Before you begin:
* Gather your supplies:
* Correct transfer case fluid (check your owner's manual; it's usually a synthetic ATF). The quantity needed varies, so purchase extra to be safe.
* New transfer case drain plug gasket (often a crush washer).
* New transfer case fill plug gasket (if applicable).
* Drain pan (large enough to hold the old fluid).
* Torque wrench
* 10mm, 13mm, and possibly other sockets depending on your truck (check your owner's manual).
* Ratchet and extensions
* Jack and jack stands (essential for safety)
* Wheel chocks
* Gloves
* Funnel
* Rags or shop towels
* Safety First: Work on a level surface, engage the parking brake, and use wheel chocks. The truck *must* be safely supported on jack stands, not just the jack.
Procedure:
1. Warm up the transfer case: Run the engine for 10-15 minutes to warm the fluid, making it flow more easily.
2. Position the vehicle: Securely jack up the truck and place it on jack stands. Make sure it's stable before proceeding.
3. Locate the drain and fill plugs: The location of these plugs varies slightly depending on the transfer case model. Consult a repair manual or online diagrams for your specific truck if you are unsure. The drain plug is usually lower than the fill plug. They're often 10mm or 13mm, but it’s best to verify.
4. Drain the fluid: Position your drain pan under the drain plug. Carefully remove the drain plug (it may be tight). Let the fluid drain completely. This can take a while. While draining, inspect the old fluid for metal particles or discoloration, which may indicate a problem.
5. Replace the drain plug gasket: Install a new crush washer on the drain plug before reinstalling it. Tighten it to the manufacturer's specified torque (consult your owner's manual).
6. Locate the fill plug: Again, location varies. Sometimes it's on the top or side, and may require a different size socket.
7. Fill the transfer case: Use a funnel to carefully pour in the correct amount of new transfer case fluid. You'll typically fill until fluid starts trickling out of the fill hole – this is often referred to as the "overflow" method. Be sure to consult your owner's manual for the exact capacity.
8. Replace the fill plug: Install the new fill plug gasket (if applicable) and tighten the fill plug to the manufacturer's specified torque.
9. Lower the vehicle: Carefully lower the truck from the jack stands.
10. Check the fluid level: After driving a short distance, recheck the fluid level. You may need to add a small amount more if the level is low.
Important Notes:
* Repair Manual: A repair manual specific to your 2004 Chevy Silverado 1500 4WD is highly recommended. It will have diagrams, torque specifications, and details specific to your truck's transfer case. Online resources like Haynes or Chilton offer these.
* Transfer Case Type: There are several types of transfer cases used in this model year. Knowing your specific type (e.g., NP241, NP246) will help you find the correct information and parts. This information is usually on a tag on the transfer case itself.
* Professional Help: If you're uncomfortable performing this task yourself, it's always best to take your vehicle to a qualified mechanic. Improperly servicing the transfer case can lead to serious damage.
This information is for guidance only. Always prioritize safety and refer to your owner's manual for precise instructions and specifications.
