* Normal cooling fan operation: Many cars have electric cooling fans that continue to run for a short time after the engine is shut off to cool down the radiator. This is perfectly normal. The duration of 10 seconds is within a reasonable range. Listen carefully to see if it sounds like a fan blowing.
* Power steering pump: Some power steering systems have a whirring noise as fluid is returned to the reservoir. This noise might linger briefly after the engine is off.
* Belt tensioner or pulley: A worn or failing belt tensioner or pulley can sometimes make a whirring sound. If the noise is metallic, this is more likely.
* Alternator: While less common, a failing alternator could produce a whirring noise that briefly continues after shutdown.
* Water pump (less likely): A very worn water pump *might* make a sound that lingers for a short time, but this is less probable than the other options.
To help determine the cause:
* Listen carefully: Try to pinpoint the location of the sound as precisely as possible.
* Check the fluid levels: Inspect your coolant, power steering fluid, and engine oil levels. Low fluid levels might indicate a leak and contribute to abnormal sounds.
* Check the belts: Look for any obvious cracks or fraying on the serpentine belt.
* Consider recent repairs: If you recently had any work done on your car, the noise might be related.
If the noise persists, is getting louder, or is accompanied by other symptoms (like overheating, loss of power steering, or a warning light), you should take your car to a mechanic for diagnosis. A short, infrequent whirring sound *might* be normal, but it's best to err on the side of caution and have it checked if you're concerned.
