Here's a breakdown of potential leak sources and how to approach them:
1. Identify the Leak Source:
* Clean the area thoroughly: Use a degreaser and a wire brush to remove all dirt and grime around the rear axle. This will allow you to pinpoint the exact location of the leak.
* Inspect seals: Look closely at the axle seals (both inner and outer) for cracks, damage, or wear. These are common culprits. The pinion seal (where the driveshaft meets the differential) is another frequent source.
* Inspect axle tubes: Check for cracks or damage to the axle tubes themselves.
* Inspect differential cover: Examine the differential cover gasket for leaks.
* Check fluid level: Check the differential fluid level. Low fluid can indicate a leak but doesn't pinpoint the source.
2. Possible Leak Locations & Repairs:
* Axle Seals (Inner & Outer): Replacing axle seals requires specialized tools like a seal installer and remover to avoid damaging the axle housing or seals. This is a moderately difficult repair.
* Pinion Seal: Replacing the pinion seal is more challenging and often requires special tools and experience with differential disassembly. Incorrect installation can cause significant damage.
* Differential Cover Gasket: This is the easiest repair. It involves removing the cover, cleaning the mating surfaces, applying a new gasket, and reinstalling the cover with the correct torque.
* Axle Tube Leak: This is the most serious and requires welding or replacing the axle tube, a complex and expensive repair. Often, the axle assembly needs replacement.
3. Repair Steps (General Outline – Consult a Repair Manual):
1. Jack up the vehicle and secure it safely on jack stands. Never work under a vehicle supported only by a jack.
2. Remove the wheel and tire.
3. Access the leak location: This might involve removing brake components, driveshafts, or other parts. A repair manual will provide specific instructions.
4. Replace the damaged component: This may involve replacing seals, gaskets, or even larger components. Use new, high-quality parts.
5. Reassemble everything, ensuring proper torque on all bolts and nuts. Consult a repair manual for torque specifications.
6. Re-fill the differential with the correct type and amount of gear oil.
7. Lower the vehicle.
8. Check for leaks after driving for a short distance.
Important Considerations:
* Repair Manual: A factory service manual for your 2001 Ford Expedition is essential. It provides detailed instructions, torque specifications, and diagrams.
* Safety: Work in a well-ventilated area. Use safety glasses and gloves.
* Tools: You'll need a variety of tools including sockets, wrenches, a torque wrench, seal installer/remover, and possibly a differential carrier bearing puller depending on the leak source.
* Professional Help: If you are not comfortable working on your vehicle's drivetrain, it's best to take it to a qualified mechanic. Improper repairs can lead to serious and expensive damage.
This information is for guidance only. Always consult a repair manual specific to your vehicle for detailed instructions and safety precautions. Improper repair can lead to further damage and potential injury.
