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Connecting Rod And Connecting Rod Bearing

  1. Check for bend or twist using a connecting rod aligner. If it exceeds the limit, replace the connecting rod.
    NOTE: Measurement should be performed at a temperature of 20°C (68°F).

    Bend or twist per 100 mm (3.9370 in) in length: 

    Limit 

    0.10 mm (0.0039 in)

    G13868174Courtesy of SUBARU OF AMERICA, INC.
  2. Check that the large or small end thrust surface of each connecting rod is not damaged.
  3. Check each connecting rod bearing for scar, peeling, seizure, melting or wear, etc.
  4. Check the thrust clearance of each connecting rod using a thickness gauge.
    NOTE: Measurement should be performed at a temperature of 20°C (68°F).
    1. Clean the #1 connecting rod bearing and the #1 pin of crankshaft, and apply engine oil to the #1 pin of crankshaft.
    2. Set the #1 connecting rod bearing to the #1 connecting rod and #1 connecting rod cap.
    3. Set the #1 connecting rod, #1 connecting rod cap and #1 connecting rod cap bolt to the #1 pin of crankshaft.
      NOTE:
      • Each connecting rod has its own mating cap. Make sure that they are assembled correctly by checking their matching symbol.
      • Use a new connecting rod cap bolt.
      • Apply a coat of engine oil to the #1 connecting rod cap bolt thread.
    4. Using ST, tighten the #1 connecting rod cap bolts to 10 N.m (1.0 kgf-m, 7.4 ft-lb) in numerical order as shown in the figure, then retighten the bolts to 22 N.m (2.2 kgf-m, 16.2 ft-lb) in numerical order as shown in the figure.
      CAUTION:
      • Make sure to hold the crankshaft securely during work.
      • When holding the crankshaft, be careful not to damage the crankshaft.

      Preparation tool: 

      ST: SOCKET (18270AA020)

      Fig 1: #1 Connecting Rod Cap Bolts (Tightening Sequence)
      G13224615Courtesy of SUBARU OF AMERICA, INC.
    5. Using the ST and angle gauge, tighten the #1 connecting rod cap bolts with torque of 135° - 140° in numerical order as shown in the figure.
      CAUTION:
      • Make sure to hold the crankshaft securely during work.
      • When holding the crankshaft, be careful not to damage the crankshaft.
      NOTE: Prevent angle gauge from rotating using a V-block, etc.

      Preparation tool: 

      ST: SOCKET (18270AA020)

      Fig 2: #1 Connecting Rod Cap Bolts (Tightening Sequence)
      G13224616Courtesy of SUBARU OF AMERICA, INC.
    6. In the same manner, install the #2, #3 and #4 connecting rods.
    7. Check the thrust clearance of each connecting rod using a thickness gauge. If it is not within the standard, replace the connecting rod.
      NOTE: Measure the thrust clearance of each connecting rod at several points, and replace the connecting rod if there is uneven wear.

      Connecting rod thrust clearance: 

      Standard 

      0.070 - 0.330 mm (0.0028 - 0.0130 in)

      G11253511Courtesy of SUBARU OF AMERICA, INC.
  5. Check the oil clearance on each connecting rod bearing using plastigage.
    NOTE: Measurement should be performed at a temperature of 20°C (68°F).
    1. Clean the #1 connecting rod bearing and the #1 pin of crankshaft.
    2. Set the #1 connecting rod bearing to the #1 connecting rod and #1 connecting rod cap.
    3. Place a plastigage across the #1 pin of crankshaft, and set the #1 connecting rod, #1 connecting rod cap and #1 connecting rod cap bolt to the #1 pin of crankshaft.
      NOTE:
      • Each connecting rod has its own mating cap. Make sure that they are assembled correctly by checking their matching symbol.
      • Use a new connecting rod cap bolt.
      • Apply a coat of engine oil to the #1 connecting rod cap bolt thread.
    4. Using ST, tighten the #1 connecting rod cap bolts to 10 N.m (1.0 kgf-m, 7.4 ft-lb) in numerical order as shown in the figure, then retighten the bolts to 22 N.m (2.2 kgf-m, 16.2 ft-lb) in numerical order as shown in the figure.
      CAUTION:
      • Make sure to hold the crankshaft securely during work.
      • When holding the crankshaft, be careful not to damage the crankshaft.
      • During tightening, be careful not to move the #1 connecting rod and the #1 connecting rod cap.

      Preparation tool: 

      ST: SOCKET (18270AA020)

      Fig 3: #1 Connecting Rod Cap Bolts (Tightening Sequence)
      G13224615Courtesy of SUBARU OF AMERICA, INC.
    5. Using the ST and angle gauge, tighten the #1 connecting rod cap bolts with torque of 135° - 140° in numerical order as shown in the figure.
      CAUTION:
      • Make sure to hold the crankshaft securely during work.
      • When holding the crankshaft, be careful not to damage the crankshaft.
      • During tightening, be careful not to move the #1 connecting rod and the #1 connecting rod cap.
      NOTE: Prevent angle gauge from rotating using a V-block, etc.

      Preparation tool: 

      ST: SOCKET (18270AA020)

      Fig 4: #1 Connecting Rod Cap Bolts (Tightening Sequence)
      G13224616Courtesy of SUBARU OF AMERICA, INC.
    6. Using the ST, loosen the #1 connecting rod cap bolt, and remove the #1 connecting rod cap bolt and #1 connecting rod cap.
      CAUTION:
      • Make sure to hold the crankshaft securely during work.
      • When holding the crankshaft, be careful not to damage the crankshaft.
      • During removal, be careful not to move the #1 connecting rod and the #1 connecting rod cap.

      Preparation tool: 

      ST: SOCKET (18270AA020)

      G13224620Courtesy of SUBARU OF AMERICA, INC.
    7. Determine oil clearance of the #1 connecting rod bearing by matching the widest point of the plastigage on #1 pin of crankshaft against scale printed on a package of the plastigage. If it is not within the standard, replace the #1 connecting rod bearing.
      NOTE: Measure the outer diameter of crankshaft pin using micrometer, and select the suitable size connecting rod bearing when replacing the connecting rod bearing.
      Unit: mm (in)
      Bearing Connecting rod bearing thickness (at center) Crankshaft pin outer diameter
      Connecting rod side Connecting rod cap side
      Standard Standard Standard
      Standard size 1.496 - 1.512
      (0.0589 - 0.0595)      		 1.492 - 1.508
      (0.0587 - 0.0594)      		 47.976 - 48.000
      (1.8888 - 1.8898)
      0.03
      (0.0012) Undersize      		 1.515 - 1.519
      (0.0596 - 0.0598)      		 1.511 - 1.515
      (0.0595 - 0.0596)      		 47.946 - 47.970
      (1.8876 - 1.8886)
      0.05
      (0.0020) Undersize      		 1.525 - 1.529
      (0.0600 - 0.0602)      		 1.521 - 1.525
      (0.0599 - 0.0600)      		 47.926 - 47.950
      (1.8868 - 1.8878)
      0.25
      (0.0098) Undersize      		 1.625 - 1.629
      (0.0640 - 0.0641)      		 1.621 - 1.625
      (0.0638 - 0.0640)      		 47.726 - 47.750
      (1.8790 - 1.8799)

      Connecting rod bearing oil clearance: 

      Standard 

      0.017 - 0.047 mm (0.0007 - 0.0019 in)

      G08317260Courtesy of SUBARU OF AMERICA, INC.
    8. Completely remove the plastigage.
    9. In the same manner, check oil clearance of the #2, #3 and #4 connecting rod bearings.
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