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Crankshaft & Main Bearings

  1. Main bearing cap bolts must be loosened evenly in 3 steps and proper sequence. See Fig 1 . Remove main bearing cap beam, located below main bearing caps.
    CAUTION: Ensure main bearing caps are marked for location and direction of installation for reassembly reference before removing. Main bearing caps must be installed in original locations.
  2. Ensure main bearing journal diameter, taper, runout and out-of-round are within specification. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS  table under ENGINE SPECIFICATIONS.
  3. If crankshaft main bearing journals must be ground for undersize main bearings, ensure main bearing journal fillet roll exceeds .004" (.10 mm). See Fig 2 .
    Fig 1: Main Bearing Bolt Removal & Installation Sequence
    G92C00457Courtesy of NISSAN MOTOR CO., U.S.A.
    Fig 2: Measuring Main Bearing Journal Fillet Roll
    G92D00458Courtesy of NISSAN MOTOR CO., U.S.A.
  4. If crankshaft is reused, select main bearing to obtain correct bearing clearance. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS  table.
  5. If crankshaft is replaced, note main bearing journal grade number marked on rear corner of cylinder block and on front of crankshaft. See Fig 3 .
    Fig 3: Identifying Main Bearing Journal Grade Number
    G92E00459Courtesy of NISSAN MOTOR CO., U.S.A.
  6. Using main journal grade numbers, determine main bearing grade number to be used. See MAIN BEARING APPLICATION  table. For example, if crankshaft grade number is 0 and cylinder block grade number is 0, use a grade number 0 main bearing with color code A-Black.
  7. Main bearing grade number can be identified by bearing color code. See MAIN BEARING SPECIFICATIONS table.
    MAIN BEARING APPLICATION

    Crankshaft Grade Number Cylinder Block Grade Number Bearing Number& Color Code
    0 0 0 (A-Black)
    0 1 1 (B-Brown)
    0 2 2 (C-Green)
    0 3 3 (D-Yellow)
    1 0 1 (B-Brown)
    1 1 2 (C-Green)
    1 2 3 (D-Yellow)
    1 3 4 (E-Blue)
    2 0 2 (C-Green)
    2 1 3 (D-Yellow)
    2 2 4 (E-Blue)
    2 3 5 (F-Pink)
    3 0 3 (D-Yellow)
    3 1 4 (E-Blue)
    3 2 5 (F-Pink)
    3 3 6 (G-None)
    MAIN BEARING SPECIFICATIONS

    Grade Number ID Mark & Color Code Bearing Thickness In. (mm)
    0 A-Black .0778-.0780 (1.976-1.981)
    1 B-Brown .0780-.0781 (1.981-1.983)
    2 C-Green .0781-.0782 (1.983-1.986)
    3 D-Yellow .0782-.0783 (1.986-1.989)
    4 E-Blue .0783-.0784 (1.989-1.992)
    5 F-Pink .0784-.0785 (1.992-1.995)
    6 G-None .0785-.0787 (1.995-1.999)
  8. Ensure main bearing caps are installed in original locations. Coat main bearing cap bolt threads and seat area of bolt with engine oil.
  9. With all main bearing caps and main bearing cap beam installed, move crankshaft forward and backward to align all main bearings. Tighten main bearing cap bolts to specification in sequence. See Fig 1 . See TORQUE SPECIFICATIONS  .
  10. Ensure crankshaft end play is within specification. See CRANKSHAFT, MAIN & CONNECTING ROD BEARINGS  table. Replace thrust bearing if crankshaft end play is not within specification.
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