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Jeep Cherokee 1984-2001: How to Replace Transfer Case Fluid

Your transfer case is the heart of the Jeep's four wheel drive, but it's easy to overlook the regular servicing that keeps it healthy.

By Scott Phillips - September 16, 2015
Contributors: Admiral Off-Road

This article applies to the Jeep Cherokee XJ (1984-2001).

The two most common transfer cases on the Cherokee XJ are:

  • The NV231 Command Trac. This part-time 4WD system locks the front and rear differentials together. Shifting on-the-fly to 4 High and driving in 4 High is limited to loose or slippery surfaces. Shifting to 4 Low must be done under 5 mph. The NV231 Command Trac should not be driven on dry pavement in any 4WD selection, because the front and rear drive axles will bind.
  • The NV242 Selec Trac. This full-time 4WD system has an open center differential with a lockable, part-time 4WD selection. Shifting on-the-fly to 4 Full Time and driving in 4 Full Time can be done on dry pavement. Shifting on-the-fly to 4 Part Time is limited to loose or slippery surfaces. Shifting to 4 Low must be done under 5 mph. The NV242 Selec Trac should not be driven on dry pavement in 4 Part Time or 4 Low.

Reading the model number:

  • Depending on the manufacturer, your transfer case may be labeled NV for New Venture Gear, or NP for New Process Gear.
  • The first digit indicates the speed ranges. The number two indicates both High and Low range.
  • The second digit indicates strength. The Command Trac is three for medium duty and the Selec Trac is four for medium to heavy duty.
  • The third digit refers to the center differential. The Command Trac is one for a locking, part-time differential. The Selec Trac is two for an open, full-time differential with a lockable part-time feature.
Figure 1. Shifters and transfer cases.

Both transfer cases require approximately 1.2 liters of ATF, so two quarts will be plenty. Your manual may specify Dexron/Mercon 3 or Chrysler Group ATF+3 Type 7176. These are getting hard to find; however, Chrysler Service Bulletin 21-010-06 states that ATF+4 Type 9602 (Chrysler part 05013457AA) may replace all earlier ATFs. Use a bottle oil transfer pump to easily pump ATF up into the fill port. Replace damaged plugs with NAPA BK7041048 and Oil-Tite M22 crush washers. See Figure 2 for supplies needed.

Figure 2. Transfer case service supplies.

The recommended change interval is 30,000 miles. However, if you have driven through deep water, the fluid should be changed because water can be sucked into the transfer case through the breather port. See Figure 3 for a look inside the transfer case and its components.

Figure 3. Transfer case components.

Materials Needed

  • 2 quarts of automatic transmission fluid
  • 2 crush washers: 22mm internal diameter
  • 2 Hex plugs: NAPA BK7041048 (if needed)
  • 10mm Allen wrench or 30mm socket wrench
  • Breaker bar
  • Oil drain pan
  • Small hand pump
  • PB Blaster
  • Eye protection and mechanic's gloves
  • Floor jack and jack stands (if needed)

Step 1 – Lift the vehicle (if needed)

Your Cherokee may have enough ground clearance to work comfortably under it. However, if you need to raise the vehicle, use the lifting points from the Cherokee Service Manual shown in Figure 2. Place jack stands securely under the frame points as shown. Keep in mind that the vehicle must be level to accurately fill the transfer case, so work on a solid, level surface and don't lift the Cherokee from just one end.

Figure 4. Factory lift and support points.

Step 2 – Drain the transfer case

Your transfer case may have either 30mm Hex plugs or 10mm Allen plugs, and the plugs may be cold-welded tight. Use the breaker bar cautiously—don't round off the wrench flats. It is recommended to replace the troublesome Allen plugs with sturdier Hex plus, such as NAPA BK7041048. The NAPA plug has 22mm x 1.5mm thread with a 17mm shank.

  1. Spray the fill as well as drain plugs with PB Blaster and give it time to work.
  2. Remove the fill plug first. Use your finger and check that the old fluid level is near the fill port hole.
  3. Remove the drain plug and allow the fluid to drain into the drain pan.
  4. Install the drain plug with a new crush washer. Hand-tighten to contact and then add about 1/4 wrench turn to crush the sealing washer.
  5. Clean up the transfer case, so any leaks will be easy to spot.
Figure 5. Transfer case drain.

Pro Tip

Always open the fill port first. This allows you to verify that the old fluid level was correct, and ensures that you will be able to refill the transfer case before you drain it.

Step 3 – Fill the transfer case

  1. Screw the bottle pump into the ATF bottle and insert the nylon hose into the fill port.
  2. Pump the first quart fully in. You can watch your progress, if the bottle has a clear sight gauge on the side.
  3. Slow down on the second quart. It will only take a few ounces. Stop when ATF begins to run out of the fill port.
  4. Install the fill plug with a new crush washer. Hand-tighten to contact and then add about 1/4 wrench turn to crush the sealing washer.
  5. Clean up any drips.
Figure 6. Transfer case fill.

Pro Tip

Remember that the plugs are steel and the transfer case is aluminum. Avoid stripping the aluminum threads. Do not over-tighten!

Step 4 – Test drive and leak check

  1. Take the Cherokee for a drive and operate the transfer case selections to get the ATF warm.
  2. Check for leaks and tighten the plugs as needed.

Featured Video - Transfer Case Fluid Change

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