1. Do NOT drive the car: This is the most important step. Driving with low coolant will overheat the engine, potentially causing irreparable damage. Even a short trip can be harmful.
2. Check the coolant level: Carefully open the radiator cap (only when the engine is completely cool! Hot coolant under pressure can cause severe burns). Check the coolant level. If it's low, you need to find out why.
3. Look for leaks: Inspect the radiator, hoses, water pump, and engine block for any visible leaks. Look for wet spots, stains, or dripping coolant.
4. Possible causes (in order of likelihood):
* Leak in the cooling system: This is the most common cause. A leak can be anywhere from a small crack in a hose to a larger problem with the radiator or water pump.
* Head gasket failure: This is a much more serious problem, potentially involving internal engine damage. Symptoms often include white smoke from the exhaust, milky oil, and overheating.
* Coolant leak into the engine oil: This will cause your oil to become milky or look like chocolate milkshake. This is serious and requires immediate professional attention.
* Radiator fan malfunction: This can prevent adequate cooling. The fan should come on when the engine gets hot.
* Thermostat stuck closed: This will prevent coolant from circulating, causing the engine to overheat.
* Low coolant level due to evaporation or leakage: If there are no visible leaks, it might be due to slow leakage or evaporation.
5. What to do next:
* If you find a leak: You may be able to temporarily add coolant (make sure it's the correct type - check your owner's manual), but this is only a temporary fix. You MUST have the leak repaired by a mechanic as soon as possible.
* If you don't find a leak: This is more serious and needs professional diagnosis to pinpoint the cause (head gasket, thermostat, water pump etc.).
6. Call a tow truck or roadside assistance: Do not attempt to drive the car. Have it towed to a qualified mechanic for diagnosis and repair. Ignoring the problem will only lead to more extensive and expensive repairs.
Important Note: Never remove the radiator cap while the engine is hot or even warm. The pressure inside the system can cause severe burns. Always let the engine cool completely before attempting any checks or repairs.
