GM 25182606
Oil Pump

The inspection of the oil pump begins with body clearance measurement using a feeler gage when the driven gear is pushed to one side of the body. Replacement of the oil pump body sub-assembly is needed when the clearance exceeds 0.17 mm (0.0067 inch). The tip clearance between driven gear teeth and drive gear teeth must be measured with usual values between 0.07 - 0.15 mm (0.0028 - 0.0059 inch) and a maximum value of 0.15 mm (0.0059 inch). A replacement of the oil pump body sub-assembly becomes necessary if maximum values are exceeded. The measurement of gear side clearance requires a steel straight edge with a feeler gage that must be applied across both gears to check the standard 0.02 - 0.05 mm (0.0008 - 0.002 inch) clearance and the maximum limit of 0.05 mm (0.002 inch) which may require replacements of the drive gear or either gear and the pump body if exceeded. A dial indicator should measure the inner diameter of the oil pump body bushing to check if it exceeds standard 38.126 mm (1.50102 inch) or maximum 38.188 mm (1.50346 inch) which requires replacing the oil pump body sub-assembly. A dial indicator should be used to measure stator shaft bushing inside diameters to determine if the device requires replacement when the readings exceed 18.5 mm (0.728 inch) from the 18.437 mm (0.72586 inch) standard.

When maintaining the fluid pump, be very careful when handling oil seals as only slight damage to the lip of a seal may cause leakage of oil. First, rotate the drive gear using 2 screwdrivers so that it spins smoothly without letting the driver fall because it may get detached from the stator shaft. Then, take out the 8 bolts and the stator shaft, and then Oil Pump drive gear and oil shaft from Oil Pump body.

Exercise caution regarding fasteners as specified in the Fastener Notice under Service Precautions.