Bearing Clearance

• Use either of the following two methods, however method "A" gives more reliable results and so is the preferred method.

Method A (Using Bore Gauge and Micrometer) 

Main Bearing 

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: Identifying Main Bearings

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. Measure the inner diameters "A" of each main bearing as shown.
   Fig 2: Measuring Inner Diameter Of Main Bearing Housing

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. Measure the outer diameters "Dm" of each crankshaft main journal as shown.
   Fig 3: Measuring Outer Diameters Of Crankshaft Main Journal

   Courtesy of NISSAN MOTOR CO., U.S.A.
5. Calculate the main bearing clearance.

   Main bearing clearance = "A" - "Dm" 

   Standard: 0.035 - 0.045 mm (0.0014 - 0.0018 in) 

   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.
     Fig 4: Measuring Crankshaft Journal Clearance

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

   "L": 0.10 mm (0.0039 in) 

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.
   Fig 5: Identifying Cylinder Bore And Bearing Housing Grade
   Courtesy of NISSAN MOTOR CO., U.S.A.
   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 6: Identifying Journal Diameter Grade Number

      Courtesy of NISSAN MOTOR CO., U.S.A.
   3. Select the main bearing suitable thickness according to the following table:
      Fig 7: Main Bearing Suitable Thickness Chart

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

Connecting Rod Bearing (Big End)

1. Install the connecting rod bearing to the connecting rod and cap.
2. Install the connecting rod cap to the connecting rod. Tighten to specification. Refer to "DISASSEMBLY AND ASSEMBLY ".
3. Measure the inner diameter "C" of each connecting rod (big end) as shown.
   Fig 8: Measuring Inner Diameter Connecting Rod (Big End)

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. Measure the outer diameter "Dp" of each crankshaft pin journal.
   Fig 9: Measuring Outer Diameter Crankshaft Pin Journal

   Courtesy of NISSAN MOTOR CO., U.S.A.
5. Calculate the connecting rod bearing clearance.

   Connecting rod bearing clearance = C - Dp 

   Standard: 0.020 - 0.045 mm (0.0008 - 0.0018 in) 

   Limit: 0.070 mm (0.0028 in) 

6. If the calculated clearance exceeds the specified limit, replace the bearings.
7. If the clearance cannot be adjusted within the standard of any bearing, grind the crankshaft journal and use undersized bearings.
8. If the crankshaft is replaced with a new one, select the connecting rod bearings according to the following table:

   Connecting Rod Bearing Grade Number (Identification Color) 

   CONNECTING ROD BEARING GRADE NUMBER CHART
   
   

   Crankshaft pin journal grade number	Connecting rod bearing grade number
   0	0 (black)
   1	1 (brown)
   2	2 (green)

   Fig 10: Identifying Journal Diameter Grade Number

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

   These numbers are punched in either Arabic or Roman numerals.

Method B (Using Plastigage) 

• Remove oil and dust on the crankshaft pin 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 the connecting rod bearings to the connecting rod cap, and tighten the connecting rod nuts to the specified torque.
  CAUTION: Never rotate the crankshaft.
• Remove the connecting rod cap and bearings, and using the scale on the Plastigage bag, measure the Plastigage width.
  Fig 11: Measuring Plastigage Width

  Courtesy of NISSAN MOTOR CO., U.S.A.
  NOTE: The procedure when the measured value exceeds the repair limit is same as that described in "Method A (Using Bore Gauge and Micrometer)".