Here's a general outline of the process. Specific steps and torque specifications will vary slightly depending on whether you have a rear differential only, or a front and rear differential (depending on the drivetrain: 4x2, 4x4 Quadra-Drive I, Quadra-Drive II, etc.). Always consult your vehicle's repair manual for exact procedures and torque specifications.
Tools You'll Likely Need:
* Jack and jack stands (crucial for safety!)
* Wheel chocks
* Wrench(es) to remove drain and fill plugs (sizes vary)
* Socket set with extensions and ratchet
* Torque wrench (essential for proper tightening)
* Drain pan
* Funnel
* New differential fluid (correct type and quantity - check your owner's manual)
* Gloves
* Shop rags or paper towels
Steps:
1. Safety First: Park the Jeep on a level surface, engage the parking brake, and use wheel chocks. Raise the vehicle using a jack and securely support it on jack stands. Never work under a vehicle supported only by a jack.
2. Locate Differentials: Identify the differential(s). The rear differential is usually located near the rear axle. If you have a 4x4, the front differential will be near the front axle.
3. Drain the Fluid: Locate the drain plug on the bottom of the differential. Place your drain pan underneath. Carefully loosen and remove the drain plug, letting the old fluid drain completely. This can take a while.
4. Remove the Fill Plug (Important!): Before you put in new fluid, locate and remove the fill plug. This is important because if you can't remove it easily, you may have a problem that needs attention before proceeding. If it's difficult to remove, apply penetrating oil and try again. Don't force it. A seized fill plug means the differential likely needs more serious attention.
5. Replace the Drain Plug: Once the fluid has completely drained, replace the drain plug and tighten it to the manufacturer's specified torque (found in your repair manual). Do not overtighten.
6. Add New Fluid: Using a funnel, add the correct type and amount of differential fluid. Refer to your owner's manual for the specifications. You'll want to add it until it starts to trickle out of the fill hole.
7. Replace the Fill Plug: Once the fluid level is correct, replace the fill plug and tighten it to the manufacturer's specified torque.
8. Lower the Vehicle: Carefully lower the vehicle using the jack.
9. Check for Leaks: Inspect the area around the drain and fill plugs for any leaks.
10. Dispose of Old Fluid: Dispose of the old differential fluid properly according to local regulations. It's usually considered hazardous waste.
Important Considerations:
* Fluid Type: Use the correct type of differential fluid specified in your Jeep Grand Cherokee's owner's manual. Using the wrong fluid can severely damage the differential. This will often be a specific weight of gear oil, perhaps a synthetic blend, and may even specify a limited-slip additive if your vehicle has a limited-slip differential.
* Torque Specifications: Always refer to your owner's manual for the correct torque specifications for the drain and fill plugs. Using a torque wrench is crucial to prevent damage.
* Frequency: Differential service intervals depend on your driving conditions and the type of fluid used. Check your owner's manual for recommendations, but generally, it's a good idea to service it every 30,000-60,000 miles or as needed.
Again, if you're not comfortable performing this service, take your Jeep to a qualified mechanic. Improper servicing can result in costly repairs.
