Tools you'll need:
* Drain pan: Large enough to hold several quarts of coolant.
* Wrench: To loosen the radiator drain petcock (if equipped; some models use a hose clamp). The size will depend on your specific model – check your owner's manual.
* Funnel: To pour coolant back into the radiator.
* New coolant: Use the correct type and amount specified in your owner's manual (usually a 50/50 mix of coolant and distilled water).
* Gloves: To protect your hands from the coolant.
* Shop rags or paper towels: For cleanup.
* Optional: Radiator pressure tester: Helps to identify leaks and ensure proper system pressure.
Steps:
1. Locate the radiator drain petcock: This is usually located at the bottom of the radiator, on the driver's side. It's a small valve. If you don't have a petcock, you might have a hose clamp on a lower radiator hose; loosen the clamp to drain.
2. Place the drain pan under the drain petcock/hose: Position it to catch all the coolant.
3. Open the drain petcock/hose clamp: Slowly open the petcock or loosen the clamp to allow the coolant to drain into the pan. Be careful, as the coolant will be hot if the engine was recently running.
4. Allow the radiator to drain completely: This may take some time.
5. Close the drain petcock/hose clamp: Once the coolant has stopped draining, tighten the petcock or re-clamp the hose.
6. Remove the radiator cap: Carefully remove the radiator cap. Some pressure might still be present, so do this slowly to avoid a spurt of coolant.
7. Fill the radiator with coolant: Using a funnel, add the correct type and amount of coolant (usually a 50/50 mix of coolant and distilled water) as specified in your owner's manual. Fill it to the designated "full" line or slightly below the neck.
8. Replace the radiator cap: Securely replace the radiator cap.
9. Start the engine and run it for a few minutes: This will allow the coolant to circulate through the system. Monitor the temperature gauge to ensure it stays within the normal operating range.
10. Check the coolant level: After the engine has cooled, check the coolant level in the radiator and add more if necessary. You may also have an overflow reservoir; check and fill that as needed according to your owner's manual.
11. Inspect for leaks: Check the area around the radiator and hoses for any leaks.
Important Considerations:
* Consult your owner's manual: This is the most important step. Your owner's manual will provide specific instructions and details for your 1991 Grand Prix model. The location of the drain petcock, the type of coolant to use, and the capacity of the cooling system will all be detailed there.
* Proper coolant mixture: Using the wrong coolant mixture or using tap water can damage your engine. Always use a 50/50 mix of coolant and distilled water.
* Safety first: Always let the engine cool completely before working on the cooling system. Coolant is toxic, so wear gloves and avoid skin contact.
* Professional help: If you are uncomfortable performing this task yourself, take your car to a qualified mechanic.
This guide provides general instructions. Always refer to your owner's manual for specific details relevant to your 1991 Pontiac Grand Prix.
