Here's a general procedure. Always consult your vehicle's repair manual for specific details and torque specifications. This procedure is for informational purposes only and doesn't replace professional advice or a repair manual.
Tools You'll Need:
* Drain pan: Large enough to hold at least 4 quarts of fluid.
* Wrench: The correct size for your differential drain plug (likely 10mm, 12mm, or 14mm – check your manual).
* Fill plug wrench: Likely the same size as the drain plug, or possibly a different size depending on its type.
* New differential fluid: The correct type and amount (check your owner's manual). Commonly 75W-140 or 75W-90.
* Funnel: To avoid spills when refilling.
* Jack and jack stands: To safely lift and support the vehicle.
* Wheel chocks: For added safety.
* Rags or shop towels: For cleaning up spills.
Procedure:
1. Safety First: Park the Suburban on a level surface, engage the parking brake firmly, and chock the front wheels. Use jack stands to securely lift the rear of the vehicle. Never work under a vehicle supported only by a jack.
2. Locate the Drain Plug: The drain plug is usually located on the bottom of the differential housing. It might be a slightly recessed bolt or a plug with a square or hex head.
3. Remove the Drain Plug: Position your drain pan underneath the drain plug. Carefully loosen and remove the drain plug with the appropriate wrench. The fluid will start to flow out immediately, so be prepared.
4. Drain Completely: Allow the fluid to drain completely. This can take 15-20 minutes or longer. Inspect the drained fluid for unusual color, debris, or metallic particles which may indicate a problem.
5. Clean the Drain Plug: Clean any debris from the drain plug and the surrounding area. Replace the drain plug, tightening it to the manufacturer's specified torque (found in your repair manual). Do not overtighten.
6. Locate the Fill Plug: The fill plug is usually located on the top or side of the differential housing. It might be a different size from the drain plug.
7. Remove the Fill Plug: Loosen and remove the fill plug. This allows you to check the fluid level during refilling.
8. Refill the Differential: Using a funnel, carefully pour in the correct amount of new differential fluid. Refer to your owner's manual for the correct capacity. It's better to slightly underfill initially than overfill.
9. Check the Fluid Level: Once you've added most of the fluid, replace the fill plug and then check the fluid level. Ideally, the fluid should come out of the fill hole when you take the plug out, so don't fill beyond that.
10. Tighten the Fill Plug: Tighten the fill plug to the manufacturer's specified torque.
11. Lower the Vehicle: Carefully lower the vehicle using the jack.
12. Check for Leaks: Inspect the area around the drain and fill plugs for any leaks.
13. Dispose of Used Fluid Properly: Take the used differential fluid to a recycling center or auto parts store that accepts used oil for proper disposal.
Important Notes:
* Fluid Type: Using the incorrect fluid can severely damage your differential. Consult your owner's manual for the recommended fluid type.
* Torque Specifications: Always use a torque wrench and tighten the drain and fill plugs to the manufacturer's specified torque. Overtightening can strip the threads.
* Professional Help: If you're uncomfortable performing this task yourself, it's best to take your Suburban to a qualified mechanic.
This is a general guide. Always consult your vehicle's repair manual for specific instructions and torque specifications related to your 1999 Suburban. Incorrect procedures can lead to damage to your vehicle.
