1. Belt Tension:
* Double-check belt tension. Even a new belt can be too loose or too tight. The belt should have a slight deflection when pressed in the middle.
* Check the belt for wear and damage. Cracks, fraying, or glazing can cause slippage and squealing, even if the belt is new.
2. Accessory Bearings:
* Water pump: A failing water pump can cause a squealing noise when the engine is under load. Listen carefully to see if the noise seems to be coming from the front of the engine near the water pump.
* Power steering pump: A worn or damaged power steering pump can also squeal. Check for fluid leaks and listen for a whining noise when turning the steering wheel.
* Idler pulley: These pulleys can wear out and cause squealing. Inspect them for any signs of damage or wear.
* Tensioner pulley: If the tensioner pulley isn't functioning properly, it can cause the belt to slip and squeal.
3. Other Potential Causes:
* Engine oil: Low engine oil can cause a squealing noise, especially under load. Check your oil level.
* Engine belts: While you already replaced the alternator belt, double-check all other belts on your engine. They may be worn or damaged.
* Timing belt: While less common, a worn or damaged timing belt can also cause a squealing noise. This is a critical component, and you should have it inspected immediately.
* Engine components: Rarely, an engine component like a bearing could be failing, causing the squealing noise.
How to Diagnose:
* Listen carefully: Can you pinpoint the location of the squealing noise?
* Visual Inspection: Inspect all belts, pulleys, and accessories for wear, damage, or fluid leaks.
* Test drive: Accelerate slowly and listen for the noise. Does it change pitch or intensity?
* Mechanical inspection: If you are comfortable, you can check belt tension yourself using a tension gauge. If you are not comfortable, take your car to a mechanic for a thorough inspection.
Important Note: Never attempt to adjust belt tension without consulting a repair manual or a professional. Incorrect tension can damage the belt, pulleys, or even the engine.
Troubleshooting Tips:
* If the noise is consistent and doesn't change when you accelerate, it's more likely a belt tension issue.
* If the noise is intermittent, especially if it gets louder when you accelerate, it's more likely a bearing issue.
Be sure to address the squealing noise promptly. Ignoring it can lead to further damage and potentially a more expensive repair.
