Safety First:
* Let the engine cool completely before starting any work. Hot coolant can cause serious burns.
* Wear safety glasses to protect your eyes from splashes.
* Work in a well-ventilated area. Coolant is toxic.
* Have appropriate containers to collect the used coolant. Dispose of it properly according to your local regulations (it's usually not allowed down the drain).
* Have gloves to protect your hands from the coolant and grime.
Tools and Materials:
* Large drain pan: To collect the old coolant.
* Wrench(es): Appropriate size for your radiator drain petcock (usually a 1/2" or 9/16" wrench) and for the coolant reservoir cap.
* Garden hose: With a spray nozzle.
* Clean buckets: Several, for flushing and collecting the used fluid.
* Radiator flush solution: Available at most auto parts stores. Follow the instructions on the bottle. (Some prefer using a mixture of water and white vinegar as an alternative, but a dedicated flush is typically more effective.)
* New coolant: The correct type for your Grand Prix (check your owner's manual). Pre-mixed 50/50 coolant is usually recommended.
* Funnel: To refill the radiator.
Steps:
1. Locate the radiator drain petcock: This is usually located at the bottom of the radiator, on the driver's side.
2. Place the drain pan under the petcock.
3. Carefully open the radiator cap (again, ensure the engine is completely cold!). Some pressure may remain even after cooling. Loosen slowly to relieve pressure gradually.
4. Open the drain petcock: Let the old coolant drain completely into the pan.
5. Once drained, close the petcock.
6. Remove the lower radiator hose (the hose connecting the radiator to the engine block). This will allow for more thorough flushing. You may need pliers or a hose clamp tool. Have a bucket ready to catch remaining coolant.
7. Connect a garden hose to the upper radiator hose connection (the hose connected to the engine). Turn the water on slowly, aiming the spray toward the lower radiator hose opening. Let water flow through the system for several minutes to flush out as much of the old coolant and gunk as possible. You might want to reverse the flow too (if possible by using the hose in both hose connections), so gunk dislodges from the engine block.
8. Repeat step 7 with a radiator flush solution, following the product's instructions on mixing ratios and dwell time. Let the solution sit in the radiator for the recommended time.
9. Reconnect the lower radiator hose.
10. Add the new coolant through the radiator's filler neck (or the coolant reservoir, depending on your system). Use a funnel to avoid spills. Fill the system to the proper level (check your owner's manual).
11. Run the engine for about 15-20 minutes, with the radiator cap off initially (monitoring the coolant level and for leaks) then replace the cap when it starts to reach normal operating temperature. This allows the thermostat to open and circulate the new coolant throughout the entire system.
12. Check for leaks and top off the coolant as needed. Monitor the coolant level for a few days to ensure there are no leaks.
Important Considerations:
* Rust: The brown gunk might indicate significant rust inside the radiator or engine block. If this is the case, a flush may only provide a temporary solution. A severely rusted system might require radiator replacement or more extensive repair.
* Blockage: Severe buildup could clog passages within the cooling system. A pressure test might be necessary to determine if there are any blockages.
* Coolant type: Use the correct coolant type specified in your owner's manual. Mixing different types can lead to problems.
This is a simplified guide. Always refer to your vehicle's repair manual for specific instructions and torque specifications. If you're not comfortable performing this task yourself, it's best to seek professional help. A botched radiator flush can cause significant engine damage.
