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Home >> Nissan-Datsun >> 2004 >> Altima S, Standard >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (Engine Mechanical - 3.5L) >> Cylinder Block >> Inspection >> Bearing Clearance >> Method A (Using Bore Gauge and Micrometer) >> Main Bearing

Main Bearing

WARNING: This page is about a different variant/trim than selected.
  1. Set the main bearings in their proper positions on the cylinder block and the main bearing cap.
  2. Install the main bearing caps and bearing beam to the cylinder block. Tighten all bolts in the numerical order as specified. Refer to DISASSEMBLY AND ASSEMBLY  .
    Fig 1: View Of Main Bearings
    G02110779Courtesy of NISSAN MOTOR CO., U.S.A.
  3. Measure the inner diameters "A" of each main bearing as shown.
    Fig 2: Checking Bearing Clearance Using Bore Gauge And Micrometer
    G02110780Courtesy of NISSAN MOTOR CO., U.S.A.
  4. Measure the outer diameters "Dm" of each crankshaft main journal as shown.
    5. Fig 3: Checking Outer Diameters Of Crankshaft Main Journal
    G02110781Courtesy of NISSAN MOTOR CO., U.S.A.
  5. Calculate the main bearing clearance.

    Main bearing clearance = "A"-"Dm" 

    1. Standard : 0.035-0.045 mm (0.0014-0.0018 in) 
    2. Limit : 0.065 mm (0.0026 in) 
    • If it exceeds the limit, replace the bearing.
    • If clearance cannot be adjusted using any standard bearing grade, grind crankshaft journal and use an undersized bearing.
    • When grinding the crankshaft journal, confirm that the "L" dimension in the fillet role is more than the specified limit.

      "L" : 0.1 mm (0.004 in) 

      Fig 4: Checking Fillet
      G02110782Courtesy of NISSAN MOTOR CO., U.S.A.

  6. If the crankshaft or the cylinder block is replaced with a new one, select thickness of the main bearings as follows:
    1. The grade number of each cylinder block main journal is punched on the respective cylinder block. These numbers are punched in either Arabic or Roman numerals. If measured diameter is out of the grade punched, decide suitable grade from available main bearings.
    2. The grade number of each crankshaft main journal is punched on the crankshaft end. These numbers are punched in either Arabic or Roman numerals. If measured diameter is out of grade punched, decide the suitable grade from available main bearings.
      Fig 5: Locating Crankshaft Grade Numbers
      G02110784Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Select the main bearing suitable thickness according to the following table:
    Fig 6: View Of Main Bearing Selection Table
    G02110785Courtesy of NISSAN MOTOR CO., U.S.A.
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