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Home >> Nissan-Datsun >> 2011 >> Sentra S >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (Engine Mechanical (Qr25DE)) >> Service Information >> Cylinder Block >> How to Select Piston and Bearing >> How To Select A Main Bearing

How To Select A Main Bearing

WARNING: This page is about a different variant/trim than selected.

When New Cylinder Block and Crankshaft are Used: 

  1. "Main Bearing Selection Table" rows correspond to bearing housing grade on rear left side of cylinder block.
    • If there is a corrected stamp mark on the cylinder block, use it as a correct reference.
      Fig 1: Location Of Stamp Mark On Cylinder Block
      G07137593Courtesy of NISSAN MOTOR CO., U.S.A.
  2. Apply pin diameter grade (B) stamped on crankshaft front side to column in "Main Bearing Selection Table".
    • A: Journal diameter grade
      Fig 2: Location Of Journal Diameter Grade
      G07137594Courtesy of NISSAN MOTOR CO., U.S.A.
  3. Find value at crossing of row and column in "Main Bearing Selection Table".
    CAUTION:
    • There are two main bearing selection tables. One is for odd-numbered journals (1, 3, and 5) and the other is for even-numbered journals (2 and 4). Make certain to use the appropriate table. This is due to differences in the specified clearances.
  4. Apply the symbol obtained to "Main Bearing Grade Table" to select.
    NOTE:
    • Service parts are available as a set of both upper and lower.

When Cylinder Block and Crankshaft are Reused: 

  1. Measure inner diameter of cylinder block main bearing housing and outer diameter of crankshaft journal.
  2. Apply measurement in above step  1 to the "Main Bearing Selection Table".
  3. Follow steps  3 and  4 in "When New Cylinder Block and Crankshaft are Used".

Main Bearing Selection Table (No. 1, 3, and No. 5 journals)

Fig 3: Main Bearing Selection Table (No. 1, 3, And No. 5 Journals)
G07137595Courtesy of NISSAN MOTOR CO., U.S.A.

Main Bearing Selection Table (No. 2, and 4 journals)

Fig 4: Main Bearing Selection Table (No. 2, And 4 Journals)
G07137596Courtesy of NISSAN MOTOR CO., U.S.A.
MAIN BEARING GRADE TABLE (ALL JOURNALS)

Unit: mm (in)
Grade number Thickness Identification color (UPR/LWR) Remarks
0 1.973 - 1.976 (0.0777 - 0.0778) Black Grade and color are the same for upper and lower bearings.
1 1.976 - 1.979 (0.0778 - 0.0779) Brown
2 1.979 - 1.982 (0.0779- 0.0780) Green
3 1.982 - 1.985 (0.0780 - 0.0781) Yellow
4 1.985 - 1.988 (0.0781 - 0.0783) Blue
5 1.988 - 1.991 (0.0783 - 0.0784) Pink
6 1.991 - 1.994 (0.0784 - 0.0785) Purple
01 UPR 1.973 - 1.976 (0.0777 - 0.0778) Black/Brown Grade and color are different for upper and lower bearings.
LWR 1.976 - 1.979 (0.0778 - 0.0779)
12 UPR 1.976 - 1.979 (0.0778 - 0.0779) Brown/Green
LWR 1.979 - 1.982 (0.0779 - 0.0780)
23 UPR 1.979 - 1.982 (0.0779 - 0.0780) Green/Yellow
LWR 1.982 - 1.985 (0.0780 - 0.0781)
34 UPR 1.982 - 1.985 (0.0780 - 0.0781) Yellow/Blue
LWR 1.985 - 1.988 (0.0781 - 0.0783)
45 UPR 1.985 - 1.988 (0.0781 - 0.0783) Blue/Pink
LWR 1.988 - 1.991 (0.0783 - 0.0784)
56 UPR 1.988 - 1.991 (0.0783 - 0.0784) Pink/Purple
LWR 1.991 - 1.994 (0.0784 - 0.0785)
67 UPR 1.991 - 1.994 (0.0784 - 0.0785) Purple/White
LWR 1.994 - 1.997 (0.0785 - 0.0786)

Use Undersize Bearing Usage Guide

BEARING UNDERSIZE TABLE

Unit: mm (in)
Size U.S. Thickness
0.25 (0.0098) 2.106 - 2.114 (0.0829 - 0.0832)
Fig 5: Identifying Crankshaft Pins And Journals
G07137597Courtesy of NISSAN MOTOR CO., U.S.A.
CAUTION: Do not damage fillet R when grinding crankshaft journal in order to use an undersize bearing (all journals).