Here's a general procedure. Consult your owner's manual for specific details and torque specifications for your vehicle. Variations exist between engine types (4.3L V6, etc.).
Tools and Materials You'll Need:
* Drain pan: Large enough to hold several gallons of coolant.
* Wrench(es): To remove drain plugs (radiator and engine block). Sizes will depend on your vehicle.
* Hose: A garden hose with a spray nozzle is ideal.
* Funnel: To refill the radiator.
* New coolant: The correct type and amount for your Astro (check your owner's manual). Use a 50/50 mix of coolant and distilled water, unless otherwise specified.
* Flush solution (optional but recommended): A radiator flush solution helps remove scale and deposits more effectively.
* Protective gloves and eyewear: Essential for handling coolant.
Steps:
1. Cool Down: Let the engine cool completely. This is crucial to prevent burns.
2. Drain the Radiator: Locate the radiator drain petcock (usually at the bottom of the radiator). Place your drain pan underneath and carefully open the petcock to drain the coolant.
3. Drain the Engine Block: Many vehicles have a drain plug on the engine block as well. Locate this and drain the coolant from the engine block into the drain pan. This is important to remove coolant from the entire system.
4. (Optional) Flush with Water: Once drained, use your garden hose to flush the radiator. Connect the hose to the upper radiator hose inlet and let water flow through the radiator and out the drain petcock. You might need to remove the lower radiator hose for a more thorough flush. Repeat this process several times until the water runs clear.
5. (Optional) Use Radiator Flush Solution: Follow the instructions on the radiator flush solution you chose. This usually involves adding the solution to the radiator, running the engine for a short period, then draining again.
6. Refill the System: Close the drain petcocks. Add the 50/50 mix of coolant and distilled water to the radiator until it's full (check your owner's manual for the correct capacity).
7. Bleed the Air: Start the engine and let it run for a few minutes. Check the radiator and the coolant overflow reservoir. Squeeze the upper radiator hose to help release any trapped air. Add more coolant as needed. The air bleeding process can take some time; run the engine, check, add coolant, and repeat until the system is full and no more air bubbles are visible.
8. Check Coolant Level: After the engine has cooled, check the coolant level in the radiator and the overflow tank. Top off as necessary.
Important Considerations:
* Type of Coolant: Use the correct type of coolant specified in your owner's manual (typically Dex-Cool for GM vehicles of this era). Mixing different types of coolant can cause problems.
* Disposal: Coolant is hazardous waste. Dispose of it properly according to your local regulations. Many auto parts stores will accept used coolant for recycling.
* Professional Help: If you are uncomfortable performing this task yourself, take your Astro to a qualified mechanic.
This is a general guide. Variations exist between models. Always refer to your owner's manual for specific instructions and torque specifications. Improperly flushing your radiator can damage your engine, so proceed with caution.
