* Serpentine Belt: This is the most common cause of squealing in cars. A worn, cracked, or loose serpentine belt will squeal, particularly when cold or under stress (like idle when the alternator is working hard). Check the belt for cracks, fraying, or glazing. You should also check the tensioner pulley; if it's worn or seized, it can cause the belt to squeal.
* Alternator: A failing alternator bearing can also produce a high-pitched squeal, especially when the alternator is working hard (like at idle, charging the battery).
* Power Steering Pump: A problem with the power steering pump, such as a worn bearing or low fluid, can cause a squeal, often more noticeable when turning the steering wheel. Check the power steering fluid level.
* Water Pump: While less common to squeal at idle, a failing water pump bearing can make a noise. However, this is usually accompanied by other symptoms, like overheating.
* Idler Pulley: Similar to the tensioner pulley, a worn or damaged idler pulley can also cause a squeal.
Troubleshooting Steps:
1. Visual Inspection: Open the hood and carefully inspect the serpentine belt and all pulleys (alternator, power steering pump, idler, tensioner) on the left side of the engine. Look for cracks, fraying, or any obvious damage.
2. Listen Carefully: While the engine is running (with someone else present for safety), try to pinpoint the exact location of the squeal. This will help narrow down the source.
3. Check Fluid Levels: Check the power steering fluid level. Low fluid can cause squealing in the power steering pump.
4. Belt Tension: If the belt seems loose, it might be the cause. However, attempting to adjust belt tension requires some mechanical knowledge; if unsure, seek professional help.
Important Note: If you're not comfortable working on your car, take it to a qualified mechanic for diagnosis and repair. Ignoring a squealing sound can lead to more serious damage and potentially dangerous situations. A failing alternator, for instance, could leave you stranded.
