Here's a general overview. Specifics might vary slightly depending on your exact engine (4.6L or 5.4L V8). Always consult a repair manual specific to your vehicle's year, make, model, and engine for detailed instructions and diagrams. A Haynes or Chilton manual is a good investment.
Tools You'll Likely Need:
* Wrench(es): The size will depend on your vehicle; you'll need wrenches to access and potentially loosen the belt tensioner. Consult your repair manual.
* Socket wrench set: Useful for various bolts.
* Jack and jack stands: Essential for safety – never work under a vehicle supported only by a jack.
* Wheel chocks: To prevent the vehicle from rolling.
* New accessory drive belt: Make sure you get the correct belt size for your vehicle. The size is usually printed on the old belt, or you can find it in a parts catalog or online.
* Gloves: To protect your hands.
* Safety glasses: To protect your eyes.
* A ratchet and extensions: Can greatly simplify the process.
* Pry bar (optional): Might be needed to assist in belt removal in some cases.
General Steps (Consult your repair manual for precise details):
1. Safety First: Park on a level surface, engage the parking brake, and use wheel chocks. Raise the vehicle using a jack and secure it safely on jack stands.
2. Locate the Belt Tensioner: This is usually a pulley with a mechanism to adjust belt tension. It's often located near the alternator or power steering pump.
3. Loosen the Tensioner: This is the crucial step. Use the appropriate wrench(es) to loosen the tensioner. This will allow you to remove the belt. Some tensioners require turning a bolt or using a special tool; your repair manual will show you how. Be careful, as the tensioner will spring back when released.
4. Remove the Old Belt: Once the tension is released, carefully slip the old belt off the pulleys.
5. Install the New Belt: Route the new belt around the pulleys in the same order as the old belt. Make sure it's properly seated on all pulleys.
6. Tighten the Tensioner: Carefully tighten the tensioner back to its proper position. This requires feeling – you want enough tension so the belt doesn't slip, but not so much that you strain components. Your repair manual may indicate a specific method or measurement.
7. Check Belt Tension: After tightening, visually inspect the belt. It should be snug but not overly tight. You may be able to gently push on the belt mid-span. There should be some slight give, but it should not be excessively loose.
8. Lower the Vehicle: Carefully lower the vehicle from the jack stands.
9. Start the Engine: Run the engine for a few minutes to check for any squeaks or squeals, which could indicate improper tension or routing.
Important Considerations:
* Belt Routing: Pay close attention to the belt routing. Incorrect routing will cause problems.
* Tension: Improper tension is the most common mistake. If the belt is too loose, it will slip and squeal. If it's too tight, it can put excessive strain on bearings and pulleys, leading to premature wear.
* Pulley Condition: While you're at it, inspect the pulleys for wear or damage.
Again, I strongly recommend using a repair manual specific to your 1999 Ford Expedition XLT. This guide is for general information only and should not be considered a substitute for professional advice or a proper repair manual. If you are not comfortable performing this task, take your vehicle to a qualified mechanic.
