* Ticking or tapping: This is often the first sign. It's a high-pitched, rapid tapping sound that increases with engine speed. It's caused by insufficient lubrication leading to metal-on-metal contact in the engine. This is different from the normal valve train tick which is usually more consistent and not so speed-dependent.
* Knocking or rattling: A louder, more pronounced knocking or rattling sound indicates more serious damage. This happens when there's significant lack of lubrication, leading to parts hitting each other with force.
* Low oil pressure light: This is crucial. If your oil pressure light comes on, immediately turn off the engine. Continuing to run the engine with low oil pressure will cause catastrophic damage.
* Whining noise: Some oil pumps produce a whining sound when failing, particularly if the pump itself is worn or damaged internally. This sound is often consistent but can change pitch with engine speed.
* Complete engine seizure: In the worst-case scenario, the lack of lubrication will cause the engine to seize completely. This means the engine will lock up and refuse to turn. You'll likely hear a grinding, scraping, or metallic screeching sound *before* the seizure.
It's important to note that these sounds can sometimes be confused with other engine problems. If you suspect a bad oil pump, do not continue to run the engine. Immediate inspection by a qualified mechanic is crucial to prevent further, potentially irreversible, damage.
