* Faulty Radiator: The radiator might be clogged with debris, have a leak (internal or external), or simply be inefficient due to age or damage. A pressure test can reveal leaks. Inspect the fins for damage or blockage.
* Low Coolant Level: Even after replacement, you might have air pockets in the system or a slow leak somewhere else. Check the coolant level in the overflow reservoir and make sure it's within the specified range. Top off as needed and look for signs of leakage.
* Head Gasket Failure: A blown head gasket allows combustion gases to enter the cooling system, pressurizing it and causing overheating. This often results in white or milky-looking exhaust smoke and/or coolant in the oil. Testing for this usually requires a professional mechanic.
* Clogged Cooling System: Despite replacing components, there might be sludge, rust, or other debris clogging passages within the engine block, radiator, or hoses. A flush of the entire cooling system might be necessary.
* Faulty Radiator Fan or Fan Clutch: The fan might not be working properly, failing to draw enough air across the radiator to dissipate heat. Check the fan's operation both manually and automatically (if it has an automatic temperature switch).
* Incorrect Thermostat Installation: While unlikely if you replaced it, ensure the thermostat was installed correctly and is opening and closing at the correct temperature.
* Warped Cylinder Head or Cracked Block: These are more serious issues that often require professional diagnosis and repair. Overheating can cause these problems, but they can also cause overheating.
* Air Pockets in the System: After replacing components, there might be air trapped within the cooling system, preventing proper coolant circulation. Bleed the system properly according to your vehicle's specifications.
* Water Pump Issues (despite replacement): While you replaced it, there's a slim chance the new water pump is faulty. Though less likely, verify the pump is actually circulating coolant.
What to do next:
1. Check coolant level and look for leaks. Inspect all hoses, clamps, the radiator, and the water pump for any signs of leakage.
2. Bleed the cooling system. Make sure there are no air pockets preventing proper circulation.
3. Pressure test the cooling system. This will pinpoint leaks that might be difficult to spot visually.
4. Check the radiator fan operation.
5. If you're not comfortable with these checks, take your vehicle to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately.
Overheating can lead to significant engine damage, so it's crucial to address this issue promptly.
