Valve Guide

WARNING: This page is about a different car, the 2006 Subaru Outback. However, it is still accessible from the selected car via links, so may be relevant.

Check the clearance between valve guide and stem. The clearance can be checked by measuring respectively the outer diameter of valve stem and inner diameter of valve guide with a micrometer.
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 stem exceeds the standard, replace the valve guide or valve itself whichever shows greater amount of wear or damaged and etc. 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: Identifying ST1 18250Aa010 Cylinder Head Table And ST2 499765700 Valve Guide Remover
3. Turn the cylinder head upside down and place the ST as shown in the figure.
  ST 18251AA040 VALVE GUIDE ADJUSTER
  
  Fig 2: Identifying Valve Guide Adjuster ST 18251AA020 On Cylinder Head
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 cylinder, 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 18251AA040 VALVE GUIDE ADJUSTER
  
  Fig 3: Identifying Valve Guide Remover ST1 499767200 And Valve Guide Adjuster ST2 18251Aa020
6. Check the valve guide protrusion.
  Valve guide protrusion L:
  
  11.4 - 11.8 mm (0.449 - 0.465 in)
7. Ream the inside of valve guide using ST. Put the reamer in valve guide, and rotate the reamer slowly clockwise while pushing it lightly. Bring the reamer back while rotating it clockwise. After reaming, clean the valve guide to remove chips.
  ST 499765900 VALVE GUIDE REAMER
  NOTE:
  - Apply engine oil to the reamer when reaming.
  - If the inner surface of valve guide is damaged, the edge of reamer should be slightly ground with oil stone.
  - If the inner surface of valve guide becomes lustrous and the reamer does not chip, use a new reamer or remedy the reamer.
8. Recheck the contact condition between valve and valve seat after replacing the valve guide.