Oil Pump Visual Inspection and Measurement

Inspect the oil pump cover and the engine front cover for flatness.
Inspect the oil pump vanes, the oil pump vane rotor, the oil pump vane rings and the oil pump slide for localized flatting.
Inspect the oil pump slide pivot pin for firm seat.
Measure the oil pump axial clearances. Use a straight edge (1) and a feeler gauge.

Fig 1: Straight Edge Tool
Courtesy of GENERAL MOTORS COMPANY

NOTE: Oil pump components are installed.
1. The maximal axial clearance between engine front cover and oil pump vane rotor should be 0.1 mm (0.004 in).
2. The maximal axial clearance between engine front cover and oil pump vane should be 0.09 mm (0.0035 in).
3. The maximal axial clearance between engine front cover and oil pump vane ring should be 0.4 mm (0.016 in).
4. The maximal axial clearance between engine front cover and oil pump slide should be 0.08 mm (0.0031 in).
5. The maximal axial clearance between engine front cover and oil pump slide seal should be 0.09 mm (0.0035 in).
Measure the oil pump radial clearance. Use a feeler gauge (1). Measure the clearance between oil pump vane rotor and oil pump vane (3).

Fig 2: Feeler Gauge, Oil Pump Slide And Oil Pump Vane
Courtesy of GENERAL MOTORS COMPANY

The maximal clearance should be 0.05 mm (0.002 in).
Measure the clearance between oil pump vane and oil pump slide (2).
The maximal clearance should be 0.2 mm (0.008 in).