Valve Shim

WARNING: This page is about a different car, the 2012 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

Visually check the valve shim for damage.
Check the clearance between valve shim and valve stem end. Check the clearance between valve shim and valve stem end by measuring respectively the inner diameter of valve shim and the outer diameter of valve stem end.
1. Using a caliper gauge, measure the inner diameter of valve shim. If it is not within the standard, replace the valve shim.
  NOTE:
  - Measurement should be performed at a temperature of 20°C (68°F).
  - If the valve shim has to be replaced, check the cam clearance and replace with the suitable valve shim. < refer to WHEN TIMING CHAIN ASSEMBLY IS REMOVED , INSPECTION, Cam Clearance >
  Valve shim inner diameter:
  
  Standard
  
  5.500 - 5.560 mm (0.2165 - 0.2189 in)
  
  Fig 1: Measuring Inner Diameter Of Valve Shim Using Caliper Gauge
  Courtesy of SUBARU OF AMERICA, INC.
2. Measure the outer diameter of valve stem end with a micrometer. If it is not within the standard, replace the valve.
  NOTE:
  - Measurement should be performed at a temperature of 20°C (68°F).
  - If the valve is replaced, put a small amount of grinding compound on the valve seat surface of cylinder head, and lap the valve and valve seat surfaces. Replace with a new valve oil seal after lapping. For replacement of valve oil seal, refer to the "INTAKE VALVE OIL SEAL AND EXHAUST VALVE OIL SEAL". < refer to INTAKE VALVE OIL SEAL AND EXHAUST VALVE OIL SEAL , INSPECTION, Cylinder Head >
  Valve stem end outer diameter:
  
  Standard
  
  5.455 - 5.470 mm (0.2148 - 0.2154 in)
  
  Fig 2: Measuring Outer Diameter Of Valve Stem End With Micrometer
  Courtesy of SUBARU OF AMERICA, INC.
3. Calculate the clearance between valve shim and valve stem end. If the clearance exceeds the standard, replace the valve shim or valve, whichever shows the greater amount of wear or damage.
  NOTE:
  - If the valve is replaced, put a small amount of grinding compound on the valve seat surface of cylinder head, and lap the valve and valve seat surfaces. Replace with a new valve oil seal after lapping. For replacement of valve oil seal, refer to the "INTAKE VALVE OIL SEAL AND EXHAUST VALVE OIL SEAL". < refer to INTAKE VALVE OIL SEAL AND EXHAUST VALVE OIL SEAL , INSPECTION, Cylinder Head >
  - If the valve shim has to be replaced, check the cam clearance and replace with the suitable valve shim. < refer to WHEN TIMING CHAIN ASSEMBLY IS REMOVED , INSPECTION, Cam Clearance >
  Clearance between the valve shim and valve stem end:
  
  Standard
  
  0.030 - 0.105 mm (0.0012 - 0.0041 in)