Chevrolet Silverado / GMC Sierra. Manual - part 857
2. Remove the drain plug (7) and drain plug seal (6) from the oil pan (5). Allow the fluid to
drain into a suitable container.
3. Inspect the drained fluid. Refer to Transmission Fluid Check
4. Remove 12 bolts (8). Hold the oil pan in position as the last bolt is removed.
5. Remove oil pan (5) and gasket (3).
6. Inspect magnet (4). Excessive metallic particles or large metallic particles may indicate
need for overhaul or replacement of the transmission.
7. Remove the transmission internal oil filter (2) by pulling straight down where the suction
tube is seated in the transmission case.
8. Remove the transmission internal oil filter seal (1) from the filter or from the seal bore in
the transmission case. Discard the old seal. Discard the filter, if the filter is being replaced.
Installation Procedure
IMPORTANT: DO NOT remove the transmission internal oil filter or seal if
only replacing the oil pan or oil pan gasket.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Fig. 62: Drain Plug, Drain Plug Seal, Filter & Oil Pan
Courtesy of GENERAL MOTORS CORP.
1. Remove all gasket material from the transmission case. Remove any scratches from the
transmission case that would cause a split-line leak.
2. Place a new seal (1) on the tube of the transmission internal oil filter (2), if the filter was
removed. Be sure the seal locates against the shoulder on the internal oil filter tube.
3. Push the filter (2) and seal (1) into the seal bore in the transmission case. Position the
transmission internal oil filter properly.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
4. Install 2 headless guide bolts (9), M8 x 1.25, into opposite corners of the oil pan mounting
face on the transmission case.
5. Place a gasket (3) on the oil pan and align the bolt holes.
6. Slide the gasket (3) and oil pan (5) over the guide bolts and hold them in place while
installing 2 bolts (8) to hold the parts in place.
7. Remove the guide bolts.
8. Install the 10 remaining oil pan bolts (8).
Tighten: Tighten the bolts to 27 N.m (20 lb ft).
9. Install the drain plug (7) and drain plug seal (6).
Tighten: Tighten the drain plug to 35 N.m (26 lb ft).
10. Lower the vehicle.
11. Refill the transmission with DEXRON®VI Automatic Transmission Fluid. Refer to Fluid
Capacity Specifications .
12. Check the transmission fluid level. Refer to Transmission Fluid Check.
TRANSMISSION FLUID FILLER TUBE AND SEAL REPLACEMENT
Removal Procedure
NOTE:
Refer to Fastener Notice .
NOTE:
Refer to Component Fastener Tightening Notice .
NOTE:
Use only clean and approved transmission fluid.
IMPORTANT: Remember fluid remains in the external circuits and
transmission cavities after draining the transmission.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Fig. 63: Fill Tube Nuts
Courtesy of GENERAL MOTORS CORP.
1. The transmission case has provisions that enable the fill tube to be installed on either the
right or left side of the transmission. Proceed to step 9 if servicing the plug and/or seal
opposite the fill tube.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Automatic Transmission - Allison - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado