Reasons why it could be a head gasket or warped head:
* Overheating damage: If the car was severely overheating *before* the repairs, the heat could have already damaged the head gasket or warped the head. The new pump and thermostat only addressed the *symptoms*, not the underlying cause.
* Improper repair: If the water pump or thermostat wasn't installed correctly, it could lead to inadequate cooling, causing overheating and subsequent head gasket/head damage. Air pockets in the cooling system are a common culprit.
* Pre-existing issue: A crack in the block or head, or other cooling system problems (e.g., radiator issues, a blockage), might have existed before the pump and thermostat failure and exacerbated the overheating.
Other possibilities:
* Air in the cooling system: This is a VERY common cause of overheating after a water pump or thermostat replacement. The system needs to be properly bled (burped) to remove all air pockets.
* Faulty thermostat: While you replaced it, there's a small chance the new thermostat is defective.
* Radiator issues: A clogged radiator, leaking radiator, or faulty radiator cap can all prevent the system from cooling properly.
* Faulty water pump (again): Though less likely, it's possible the new water pump is also faulty.
* Fan clutch: The fan clutch might not be engaging properly, preventing adequate airflow through the radiator.
* Low coolant level: Even after a repair, a leak elsewhere in the system could lead to low coolant levels and overheating.
What to do next:
1. Check coolant level: Make sure the coolant level is correct and there are no obvious leaks.
2. Bleed the cooling system: This is crucial. Follow the instructions in your car's repair manual or consult a reliable online guide specific to your 1995 Chevy Corsica.
3. Inspect for leaks: Carefully look for any leaks around the water pump, thermostat, hoses, radiator, and head gasket. Look for signs of coolant residue.
4. Check the radiator: Make sure the radiator fins aren't clogged and there are no leaks.
5. Test the radiator cap: Ensure the radiator cap holds pressure correctly.
6. Check the fan clutch: See if the fan engages properly when the engine gets warm.
7. Pressure test the cooling system: This is best done by a mechanic. A pressure test will help pinpoint leaks that might not be immediately obvious.
8. Check for exhaust gas in the coolant or coolant in the oil: These are strong indicators of a blown head gasket.
If you've done the above and the car is still overheating, it's time to take it to a mechanic for a proper diagnosis. They have the tools and expertise to determine if the head gasket or head is damaged. Ignoring a serious overheating problem can cause irreversible engine damage.
