How to Change the Fluid on an Allison 2500 HD Transmission
- 1). Locate the drain plug of the transmission case. It will be underneath the vehicle, towards the center.
- 2). Place an oil pan underneath the drain plug, and unscrew the plug using an adjustable wrench. Allow the fluid five minutes to drain out.
- 3). Screw the drain plug back into the transmission oil pan.
- 4). Remove the bolts around the drain pan using a socket wrench with a socket wrench extension.
- 5). Pull out the drain pan slowly, being careful not spill fluid. This will expose the transmission fluid filter.
- 6). Remove the two bolts that hold the transmission fluid filter in place with a socket wrench and extension.
- 7). Place the new filter in its place and bolt it in using a socket wrench and extension.
- 8). Bolt the drain pan back into place.
- 9). Open the hood and remove the transmission fluid dipstick from the transmission fluid dipstick tube.
- 10
Place a funnel in the tube and refill the transmission with DEXTRON III automatic transmission fluid. Check the fluid level occasionally with the dipstick until the fluid reaches the fill line.
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