* Alternator Belt: Even if the tensioner is new, the belt itself might be worn, glazed, or slipping. Check for cracks, fraying, or glazing on the surface. A simple visual inspection and a feel test (is it stiff or pliable?) can help determine its condition. Replacement is relatively inexpensive.
* Serpentine Belt (if applicable): Many cars use a serpentine belt that drives multiple components. If it's worn or misaligned, it can squeal. Check its condition alongside the alternator belt.
* Idler Pulley(s): These pulleys guide the belt and can wear out, causing squealing. Look for signs of wear, such as roughness or play in the bearing.
* Water Pump Bearing: A worn water pump bearing can squeal, especially when the engine is cold.
* A/C Compressor Clutch: If your A/C is on, a worn compressor clutch can squeal. Try turning the A/C off to see if the noise changes.
* Power Steering Belt (separate from serpentine): Some cars have a separate belt for the power steering pump. Check its condition.
* Dry Belt(s): Sometimes, a squeal is simply due to a dry belt. Try spraying a *small* amount of belt dressing on the belt(s) while the engine is running. Do not overspray. This is only a temporary fix; if the squeal returns, the belt needs replacing.
Troubleshooting Steps:
1. Listen Carefully: Try to pinpoint the location of the squeal. Is it coming from the front, rear, or engine compartment? This can help narrow down the possibilities.
2. Visual Inspection: Thoroughly inspect all belts and pulleys for wear, cracks, and glazing. Look for any obvious damage or loose components.
3. Check Belt Tension: Ensure all belts have proper tension. Too loose, and they'll squeal; too tight, and they can damage pulleys. Consult your owner's manual for proper tension specifications.
4. Start with the Simplest: Replacing belts is relatively inexpensive and easy. Start with this before moving on to more complex repairs.
5. Professional Diagnosis: If you're unable to identify the source of the squeal, take your car to a qualified mechanic for a proper diagnosis.
Important Note: A persistent squealing noise shouldn't be ignored. Ignoring it could lead to more serious and expensive damage.
