Belt-Related Issues (Most Common):
* Serpentine Belt: This is the most frequent culprit. A worn, cracked, or loose serpentine belt will squeal, especially when the engine is cold or under load (e.g., turning on the AC). Check for cracks, fraying, or glazing on the belt's surface. Also, inspect the belt tensioner; if it's worn or seized, it won't keep the belt properly tensioned.
* Power Steering Pump: If the squeal is worse when turning the steering wheel, the power steering pump belt might be slipping or the pump itself is failing.
* Alternator: A failing alternator can also cause a squeal, especially when the battery is low or under high electrical demand.
Other Engine Component Issues:
* Water Pump: A worn water pump bearing can produce a high-pitched squeal, often worse when the engine is cold.
* Idler Pulley or Tensioner Pulley: These pulleys guide the serpentine belt. If their bearings are worn, they'll squeal.
* AC Compressor: A failing AC compressor clutch can create a squeal, particularly when the AC is turned on.
Less Likely but Still Possible:
* Exhaust Leak: While less likely to sound like a *squeal*, a high-pitched whine from an exhaust leak near the engine is possible.
* Engine Internal Issues: While unlikely to be a squeal, a very serious internal engine problem could manifest as a high pitched noise, but would likely be accompanied by other symptoms like loss of power or overheating.
Troubleshooting Steps:
1. Listen Carefully: Try to pinpoint the location of the squeal. This will help narrow down the potential causes. Does it change with engine speed, or when you use certain accessories (AC, power steering)?
2. Visual Inspection: With the engine cool, carefully inspect the serpentine belt and all the pulleys and components it drives. Look for cracks, fraying, or any obvious damage.
3. Check Fluid Levels: Ensure that your power steering fluid and coolant levels are adequate. Low fluid levels can exacerbate problems.
4. Belt Tension Test: Try to press firmly on the serpentine belt midway between pulleys. Excessive deflection (give) indicates loose tension.
5. Start the Engine and Listen: With the hood open (but be careful of moving parts!), start the engine and listen closely. If the squeal stops when you spray a little water or belt dressing on the belt, it’s likely a worn or dry belt. (Do not use this as a permanent solution!)
Important Note: If you're not comfortable performing these checks yourself, take your 1997 Buick LeSabre to a qualified mechanic for diagnosis and repair. Ignoring a squealing engine noise can lead to more serious (and expensive) problems.
