft caps and measure the
oil clearance at each cap.
Oil clearance
Front and rear:
0.035—0.085 mm (0.0014—0.0033 in)
Center three journals:
0.065—0.115 mm (0.0026—0.0045 in)
Maximum: 0.15 mm (0.0059 in)
(6) If the oil clearance exceeds the maximum, re-
place the cylinder head.
86U01X-096
6. Measure the camshaft end play. If it exceeds the
maximum, replace the camshaft and/or the cylin-
der head.
End play:
0.08—0.16 mm (0.003—0.006 in)
Maximum: 0.20 mm (0.008 in)
86U01X-097

76G01A-131

1A—54
Rocker Arm and Rocker Arm Shaft
1. Check for wear or damage to the contact surface
of the rocker arm shaft and the rocker arm. Re-
place if necessary.
2. Check the oil clearance between the rocker arm
and shaft. Replace if necessary.
(1) Measure the rocker arm inner diameter.
Diameter:
19.000—19.033 mm (0.7480—0.7493 in)
...12-valve
16.000—16.027 mm (0.6299—0.6310 in)
... 8-valve

INSPECTION AND REPAIR 1 A
76G01A-065
76G01A-066
86U01X-100
(2) Measure the rocker arm shaft diameter.
Diameter:
18.959—18.980 mm (0.7464—0.7472 in)
...12 valve
15.966—15.984 mm (0.6286—0.6293 in)
... 8 valve
(3) Subtract the shaft diameter from the rocker arm
diameter.
Oil clearance mm (in)
Standard Maximum
12-valve 0.020-0.074
(0.0008-0.0029) 0.10 (0.0039)
8-valve 0.016-0.061 (0.0006-0.0024) 0.10 (0.0039)
Hydraulic Lash Adjuster (12-valve)
Check the HLA face for wear or damage. Replace
if necessary.
Caution
Do not remove the HLA unless necessary to
prevent damaging the O-ring.
Cylinder Block
1. Check the cylinder block. Repair or replace if
necessary.
(1) Leakage damage
(2) Cracks
(3) Scoring of wall
2. Measure the distortion of the top surface of the cyl-
inder block in the six directions as shown in the
figure.
Distortion: 0.15 mm (0.006 in) max.
3. If the distortion exceeds the maximum, repair by
grinding, or replace the cylinder block.
Grinding limit: 0.20 mm (0.008 in) max.

86U01X-117

1A—55

INSPECTION AND REPAIR 1 A
76G01A-067
4. Measure the cylinder bore in directions X and Y
at three levels in each cylinder as shown.
Cylinder bore mm (in)
Size Bore
FE
F8
Standard 86.000-86.019 (3.3858-3.3866) FE
F8 0.25 (0.010) oversize 86.250-86.269 (3.3957-3.3964) FE
F8 0.50 (0.020) oversize 86.500-86.519 (3.4055-3.4062)
F6
Standard 81.000-81.019 (3.1890-3.1897)
F6
0.25 (0.010) oversize 81.250-81.269 (3.1988-3.1996)
F6 0.50 (0.020) oversize 81.500-81.519 (3.2087-3.2094) F6
0,75 (0.030) oversize 81.750-81.769 (3.2185-3.2192)
F6
1.00 (0.039) oversize 82.000-82.019 (3.2283-3.2291)
(1) If the difference between the measurement A
and C exceeds the maximum taper, rebore the
cylinder to oversize.
Taper: 0.019 mm (0.0007 in) max.
79G01C-071
O ^ ^ o
^^——
(2) If the difference between the measurement X
and Y exceeds the maximum out-of-round, re-
bore the cylinder to oversize.
Out-of-round: 0.019 mm (0.0007 in) max.
Caution
The boring size should be based on the size
of an oversize piston and be the same for all
cylinders.
79G01C-072
5. If the upper part of the cylinder wall shows uneven
wear, remove the ridge with a ridge reamer.

86U01X-117

1A—56

INSPECTION AND REPAIR 1A
76G01A-068
Piston
1. Inspect the outer circumferences of all pistons for
seizure or scoring. Replace if necessary.
2. Measure the outer diameter of each piston at a right
angle (90°) to the piston pin, 18 mm (0.709 in)
below the oil ring land lower edge.
Piston diameter mm (in)
Size Diameter

LU
OO LL LL Standard 85.944-85.964 (3.3836-3.3844)
LU
OO LL LL 0.25 (0.010) oversize 86.194-86.214 (3.3935-3.3942)

LU
OO LL LL
0.50 (0.020) oversize 86 444-86.464 (3.4033-3.4041)
F6
Standard 80 944-80.964 (3.1868-3.1876)
F6
0.25 (0.010) oversize 81.194-81.214 (3.1966-3.1974)
F6 0.50 (0.020) oversize 81.444-81.464 (3.2065-3.2072) F6
0.75 (0.030) oversize 81.694-81.714 (3.2163-3.2171)
F6
1.00 (0.039) oversize 81.944-81.964 (3.2261-3,2269)
3. Check the piston to cylinder clearance.
ClGdrsncG1
0.036—0.075 mm (0.0014—0.0030 in)
Maximum: 0.15 mm (0.0059 in)
4. If the clearance exceeds the maximum, replace the
piston or rebore the cylinders to fit oversize pistons.
Caution
If the piston is replaced, replace the piston
rings also.
76G01A-130
Piston and Piston Ring
1. Measure the piston ring to ring land clearance
around the entire circumference using a new pis-
ton ring.
Clearance (Top and Second):
0.03—0.07 mm (0.001—0.003 in)
Maximum: 0.15 mm (0.006 in)
2. If the clearance exceeds the maximum, replace the
piston.
69G01A-125
1A—57

INSPECTION AND REPAIR 1 A
JT
I0J
'r-Sj&f-;:*::;^
.^Piston ring
'r-Sj&f-;:*::;^
.^Piston ring
'r-Sj&f-;:*::;^
.^Piston ring
86U01X-104
76G01A-069
86U01X-106
3. Inspect the piston rings for damage, abnormal
wear, or breakage. Replace if necessary.
4. Insert the piston ring into the cylinder by hand and
push it to the bottom of the ring travel in using the
piston.
5. Measure each piston ring end gap with a feeler
gauge. Replace if necessary.
End gap
Top : 0.20—0.35 mm (0.008—0.014 in)
Second: 0.15—0.30 mm (0.006—0.012 in)
Oil rail : 0.20—0.70 mm (0.008—0.028 in)
Maximum: 1.0 mm (0.039 in)
Piston and Piston Pin
1. Measure the piston pin hole diameter in X and Y
directions at four points.
Diameter:
21.988—21.998 mm (0.8657—0.8661 in)
2. Measure the piston pin diameter.
Diameter:
21.974—21.980 mm (0.8651—0.8654 in)
3. Determine the piston pin to piston clearance by
subtracting the two figures.
Clearance:
0.008—0.024 mm (0.0003—0.0009 in)
4. If the clearance exceeds the specification, replace
the piston and/or piston pin.
86U01X-117
1A—58