Main Bearing Oil Clearance

Method by Calculation

• Install main bearings (3) to cylinder block (1) and lower cylinder block (2), and tighten lower cylinder block bolts to the specified torque. Refer to "DISASSEMBLY AND ASSEMBLY " for the tightening procedure.
• Measure the inner diameter of main bearing with a bore gauge.

  (Oil clearance) = (Main bearing inner diameter) - (Crankshaft main journal diameter)

  Standard and limit: Refer to  "MAIN BEARING ".

• If the calculated value exceeds the limit, select proper main bearing according to main bearing inner diameter and crankshaft main journal diameter to obtain the specified bearing oil clearance. Refer to "DESCRIPTION ".
  Fig 1: Identifying Main Bearing Inner Diameter

  Courtesy of NISSAN NORTH AMERICA, INC.

Method of Using Plastigage

• Remove engine oil and dust on crankshaft 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 bearing to cylinder block and lower cylinder block, and tighten lower cylinder block bolts with lower cylinder block to the specified torque. Refer to "DISASSEMBLY AND ASSEMBLY " for the tightening procedure.
  CAUTION: Never rotate crankshaft.
• Remove lower cylinder block and bearings, and using the scale 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 Using Scale On Plastigage Bag

  Courtesy of NISSAN NORTH AMERICA, INC.