Valve & Valve Shim

Visually check the valve shim for damage.
Check the clearance between valve and valve shim. Check the clearance between valve and valve shim by measuring the outer diameter of valve stem end and the inner diameter of valve shim respectively.
1. 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).
  - Measure the outer diameter of the valve stem end at the two locations as shown in the figure, and read the value of most worn location.
  - When the valve is replaced, lap the valve. Refer to VALVE SEAT for lapping.
  Valve stem end outer diameter:
  
  Intake
  
  Standard
  
  5.455 - 5.470 mm (0.2148 - 0.2154 in)
  
  Exhaust
  
  Standard
  
  5.445 - 5.460 mm (0.2144 - 0.2150 in)
  
  Fig 1: Measuring Valve Stem End Outer Diameter
  Courtesy of SUBARU OF AMERICA, INC.
2. 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).
  - Measure the inner diameter of the valve shim at the two locations as shown in the figure, and read the value of most worn location.
  - 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 .
  Valve shim inner diameter:
  
  Standard
  
  5.500 - 5.560 mm (0.2165 - 0.2189 in)
  
  Fig 2: Measuring Valve Shim Inner Diameter
  Courtesy of SUBARU OF AMERICA, INC.
3. Calculate the clearance between valve and valve shim. If the clearance exceeds the standard, replace the valve or valve shim, whichever shows the greater amount of wear or damage.
  NOTE:
  - When the valve is replaced, lap the valve. Refer to VALVE SEAT for lapping.
  - 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 .
  Clearance between valve and valve shim:
  
  Intake
  
  Standard
  
  0.030 - 0.105 mm (0.0012 - 0.0041 in)
  
  Exhaust
  
  Standard
  
  0.040 - 0.115 mm (0.0016 - 0.0045 in)