Valve Guide

WARNING: This page is about a different variant/trim than selected.

Check the clearance between valve guide and valve stem. The clearance can be checked by measuring the outer diameter of valve stem with a micrometer and the inner diameter of valve guide with a caliper gauge respectively.
Clearance between the valve guide and valve stem:

Standard

Intake

0.030 - 0.057 mm (0.0012 - 0.0022 in)

Exhaust

0.040 - 0.067 mm (0.0016 - 0.0026 in)
If the clearance between valve guide and valve stem exceeds the standard, replace the valve guide or valve itself, whichever shows the greater amount of wear or damage. See the following procedure for valve guide replacement.
Valve guide inner diameter:

5.500 - 5.512 mm (0.2165 - 0.2170 in)

Valve stem outer diameters:

Intake

5.455 - 5.470 mm (0.2148 - 0.2154 in)

Exhaust

5.445 - 5.460 mm (0.2144 - 0.2150 in)
1. Place the cylinder head on ST1 with the combustion chamber upward so that valve guides fit the holes in ST1.
2. Insert the ST2 into valve guide and press it down to remove the valve guide.
  ST1 18250AA010 CYLINDER HEAD TABLE
  
  ST2 499765700 VALVE GUIDE REMOVER
  
  Fig 1: Inserting ST2 Into Valve Guide
  Courtesy of SUBARU OF AMERICA, INC.
3. Turn the cylinder head upside down and place the ST as shown in the figure.
  ST 18251AA050 VALVE GUIDE ADJUSTER (INTAKE SIDE)
  
  ST 18251AA060 VALVE GUIDE ADJUSTER (EXHAUST SIDE)
  
  Fig 2: Identifying Valve Guide Adjuster
  Courtesy of SUBARU OF AMERICA, INC.
4. Before installing a new valve guide, make sure that neither scratches nor damages exist on the inner surface of valve guide holes in cylinder head.
5. Put a new valve guide, coated with sufficient oil, in the cylinder head, and insert the ST1 into valve guide. Press in until the valve guide upper end is flush with the upper surface of ST2.
  ST1 499765700 VALVE GUIDE REMOVER
  
  ST2 18251AA050 VALVE GUIDE ADJUSTER (INTAKE SIDE)
  
  ST2 18251AA060 VALVE GUIDE ADJUSTER (EXHAUST SIDE)
  
  Fig 3: Inserting ST1 Into Valve Guide
  Courtesy of SUBARU OF AMERICA, INC.
6. Check the valve guide protrusion amount "L".
  Valve guide protrusion amount L:
  
  Intake
  
  8.6 - 9.0 mm (0.3386 - 0.3543 in)
  
  Exhaust
  
  10.7 - 11.1 mm (0.4213 - 0.4370 in)
7. Ream the inside of valve guide using ST. Put the ST in valve guide, and rotate the ST slowly clockwise while pushing it lightly. Bring the ST back while rotating it clockwise.
  ST 499765900 VALVE GUIDE REAMER
  NOTE:
  - Apply engine oil to the ST when reaming.
  - If the inner surface of valve guide is damaged, the edge of ST should be slightly ground with oil stone.
  - If the inner surface of valve guide becomes lustrous and the ST does not chip, use a new ST or remedy the ST.
8. After reaming, clean the valve guide to remove chips.
9. Recheck the contact condition between valve and valve seat after replacing the valve guide.