Main Bearing Oil Clearance

Method of Measurement

• Install the main bearings to the cylinder block and main bearing cap. Measure the main bearing inside diameter with the bearing cap bolts tightened to the specified torque. Refer to "DISASSEMBLY AND ASSEMBLY ".

  (Oil clearance) = (Inside diameter of main bearing) - (Crankshaft journal diameter)

  Standard: No. 1 and 5 journals: 0.001 - 0.011 mm (0.00004 - 0.0004 in) 

  No. 2, 3 and 4 journals: 0.007 - 0.017 mm (0.0003 - 0.0007 in) 

  Limit: No. 1 and 5 journals: 0.021 mm (0.0008 in) 

  No. 2, 3 and 4 journals: 0.027 mm (0.0011 in) 

  Fig 1: Example Of Main Bearing Oil Clearance Dimensions

  Courtesy of NISSAN NORTH AMERICA, INC.
• If measured value exceeds the repair limit, select main bearings referring to the main bearing inside diameter and crankshaft journal diameter, so that the oil clearance satisfies the standard. Refer to "HOW TO SELECT PISTON AND BEARING ".

Method of Using Plastigage

• Remove oil and dust on the crankshaft journal and 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 the main bearings to the cylinder block and main bearing cap, and tighten the main bearing bolts to the specified torque.
  CAUTION: Do not rotate crankshaft with plastigage installed.
• Remove bearing cap and bearings. Measure plastigage width using the scale on the plastigage bag.

Fig 2: Measuring Bearing Width Using Plastigage

Courtesy of NISSAN NORTH AMERICA, INC.