1. Cooling System Components:
* Water Pump: A failing water pump won't effectively circulate coolant, leading to overheating, especially at low speeds where there's less airflow over the radiator. Inspect the pump pulley for any play (wobble). A failing pump often makes a whining or groaning noise. Replacing the water pump is relatively straightforward but requires some mechanical aptitude.
* Radiator Fan: The radiator fan is crucial for low-speed cooling. Check if it's turning on when the engine reaches operating temperature. This usually involves a sensor and relay; a malfunctioning fan motor, relay, or temperature sensor can all prevent the fan from working. You can test the fan directly by applying power to the connector (be careful!), or using a multimeter to check the fan's motor resistance. A stuck fan clutch could also be the problem.
* Radiator Fins: Are the radiator fins bent or clogged with debris? Bent fins restrict airflow; debris (leaves, bugs, etc.) can significantly reduce the radiator's efficiency. Carefully straighten bent fins, and use a low-pressure air hose to clean out any debris.
* Head Gasket: A blown head gasket can allow coolant to leak into the engine's cylinders or the oil, causing overheating and potentially white smoke from the exhaust, milky oil, or a sweet smell in the exhaust. This is a serious issue requiring professional attention. A compression test or a leak-down test can help diagnose a head gasket problem.
* Coolant Leaks: Carefully inspect all hoses, clamps, and connections for leaks. Look for damp spots, corrosion, or signs of weeping coolant. Replace any damaged components.
2. Other Potential Issues:
* Low Coolant Level: Even after a flush, ensure the coolant level is correct. A small leak could gradually reduce the coolant level, leading to overheating.
* Blocked passages: Sometimes, even after a flush, there can be residual debris or mineral deposits blocking passages within the cooling system. A more thorough flush might be necessary, potentially with a chemical cleaner following manufacturer's instructions. This is a last resort.
* Sensor Issues: Incorrect readings from temperature sensors can cause the engine management system to respond incorrectly. A faulty coolant temperature sensor can lead to the cooling fan not turning on when needed. Have these sensors checked with a scanner.
Troubleshooting Steps:
1. Visual Inspection: Carefully inspect all components mentioned above. Look for obvious signs of damage, leaks, or debris.
2. Temperature Check: Monitor the engine temperature gauge closely, especially at low speeds. Note the conditions when the overheating occurs.
3. Fan Test: Check if the radiator fan is operating correctly at operating temperature.
4. Leak Test: Pressurize the cooling system with a tester to check for leaks.
5. Professional Diagnosis: If you're not comfortable performing these checks or if you suspect a serious problem like a head gasket, take your Contour to a qualified mechanic for diagnosis and repair.
Important Note: Overheating can cause serious engine damage. If the engine is overheating, don't continue to drive it. Let it cool down completely before attempting any repairs or further diagnostics.
