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 the outer rotor (B) If the inner-to-outer rotor radial 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 Rotor Radial Clearance Between Inner Rotor And Outer Rotor
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check the pump housing-to-rotor axial clearance between the rotors (A) and the 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: Checking Pump Housing-To-Rotor Axial Clearance Between Rotors And Pump Housing
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Check the pump housing-to-outer rotor radial clearance between the outer rotor (A) and the 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: Checking Rotor Radial Clearance Between Outer Rotor And Pump Housing
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