Before attempting to repair the transfer case or related components for any reason other than mechanical failure, the condition and probable causes should be identified. Transfer case failures are revealed by shifting difficulties such as excessive shifting effort, gear clash, or gear grinding. When any of these conditions occur, the following inspections should be made before disassembling the transfer case.
- Inspect the transfer case oil level for insufficient or incorrect oil. Refer to Oil Replacement .
- Inspect the transfer case mounts for wear or looseness. Refer to Transfer Case Mount Replacement Transfer Case Rear Mount.
- Inspect the gearshift control lever for distortion or excessive wear. Refer to Shift Lever Replacement - On Vehicle .
After performing the above inspections, refer to the following tables for diagnosis of transfer case noise and shifting difficulties under various conditions.
Checks | Probable Cause |
|---|---|
Transfer case oil level | Insufficient or improper lubricant |
Tires | Wear, under inflation or improper size |
Input gear bearing | Wear or damage |
Rear output shaft bearings | Wear or damage |
Checks | Cause |
|---|---|
Transfer case oil level | Insufficient or improper lubricant |
Reduction shift shaft | Binding in center or rear case |
Front drive shift shaft | Binding in center or rear case |
Front drive-shift fork spring, c-clip or shaft stop washer | Weakness, distortion or mispositioned |
Checks | Cause |
|---|---|
Front drive clutch sleeve | Excessive wear or damage |
Reduction clutch sleeve | Excessive wear or damage |
Drive sprocket clutching teeth | Excessive wear or damage |
Reduction clutch hub | Excessive wear or damage |
Checks | Cause |
|---|---|
Manual locking front hubs | Hub dials in FREE position |
Automatic locking front hubs | Excessive wear or damage |
Most transfer case oil leaks can be located without removing the transfer case from the vehicle. Methods most commonly used to locate leaks are the general method, the powder method and the dye and black light method.
The transfer case components are constructed of aluminum and separated into four pieces: the front case, the center case, the rear case and the gearshift lever case. If a leak exists between any of the transfer case components, the transfer case must be removed from the vehicle for repair.
General Method
- Verify that the leak is transfer case oil.
- Thoroughly clean the suspected leak area.
- Drive the vehicle for 24 km (15 miles) or until normal operating temperatures are reached.
- Park the vehicle over clean paper or cardboard.
- Turn the ignition switch to the OFF position and wait approximately 30 minutes.
- Inspect the paper for spots in relation to its position under the transfer case assembly.
- Make the necessary repairs.
Powder Method
- Thoroughly clean the suspected leak area with solvent.
- Apply an aerosol powder or baby powder to the suspected leak area.
- Drive the vehicle for 24 km (15 miles) or until normal operating temperatures are reached.
- Turn the ignition switch to the OFF position.
- Inspect the suspected leak area and trace the leak path through the powder to find the source.
- Make the necessary repairs.
Tools Required
| • | J 28428-E High Intensity Black Light |
| • | J 28431-6 Fluorescent Oil Additive |
Dye and Black Light Method
- Raise the vehicle. Support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
- Add 30 ml (1 oz) of J 28431-6 into the transfer case oil level/filler plug.
- Lower the vehicle.
- Drive the vehicle for 24 km (15 miles) or until normal operating temperatures are reached.
- Turn the ignition switch to the OFF position.
- Raise the vehicle. Support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information
- Using J 28428-E , locate the source of the leak.
- Make the necessary repairs.
