Oil Pump Overhaul: Inspection

Remove the screws from the pump housing, then separate the pump housing and the cover.
Check the inner-to-outer rotor radial clearance between the inner rotor (A) and outer rotor (B). If the inner-to-outer rotor clearance exceeds the service limit, replace the oil pump assembly.
Inner Rotor-to-Outer Rotor Radial Clearance

Standard (New): 0.04-0.16 mm (0.002-0.006 in.)

Service Limit: 0.20 mm (0.008 in.)

Fig 1: Identifying Inner-To-Outer Rotor Radial Clearance
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check the pump housing-to-rotor axial clearance between the rotors (A) and pump housing (B). If the pump housing-to-rotor axial clearance exceeds the service limit, replace the oil pump assembly.
Pump Housing-to-Rotor Axial Clearance

Standard (New): 0.02-0.07 mm (0.001-0.003 in.)

Service Limit: 0.12 mm (0.005 in.)

Fig 2: Identifying Pump Housing-To-Rotor Axial Clearance
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check the pump housing-to-outer rotor radial clearance between the outer rotor (A) and pump housing (B). If the pump housing-to-outer rotor radial clearance exceeds the service limit, replace the oil pump assembly.
Pump Housing-to-Outer Rotor Radial Clearance

Standard (New): 0.10-0.19 mm (0.004-0.007 in.)

Service Limit: 0.20 mm (0.008 in.)

Fig 3: Identifying Pump Housing-To-Outer Rotor Radial Clearance
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Inspect both rotors and the pump housing for scoring or other damage. Replace the parts, if necessary.
Apply liquid thread lock to the pump housing screws, then install the oil pump cover.
Check that the oil pump turns freely.