Main Bearing Oil Clearance

Method by Calculation

• Install main bearings (3) to cylinder block (1) and main bearing cap (2), and tighten main bearing cap bolts to the specified torque. Refer to "DISASSEMBLY AND ASSEMBLY " for the tightening procedure.
  Fig 1: Installing Main Bearings To Cylinder Block

  Courtesy of NISSAN MOTOR CO., U.S.A.
• Measure the inner diameter of main bearing with a bore gauge. (Bearing oil clearance) = (Main bearing inner diameter) - (Crankshaft main journal diameter)

  Standard: 

  No. 1, 4 and 5 journals 

  : 0.024 - 0.034 mm (0.0009 - 0.0013 in) 

  No. 2 and 3 journals 

  : 0.012 - 0.022 mm (0.0005 - 0.0009 in) 

  Limit : 0.065 mm (0.0026 in) 

• If clearance exceeds the limit, select proper main bearing according to main bearing inner diameter and crankshaft main journal diameter to obtain specified bearing oil clearance. Refer to "HOW TO SELECT PISTON AND BEARING ".

Method of Using Plastigage

• Remove engine oil and dust on crankshaft main journal and the surfaces of each bearing completely.
• Cut a plastigage slightly shorter than the bearing width, and place it in crankshaft axial direction, avoiding oil holes.
• Install main bearings to cylinder block and main bearing cap, and tighten main bearing cap bolts to the specified torque. Refer to "DISASSEMBLY AND ASSEMBLY " for the tightening procedure.
  CAUTION: Never rotate crankshaft.
• Remove main bearing cap and bearings, and using the scale (A) on the plastigage bag, measure the plastigage width.
  NOTE: The procedure when the measured value exceeds the limit is same as that described in the "Method by Calculation".
  Fig 2: Measuring Plastigage Width

  Courtesy of NISSAN MOTOR CO., U.S.A.