Subaru 2002 IMPREZA Service Manual page 174

CYLINDER HEAD ASSEMBLY
MECHANICAL
2. VALVESEAT
Inspect the intake and exhaust valve seats, and
correct the contact surfaces with valve seat cutter if
they are defective or when valve guides are re-
placed.
Valve seat width: W
Intake
Standard
1.0 mm (0.039 in)
Limit
1.7 mm (0.067 in)
Exhaust
Standard
1.5 mm (0.059 in)
Limit
2.2 mm (0.087 in)
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G2M0761
3. VALVE GUIDE
1) Check the clearance between valve guide and
stem. The clearance can be checked by measuring
the outside diameter of valve stem and the inside
diameter of valve guide with outside and inside mi-
crometers respectively.
Clearance between the valve guide and valve
stem:
Standard
Intake
0.035
-
0.062 mm (0.0014
-
0.0024 in)
Exhaust
0.040
-
0.067 mm (0.0016
-
0.0026 in)
0.15 mm (0.0059 in)
Limit
2) If the clearance between valve guide and stem
exceeds the limit, replace the valve guide or valve
itself whichever shows greater amount of wear.
See the following procedure for valve guide re-
place men t.
Valve guide inner diameter:
Valve stem outer diameters:
6.000
-
6.012 mm (0.2362
-
0.2367 in)
Intake
5.950
-
5.965 mm (0.2343
-
0.2348 in)
Exhaust
5.945
-
5.960 mm (0.2341
-
0.2346 in)
(1) Place the cylinder head on STI with the
combustion chamber upward so that valve
guides enter the holes in ST1.
(2) Insert the ST2 into valve guide and press it
down to remove the valve guide.
ST1 498267600 CYLINDER HEAD TABLE
ST2 499767200 VALVE GUIDE REMOVER
(3) Turn the cylinder head upside down
place ST as shown in the figure.
and
ST 498767700 VALVE GUIDE ADJUSTER
L
(4) Before installing a new valve guide, make
sure that neither scratches nor damages exist
on the inside surface of the valve guide holes in
cylinder head.
ME(D0HC TURBO)-68