Main Bearing

WARNING: This page is about a different car, the 2008 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.

Set the main bearings in their proper positions on the cylinder block and the main bearing cap.
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 Bearing
Courtesy of NISSAN MOTOR CO., U.S.A.
Measure the inner diameters "A" of each main bearing as shown.

Fig 2: Checking Inner Diameter Of Main Bearing Housing
Courtesy of NISSAN MOTOR CO., U.S.A.
Measure the outer diameters "Dm" of each crankshaft main journal as shown.
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.
  
  Fig 3: Checking Outer Diameters Of Each Crankshaft Main Journal
  Courtesy of NISSAN MOTOR CO., U.S.A.
- 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: Measuring Crankshaft Journal
Courtesy of NISSAN MOTOR CO., U.S.A.
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: Checking Cylinder Bore Grade (1, 2 Or 3) On Rear Side Of Cylinder Block
  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 Stamped On Crankshaft Front Side To Column
  Courtesy of NISSAN MOTOR CO., U.S.A.
3. Select the main bearing suitable thickness according to the following table:
Fig 7: Main Bearing Selection Table
Courtesy of NISSAN MOTOR CO., U.S.A.