Oil Pump Overhaul: Inspection

Remove the screws from the pump housing, then separate the housing and 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: Checking Inner-To-Outer Rotor Radial Clearance Between Inner Rotor And Outer Rotor
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check the housing-to-rotor axial clearance between the rotors (A) and pump housing (B). If the housing-to-rotor axial clearance exceeds the service limit, replace the oil pump assembly.
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: Checking Housing-To-Rotor Axial Clearance Between Rotors And Pump Housing
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check the housing-to-outer rotor radial clearance between the outer rotor (A) and pump housing (B). If the housing-to-outer rotor radial clearance exceeds the service limit, replace the oil pump assembly.
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: Checking Housing-To-Outer Rotor Radial Clearance Between Outer Rotor And Pump Housing
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Inspect both rotors and 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.