Obvious Signs:
* Won't crank: This is the most prominent sign. When you turn the key, you'll hear nothing or just a clicking sound from the starter (indicating the starter is trying but can't overcome the resistance). The engine won't even try to turn over.
* Unusual resistance when trying to turn the engine by hand (if accessible): If you can access the crankshaft pulley (usually at the front of the engine), try turning it by hand with a wrench. A locked engine will be completely immobile. Caution: Be extremely careful doing this as you could injure yourself.
Less Obvious but Suggestive Signs (that may point towards a problem *leading* to a locked engine):
* Recent overheating: Overheating can cause catastrophic engine damage, including a seized engine.
* Loud knocking or other unusual engine noises before it stopped: This could indicate a serious internal problem that eventually led to the engine seizing.
* Loss of oil pressure: Lack of lubrication is a major cause of engine seizure. Check your oil level and look for leaks.
* Smoke from the engine compartment: While not always indicative of a locked engine, significant smoke can be a symptom of serious internal damage.
Things to *Rule Out* before concluding a locked engine:
* Dead battery: A weak or dead battery will prevent the engine from cranking. Test the battery voltage.
* Faulty starter motor: A bad starter won't engage the engine, even if the engine is fine. Attempt to jump start the vehicle. A clicking sound often indicates a starter problem, but it's not conclusive that the engine is seized.
* Broken timing belt: A broken timing belt will prevent the engine from turning, but usually, there will have been a preceding noise.
Important Note: If you suspect a locked engine, do not attempt to force it. This could cause further damage. Have it towed to a qualified mechanic for diagnosis and repair. Trying to crank a locked engine can severely damage the starter motor and potentially other components.
