Piston Pin & Connecting Rod Bushing

Check the connecting rod bushing for damage.
Check the clearance between piston pin and connecting rod bushing. Check the clearance between piston pin and connecting rod bushing by measuring the outer diameter of piston pin and the inner diameter of connecting rod bushing respectively.
1. Measure the outer diameter of piston pin with a micrometer.
  NOTE:
  - Measurement should be performed at a temperature of 20°C (68°F).
  - Measure the outer diameter of the piston pin at the two locations as shown in the figure, and read the value of most worn location.
  - Record the measured value.
    
    Fig 1: Measuring Outer Diameter Of Piston Pin
    Courtesy of SUBARU OF AMERICA, INC.
2. Using a caliper gauge, measure the inner diameter of connecting rod bushing.
  NOTE:
  - Measurement should be performed at a temperature of 20°C (68°F).
  - Measure the inner diameter of the connecting rod bushing at the two locations as shown in the figure, and read the value of most worn location.
  - Record the measured value.
    
    Fig 2: Measuring Inner Diameter Of Connecting Rod Bushing Using Caliper Gauge
    Courtesy of SUBARU OF AMERICA, INC.
3. Calculate the clearance between piston pin and connecting rod bushing.
  Clearance between piston pin and connecting rod bushing:
  
  Standard
  
  0.004 - 0.026 mm (0.0002 - 0.0010 in)
If the clearance between piston pin and connecting rod bushing is not within the standard, replace the connecting rod bushing and piston pin as a set. For replacement procedure of connecting rod bushing, refer to the following.
1. Remove the connecting rod bushing from connecting rod small end with ST and press.
  NOTE: Be careful not to confuse the direction of the ST, because it is used in opposite directions for extraction and press-fit.
  
  ST 18350AA000 CONNECTING ROD BUSHING REMOVER AND INSTALLER
  
  Fig 3: Removing Connecting Rod Bushing From Connecting Rod Small End
  Courtesy of SUBARU OF AMERICA, INC.
2. Press the connecting rod bushing with ST and the press, after applying engine oil on the periphery of connecting rod bushing.
  NOTE:
  - Position the clinch portion of connecting rod bushing as shown in the figure.
    
    Fig 4: Identifying Connecting Rod Bushing Clinch Portion
    Courtesy of SUBARU OF AMERICA, INC.
  - Be careful not to confuse the direction of the ST, because it is used in opposite directions for extraction and press-fit.
  ST 18350AA000 CONNECTING ROD BUSHING REMOVER AND INSTALLER
  
  Fig 5: Removing Connecting Rod Bushing From Connecting Rod Small End Using Tool
  Courtesy of SUBARU OF AMERICA, INC.
3. Make two 3 mm (0.12 in) holes in the pressed connecting rod bushing by aligning with the pre-manufactured holes on the connecting rod small end.
4. Ream the inside of connecting rod bushing using the reamer. Insert the reamer in the connecting rod bushing, and turn slowly clockwise while pushing lightly. Bring the reamer back while rotating it clockwise.
  NOTE:
  - Use a ø22 reamer.
  - Apply engine oil to the reamer.
  - 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 connecting rod bushing becomes lustrous and the reamer does not chip, use a new reamer or remedy the reamer.
5. After completion of reaming, clean the connecting rod bushing to remove chips.