Here's a general outline. Specific steps and tools may vary slightly depending on your Ranger's configuration (2WD vs. 4WD, specific axle type). Always consult a repair manual specific to your year and model for precise instructions and torque specifications.
Tools You'll Likely Need:
* Jack and jack stands: Crucial for safety. Never work under a vehicle supported only by a jack.
* Wheel chocks: To secure the vehicle.
* Lug wrench: To remove the wheels.
* Socket set and wrenches: Various sizes will be needed.
* Drain pan: For gear oil.
* Torque wrench: Essential for proper tightening.
* Pry bar: May be needed to help separate components.
* Hammer and punch: Possibly for installing the new seal.
* Seal installer (optional but recommended): Helps avoid damaging the new seal.
* Gear oil: The correct type and amount for your axle. Check your owner's manual.
* New rear axle seal: Get the correct seal for your axle.
* Shop rags or paper towels: For cleaning.
* Gloves: To protect your hands.
* Repair manual: Specific to your 1999 Ford Ranger.
General Steps (Consult your repair manual for precise details):
1. Safety First: Park on a level surface, engage the parking brake, and chock the wheels. Wear safety glasses.
2. Vehicle Preparation: Raise the rear of the truck securely using the jack and jack stands. Remove the wheel(s) on the affected side.
3. Drain the Axle Fluid: Locate the drain plug on the differential housing. Place the drain pan underneath and carefully remove the plug, allowing the gear oil to drain completely.
4. Remove the Axle Flange: This step varies depending on your axle type. You might need to remove brake components (calipers, rotors, etc.) to access the axle flange nuts. You'll need to remove the axle flange nuts and then separate the flange from the axle shaft. This may require some persuasion with a pry bar. Be careful not to damage the axle shaft.
5. Remove the Old Seal: Once the axle flange is removed, you should see the old seal. Use a pry bar (carefully!) or a seal puller to remove the old seal without damaging the axle housing. Clean the axle housing thoroughly.
6. Install the New Seal: Carefully install the new seal, ensuring it's seated properly and evenly. A seal installer tool is highly recommended to avoid damaging the new seal.
7. Reassemble: Carefully reassemble everything in reverse order, ensuring all bolts and nuts are tightened to the correct torque specifications (consult your repair manual). This includes reinstalling the axle flange, brake components, and the differential cover.
8. Refill with Gear Oil: Add the correct type and amount of gear oil to the differential housing (check your owner's manual).
9. Lower the Vehicle: Carefully lower the vehicle from the jack stands.
10. Check for Leaks: After driving a short distance, check for leaks around the axle seal.
Important Considerations:
* 4WD vs. 2WD: The procedure will be more complex for a 4WD Ranger due to the additional components.
* Axle Type: Different axles might require slightly different procedures.
* Torque Specifications: Following the correct torque specifications is crucial to prevent damage.
* Repair Manual: A repair manual specific to your 1999 Ford Ranger is absolutely essential.
This is a general overview. Refer to a repair manual specific to your 1999 Ford Ranger for detailed instructions and diagrams. Improperly replacing the seal can lead to further damage and costly repairs. If you're not comfortable with this task, it's best to take your Ranger to a qualified mechanic.
