Oil Pump: Inspection

Check seal ring and O-ring oil seal for breaks or damage.
Check other parts for dents or abnormalities.
Selection of oil pump rotor assembly
1. Tip clearance
  Install inner rotor and outer rotor to oil pump. With rotor gears facing each other, measure crest-to-crest clearance.
  1. Tip clearance: 0.02 - 0.15 mm (0.0008 - 0.0059 in)
    
    Fig 1: Measuring Crest-To-Crest Clearance
    Courtesy of SUBARU OF AMERICA, INC.
2. Side clearance
  Set a depth gauge to oil pump housing, then measure oil pump housing-to-rotor clearances.
  1. Side clearance: 0.02 - 0.04 mm (0.0008 - 0.0016 in)
  Fig 2: Measuring Oil Pump Housing-To-Rotor Clearances
  Courtesy of SUBARU OF AMERICA, INC.
3. If depth and/or side clearances are outside specifications, replace rotor assembly.
  
  Fig 3: Oil Pump Rotor Assembly Specifications Chart
  Courtesy of SUBARU OF AMERICA, INC.
  - Measure the total end play and adjust to within specifications. Refer to ADJUSTMENT , Oil Pump.