Safety First:
* Work in a well-ventilated area. Antifreeze is toxic.
* Wear gloves and eye protection.
* Let the engine cool completely before starting. Hot coolant can cause serious burns.
* Have a drain pan large enough to hold at least 10 quarts of coolant. You may need a larger one depending on the engine.
Tools and Materials:
* Drain pan
* Wrench(es) to fit the drain plug on the radiator and engine block (if applicable – some only drain from the radiator)
* New antifreeze (consult your owner's manual for the correct type and amount – typically 50/50 mix of antifreeze and distilled water)
* Distilled water
* Funnel
* Hose clamps (if replacing hoses – recommended as a preventative measure)
* New radiator hoses (optional, but recommended if old and brittle)
* Socket wrench and sockets (if you are replacing the thermostat or water pump)
* New thermostat (optional, but recommended)
* New water pump (optional, but recommended if leaking or showing signs of wear)
Procedure:
1. Locate the radiator drain petcock. This is usually a valve located at the bottom of the radiator.
2. Place the drain pan under the radiator.
3. Carefully open the radiator drain petcock and let the coolant drain completely. This may take some time.
4. Locate the engine block drain plug (if applicable). Some Astro vans have a drain plug on the engine block as well. If present, repeat steps 2 & 3 for this plug.
5. Once drained, close the drain petcock and engine block drain plug.
6. Remove the radiator cap. Be prepared for some pressure release (if the engine was recently run), so point the cap away from yourself.
7. Flush the cooling system (optional but recommended). After draining, fill the radiator with distilled water. Run the engine for about 10-15 minutes, then drain again. This helps remove old coolant and debris. Repeat this process once or twice if necessary.
8. Inspect the hoses. Check for cracks, bulges, or leaks. Replace any damaged hoses.
9. Fill the radiator with the pre-mixed 50/50 antifreeze and distilled water solution. Use a funnel to avoid spills. Refer to your owner's manual for the correct capacity.
10. Add coolant to the overflow tank (reservoir).
11. Start the engine and let it run for 10-15 minutes. Ensure the heater is turned on to allow the coolant to circulate through the entire system. Monitor the temperature gauge.
12. Check the coolant level. Add more coolant if necessary.
13. Allow the engine to cool completely. Check for leaks around the hoses, drain plugs, and radiator cap.
14. Check the coolant level again. Top off if needed.
Optional Maintenance:
* Thermostat Replacement: While you're at it, consider replacing the thermostat. A faulty thermostat can cause overheating.
* Water Pump Replacement: If you notice any leaks or suspect the water pump is failing, replace it. This is a more involved repair.
* Radiator Hose Replacement: Replacing hoses is a good preventative maintenance practice, especially if they are old and cracked.
Important Notes:
* Always double-check your owner's manual for specific instructions and torque specifications for your 1998 Chevy Astro.
* Dispose of the old antifreeze properly. Most auto parts stores will accept used antifreeze for recycling.
This guide offers general information. If you're uncomfortable performing this task, it's best to have a qualified mechanic do it. Improperly completed coolant changes can lead to engine damage.
