Main Bearing Oil Clearance Inspection

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Using a micrometer, measure the outer diameters of the inside main journal.

Fig 1: Identifying Outer Diameters Of Inside Main Journal
Courtesy of MAZDA MOTORS CORP.
Using a cylinder bore gauge, measure the inner diameter of the stationary gear main bearing.

Fig 2: Measuring Inner Diameter Of Stationary Gear Main Bearing
Courtesy of MAZDA MOTORS CORP.
Calculate the main bearing oil clearance from the main journal outer diameter and the main bearing inner diameter.
Main Bearing Oil Clearance = (Main Bearing Inner Diameter) - (Main Journal Outer Diameter)
- If it exceeds the maximum specification, replace the main bearing. (See MAIN BEARING REPLACEMENT .)
  - If the clearance is not within the specification after replacing the main bearing, replace the eccentric shaft.
Standard Main Bearing Oil Clearance
1. Standard Power
2. 0.045-0.085 mm {0.0018-0.0033 in}
High Power
1. 0.055-0.075 mm {0.0022-0.0029 in}
Maximum Main Bearing Oil Clearance
1. Standard Power
  1. 0.1 mm {0.0039 in}
2. High Power
  1. 0.1 mm {0.0039 in}
  Fig 3: Measuring Main Bearing Oil Clearance
  Courtesy of MAZDA MOTORS CORP.