Obvious Signs:
* White smoke from the exhaust: This is a classic symptom. The white smoke is usually caused by coolant leaking into the combustion chamber and turning into steam. Pay close attention to the color; blueish-white often indicates burning oil as well, suggesting further problems.
* Overheating: The engine may overheat frequently, especially under load. This happens because the coolant is leaking, reducing its ability to cool the engine. The temperature gauge will climb rapidly.
* Coolant loss: You'll notice a decrease in coolant level in the radiator or overflow tank without any visible leaks. The coolant may disappear mysteriously.
Less Obvious Signs (requiring more investigation):
* Oil contamination: The oil may become milky or have a mayonnaise-like consistency. This indicates coolant mixing with the oil. Check your dipstick regularly.
* Coolant contamination: The coolant may show signs of oil contamination (oily sheen or discoloration).
* Compression loss: A compression test can reveal low compression in one or more cylinders, indicating a leak past a blown head gasket. This is a more definitive test performed by a mechanic.
* External coolant leaks: While not always directly related to a *blown* head gasket, significant coolant leaks *around* the head gasket area are a strong indicator of a problem that might lead to a blown head gasket if left untreated.
* Engine misfires: The engine may misfire due to combustion problems caused by coolant entering the cylinders.
* Sweet smell from the exhaust: Coolant has a sweet smell, and this may be noticeable in the exhaust if it's leaking into the combustion chamber.
Important Note: Some of these symptoms can be caused by other problems, such as a cracked cylinder head, warped head, or failing thermostat. A proper diagnosis requires a thorough inspection by a qualified mechanic. Don't attempt extensive repairs yourself unless you have significant mechanical experience. Ignoring a blown head gasket can lead to severe engine damage.
