Before You Begin:
* Safety First: Disconnect the negative battery cable before starting any work. This prevents accidental short circuits.
* Gather Tools: You'll need basic hand tools, including wrenches (metric), sockets, a ratchet, possibly a breaker bar, pliers, and a battery charger (just in case). A jack and jack stands are crucial for safe working conditions. You might also need a pulley puller depending on how the alternator pulley is attached.
* Repair Manual: A Haynes or Chilton manual for your specific year and model is invaluable. It will provide detailed diagrams and torque specifications.
General Steps (May vary based on your engine):
1. Prepare the Vehicle: Park on a level surface, engage the parking brake, and chock the wheels. Raise the vehicle using a jack and securely support it with jack stands.
2. Access the Alternator: The alternator is usually located on the front of the engine, near the lower radiator hose. Access may vary depending on the engine and accessories. You might need to remove some components like the air intake system, belts, or other shrouds to get a clear view and access to the alternator.
3. Disconnect the Electrical Connections: Carefully disconnect the electrical connectors from the alternator. Note which wire goes where – take photos or make a diagram if necessary.
4. Remove the Belts: Remove the serpentine belt (or multiple belts if applicable) from the alternator pulley. You'll likely need a belt tensioner tool or need to loosen a tensioner bolt to slacken the belt sufficiently for removal.
5. Remove the Alternator: This is where the specifics of your engine matter. The alternator is usually held in place by several bolts. Locate these bolts and carefully remove them. You may need to use a breaker bar for stubborn bolts. The alternator might be somewhat heavy; have a helper if possible.
6. Install the New Alternator: Carefully install the new alternator in the reverse order of removal. Ensure it's properly seated and all mounting bolts are tightened to the manufacturer's specifications (consult your repair manual).
7. Reconnect the Electrical Connections: Attach the electrical connectors, ensuring they are securely fastened.
8. Reinstall the Belts: Reinstall the serpentine belt(s), ensuring proper routing around all pulleys.
9. Lower the Vehicle: Carefully lower the vehicle from the jack stands.
10. Reconnect the Battery Cable: Reconnect the negative battery cable.
11. Test the Alternator: Start the engine and check the alternator's output voltage using a multimeter. It should be around 13.5-14.5 volts. If the voltage is low, there might be a problem with the installation or the new alternator itself.
Important Considerations:
* Belt Routing: Pay close attention to the belt routing. Incorrect routing can damage the alternator and other components.
* Torque Specifications: Always tighten bolts to the manufacturer's specified torque values. Over-tightening can damage the alternator or other parts. Under-tightening can lead to loose connections and potential failure.
* Pulley Removal: Some alternators have pulleys that are difficult to remove without a specialized pulley puller.
This is a general overview. Again, I strongly urge you to consult a repair manual specific to your 1990 Buick LeSabre before attempting this repair. If you're not comfortable performing this repair yourself, take it to a qualified mechanic. Improper installation can lead to further damage or injury.
