Chevrolet Silverado / GMC Sierra. Service manual — part 900

Fig. 204: Exploded View Of Oil Pump
Courtesy of GENERAL MOTORS CORP.

1. Remove the wear plate (1).

2. Note the presence or absence of punch marks on the drive gear and driven gear.

3. If not punch-marked, mark the gears so as to be able to reinstall them in their original

positions.

4. Remove the drive gear (2) and driven gear (3) from the oil pump body (4).

5. Remove the O-ring (6).

OIL PUMP INSPECTION

IMPORTANT: The oil pump drive gear and driven gear have a punch mark

on one side. Before the gears are removed from the oil pump,
the presence or absence of the punch marks on the gears
must be noted so that the gears can be reinstalled in the
original orientation.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Fig. 205: Measuring Depth Of Oil Pump Body Gear Cavity
Courtesy of GENERAL MOTORS CORP.

1. Measure the depth of the oil pump body gear cavity at dimension A.

Specification: The gear cavity maximum depth is 24.940 mm (0.9819 in).

IMPORTANT:

Make the following measurements described below at
several locations.

Replace the oil pump body, driven gear and drive gear if
any of the following specifications are not met.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Fig. 206: Measuring Inside Diameter Of Oil Pump Body Gear Cavity
Courtesy of GENERAL MOTORS CORP.

2. Measure the ID of the oil pump body gear cavity at dimension A.

Specification: The gear cavity maximum ID is 109.191 mm (4.2989 in).

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

Fig. 207: Measuring Outside Diameter Of Oil Pump Driver Gear
Courtesy of GENERAL MOTORS CORP.

3. Measure the OD of the driven gear at dimension A.

Specification: The driven gear minimum OD is 108.987 mm (4.2908 in).

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado