Here are the most likely culprits:
* Thermostat stuck closed: This is the most common cause. The thermostat regulates coolant flow. If it's stuck closed, coolant won't circulate through the radiator until it reaches a significantly higher temperature than normal.
* Water pump failure: The water pump is responsible for pushing coolant through the engine and radiator. A failing pump won't circulate coolant effectively.
* Clogged radiator: Internal blockage within the radiator itself can restrict coolant flow.
* Air in the cooling system: Air pockets can prevent proper circulation. This is often associated with a recent coolant flush or repair.
* Faulty radiator cap: A faulty cap might not allow sufficient pressure buildup, hindering proper coolant flow.
What to do:
1. Safety First: Let the engine cool completely before attempting any checks. The coolant will be extremely hot.
2. Check the thermostat: If you're comfortable working on your car, you can try to access and check the thermostat. You'll likely need to consult a repair manual for your specific vehicle. A failing thermostat often feels "stuck" when you try to move it.
3. Check the coolant level: Ensure the coolant reservoir is filled to the correct level. Low coolant can exacerbate circulation problems.
4. Feel the radiator: After the engine has been running, feel the radiator carefully (again, ensuring it's cool enough to touch safely). If the entire radiator is cool, the problem is almost certainly lack of circulation. If the top is hot and only the bottom is cool, it points to poor flow.
5. Check for leaks: Inspect hoses, clamps, and the radiator itself for any leaks.
If you're not comfortable performing these checks yourself, take your vehicle to a qualified mechanic. Ignoring this issue can lead to serious engine damage due to overheating.
