Here's a general outline of the process. Specific steps and torque specifications may vary slightly depending on your exact rear axle configuration (e.g., 8.5-inch, 10-bolt, etc.). Always consult a repair manual specific to your truck's year, make, and model for detailed instructions and torque values.
Tools You'll Need:
* Repair Manual: Absolutely essential!
* Jack and Jack Stands: Securely support the truck.
* Wheel Chocks: Safety first!
* Socket Set and Wrenches: Various sizes, including those for the pinion nut.
* Torque Wrench: Crucial for proper tightening.
* Pinion Nut Socket: Special socket to fit the pinion nut.
* Bearing Separator: To remove the pinion seal without damaging it. (A slide hammer may also be used, but it's much easier to damage the seal)
* Gear Oil: The correct type for your differential.
* New Pinion Seal: Get a genuine GM seal or a high-quality replacement.
* Clean Rags or Shop Towels: For cleaning.
* Penetrating Oil (like PB Blaster): To help loosen bolts.
* Magnetic Parts Tray: To keep track of small parts.
* Safety Glasses and Gloves: Protect yourself.
Procedure (General Steps - Refer to your repair manual for specifics):
1. Safety First: Park on a level surface, engage the parking brake, and chock the wheels.
2. Raise and Support the Truck: Safely lift the rear of the truck and secure it on jack stands.
3. Remove the Drive Shaft: Disconnect and remove the driveshaft from the differential.
4. Drain the Gear Oil: Drain the differential fluid completely.
5. Remove the Pinion Nut: This will likely require a breaker bar and significant effort. Use penetrating oil if needed. Important: Mark the nut and pinion yoke's relative position before removing, to ensure proper reassembly and prevent backlash issues.
6. Remove the Pinion Yoke: This might involve removing some retaining clips or bolts.
7. Remove the Old Pinion Seal: Use a seal puller or carefully pry it out with a screwdriver (carefully!), avoiding damage to the pinion shaft.
8. Clean the Pinion Shaft: Thoroughly clean the pinion shaft where the new seal will sit, removing any old seal material or debris.
9. Install the New Pinion Seal: Gently tap the new seal into place using a suitable socket or seal installer. Do not hammer directly on the seal.
10. Reinstall the Pinion Yoke: Reinstall the pinion yoke, ensuring it's properly seated.
11. Reinstall the Pinion Nut: Tighten the pinion nut to the torque specification listed in your repair manual. This is critical!
12. Set Pinion Bearing Preload (This is the most critical part, and the repair manual is paramount): This requires special tools and precise measurement. Improper preload can lead to premature bearing failure. If you lack experience, skip this section and take it to a mechanic.
13. Reinstall the Driveshaft: Reinstall the driveshaft.
14. Reinstall the Axle Housing Cover: If necessary.
15. Refill the Differential with Gear Oil: Use the correct type and amount of gear oil specified for your differential.
16. Lower the Truck: Carefully lower the truck from the jack stands.
17. Check for Leaks: Inspect for leaks around the pinion seal after a short test drive.
Again, this is a simplified overview. The actual process involves several critical steps requiring precision and the right tools, especially setting the pinion bearing preload. Consult a comprehensive repair manual for your specific vehicle and follow its instructions meticulously. Improperly performing this repair could seriously damage your rear axle. If you're not confident in your abilities, it's best to seek professional help.
