NP273D Transfer Case Fluid Change Tips
You will need the following items to do the job:
- A 10mm hex driver socket or 10mm allen wrench.
- A large-diameter drain pan...one of those Wedco 5-gallon pans will work.
- Some rags.
- 3 quarts of ATF+4 (or your favorite t-case fluid).
- A suction gun.
There are only 2 plugs on the back of the transfer case: the lower one is for draining and the upper is for filling. Torque spec on them is 30-40 lb-ft. Fluid capacity is listed in the service manual as 4 pints (2 quarts).
Clean the area around the drain and fill plugs. Remove the drain plug. If you have the skid plate under the transfer case the fluid will exit the drain, flow onto the skid plate, and pour over the edges of the plate in 6-10 different places in a roughly 1-ft circle (hence the need for a large diameter drain pan). This is if you're on level ground. You can certainly catch it all, just be prepared for it!
Remove the fill plug and re-install the drain plug after all the old fluid has drained.
Using the suction gun, suck fluid out of one of the ATF+4 containers, then insert the gun tube into the fill hole and squeeze out the fluid. My suction gun takes in about 1 pint per suck. During this procedure it's important to bear in mind that the transfer case has no filtration and hence no ability to remove contaminants from the fluid (there is a magnet, but you have to crack open the case to get to it). That means you've got to be careful to keep the suction gun hose from contacting dirty underbody components on its way into the fill hole.
Re-install the fill plug.
Although the factory spec is 2 quarts, mine took just about 3 full quarts to fill to the bottom of the fill hole, so you should buy at least 3 quarts of whatever fluid you intend to use.