This is a general overview; the exact steps may vary slightly depending on your specific engine (2.4L or 3.1L). Always consult a repair manual specific to your vehicle's year, make, model, and engine for detailed instructions and torque specifications. A Haynes or Chilton manual is a good investment.
Tools You'll Likely Need:
* Jack and jack stands: Essential for safe vehicle support.
* Wheel chocks: To prevent the car from rolling.
* Wrench set (metric): Various sizes, including sockets, ratchets, and extensions.
* Screwdrivers (Phillips and flathead): Various sizes.
* Pliers: Needle-nose and regular.
* Drain pan: To catch coolant.
* New water pump: Make sure you get the correct one for your engine.
* New coolant: Use the correct type specified in your owner's manual.
* New gasket(s): The water pump will likely come with a new gasket; you may need others depending on what needs to be removed.
* New thermostat (optional but recommended): Since you're already in there, replacing it is a good preventative measure.
* Torque wrench: Crucial for tightening bolts to the correct specifications to prevent leaks and damage.
* Flashlight: Helpful for working in tight spaces.
* Gloves: To protect your hands.
* Safety glasses: Protect your eyes from coolant and debris.
General Steps (Consult your repair manual for specifics):
1. Safety First: Disconnect the negative battery cable. Raise the vehicle securely using a jack and jack stands, and place wheel chocks on the wheels.
2. Drain the Coolant: Locate the drain plug on the engine block (usually near the bottom of the radiator). Place your drain pan underneath and carefully open the plug to drain the coolant.
3. Remove Drive Belts: Loosen and remove the serpentine belt (or individual belts if your engine uses multiple). You'll need a belt tensioner wrench or other appropriate tool for this.
4. Remove the Fan and Shroud (if necessary): This often needs to be done to access the water pump. You may need to remove some screws or bolts.
5. Remove Accessories as Needed: Depending on your engine, you may need to remove or loosen other components like pulleys or hoses to gain access to the water pump.
6. Remove the Water Pump: This usually involves removing several bolts securing the pump to the engine block. Take note of the bolt positions and order.
7. Install the New Water Pump: Carefully install the new water pump, ensuring the gasket is properly seated. Tighten the bolts to the manufacturer's specified torque.
8. Reinstall Components: Reinstall everything you removed in reverse order, ensuring everything is properly seated and connected.
9. Refill Coolant: Add new coolant to the radiator and the overflow tank, making sure to use the correct type and mix (usually a 50/50 mix of coolant and distilled water).
10. Bleed the Air from the Cooling System: This is crucial to prevent overheating. Run the engine until it reaches operating temperature, then let it cool down. Check the coolant level and add more if needed. Repeat the process until no more air is expelled from the system. Consult your repair manual for the proper bleeding procedure.
11. Test: After everything is reassembled, start the engine and check for leaks around the water pump and other connections. Monitor the temperature gauge to ensure the engine is not overheating.
Again, this is a simplified overview. Use a repair manual specific to your 1999 Pontiac Grand Am for precise instructions and torque specifications. Improper repair can lead to serious engine damage. If you are not comfortable performing this repair, take your vehicle to a qualified mechanic.
