Here's a general outline of the process. Specific steps may vary slightly depending on the engine (3.4L or 3.8L) and whether you have additional accessories (like power steering). Always consult a repair manual specific to your 2004 Impala for detailed instructions and diagrams:
1. Preparation:
* Safety First: Disconnect the negative (-) battery cable. This is crucial to prevent electrical shocks and short circuits.
* Gather Tools: You'll need a socket wrench set (metric), ratchets, extensions, possibly a breaker bar, pliers, a wrench for the alternator's bolt (usually a 13mm or 15mm), and possibly a pulley tool if you need to remove the alternator pulley.
* Repair Manual: Obtain a repair manual specific to your 2004 Impala. This will provide diagrams and precise torque specifications for all bolts. This is essential to avoid damage.
2. Accessing the Alternator:
* The alternator's location varies slightly depending on the engine. Generally, it's located on the front of the engine, near the bottom, and often somewhat difficult to reach. You might need to remove other components to get sufficient access. Consult your repair manual for the exact location and any components that need to be removed (e.g., air intake components, belts, etc.).
3. Removing the Old Alternator:
* Disconnect Electrical Connections: Carefully disconnect the alternator's wiring harness connector(s) and the thick battery cable. Take pictures or make notes to remember how they are connected.
* Remove Bolts: Loosen and remove the bolts holding the alternator to the engine block. The number and location of these bolts will vary.
* Remove the Alternator: Carefully remove the alternator from its mounting bracket. It can be heavy.
4. Installing the New Alternator:
* Mounting: Carefully install the new alternator into its mounting bracket, ensuring it's properly seated.
* Secure with Bolts: Tighten the mounting bolts to the specifications in your repair manual. Over-tightening can strip the threads or damage the alternator.
* Reconnect Electrical Connections: Carefully reconnect the battery cable and wiring harness connector(s), matching them to how they were before.
* Reconnect the Negative Battery Cable: Reconnect the negative (-) battery cable.
5. Testing and Verification:
* Start the Engine: Start the engine and check the alternator's output voltage with a multimeter. It should be around 13.5-14.5 volts. If the voltage is low or not charging, there's a problem.
* Check for Leaks: Inspect for any fluid leaks around the alternator.
* Belt Tension: If you removed the serpentine belt, ensure it's properly tensioned and routed correctly.
Important Considerations:
* Serpentine Belt: You'll likely need to remove and reinstall the serpentine belt to access the alternator. Make sure you route it correctly after reinstallation.
* Pulley Removal: In some cases, you might need to remove the pulley from the alternator to facilitate the removal and installation process. This usually requires a special pulley puller tool.
* Torque Specifications: Always follow the torque specifications in your repair manual. Using incorrect torque can damage threads and components.
Again, this is a general guide. Always consult a repair manual for your specific 2004 Chevrolet Impala model and engine before attempting this repair. If you're uncomfortable with any part of this process, seek professional help from a qualified mechanic. Incorrect installation can lead to serious damage to your car's electrical system.
