Obvious Signs (requiring immediate attention – don't drive the car):
* Loud Knocking or Rod Knock: A rhythmic knocking sound, especially noticeable when accelerating, is a classic sign of a connecting rod failing. This is a catastrophic engine failure.
* Loss of Compression: This is difficult to diagnose without a compression test, but it can manifest as a significant loss of power, difficulty starting, or backfiring.
* White Smoke from Exhaust: Thick, white smoke indicates coolant is leaking into the combustion chamber, a serious internal engine failure. Blue smoke indicates oil burning, another bad sign, though not necessarily a complete "blown" engine.
* Visible Damage: If you see any visible damage to the engine block (cracks, broken parts), it's definitely blown. This could be external damage from an accident, or internal parts pushing through the block.
* Overheating: While overheating can have other causes, extreme and persistent overheating can lead to engine damage and could be a symptom of a larger internal problem.
* Metal shavings in the oil: If you check your oil and see metal shavings, this is a very bad sign of internal engine damage.
Less Obvious Signs (warrant further investigation):
* Loss of Power: A sudden or gradual decrease in engine power is a warning sign.
* Rough Running/Misfiring: The engine may run roughly, hesitate, or misfire, potentially accompanied by a check engine light.
* Burning Oil Smell: A strong burning oil smell indicates oil is leaking somewhere and possibly burning in the engine.
* Unusual Noises: Any new or unusual noises coming from the engine, such as grinding, whining, or squealing, warrant immediate attention.
* Leaking Fluids: Check for leaks – oil, coolant, or transmission fluid. While not always indicative of a completely blown engine, it could signal underlying problems leading to a failure.
Important Note: If you suspect your engine is blown, do *not* continue to drive it. Driving a severely damaged engine can cause further damage and potentially lead to a more costly repair. Have it towed to a mechanic for diagnosis and repair. Ignoring the signs can result in irreversible engine damage.
