Main Bearing

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.

Set main bearings in their proper positions on cylinder block and main bearing cap.

Fig 1: Identifying Oil Hole & Groove In Bearings
Courtesy of NISSAN MOTOR CO., U.S.A.
Install main bearing cap to cylinder block.
Tighten all bolts in correct order in two or three stages. Refer to ASSEMBLY .
Measure inner diameter "A" of each main bearing. Refer to Fig 2.

Fig 2: Measuring Inner Diameter Of Each Main Bearing
Courtesy of NISSAN MOTOR CO., U.S.A.
Measure outer diameter "Dm" of each main journal in crankshaft.

Fig 3: Measuring Outer Diameter Of Main Journal In Crankshaft
Courtesy of NISSAN MOTOR CO., U.S.A.
Calculate main bearing clearance.
Main bearing clearance = A - Dm

Standard: 0.018 - 0.042 mm (0.0007 - 0.0017 in)

Limit: 0.1 mm (0.004 in)

If it exceeds the limit, replace bearing.

If clearance cannot be adjusted within standard of any bearing, grind crankshaft journal and use undersized bearing.

When grinding crank pin and crank journal:
- Grind until clearance is within specified standard bearing clearance.
- Fillets should be finished as shown in Fig 4 . R: 2.3 - 2.5 mm (0.091 - 0.098 in)
  Refer to BEARING CLEARANCE , for standard bearing clearance and available spare parts.
  
  Fig 4: Graphing Main & Pin Journal Clearances
  Courtesy of NISSAN MOTOR CO., U.S.A.
If the crankshaft is replaced, select thickness of main bearings as follows
1. 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.
2. Grade number of each crankshaft main journal is punched on the respective crankshaft. These numbers are punched in either Arabic or Roman numerals.
  
  Fig 5: Locating Cylinder Block Grade Numbers
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 6: Locating Journal Grade Numbers
  Courtesy of NISSAN MOTOR CO., U.S.A.
3. Select main bearing with suitable thickness according to the following table.
  
  Fig 7: Identifying Main Bearing Grade Color Application Table
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 8: Locating Main Bearing Grade Colors
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  For example:
  
  Cylinder block main journal grade number: 1
  
  Crankshaft main journal grade number: 2
  
  Main bearing grade number = 1 + 2 = 3 (Yellow)
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