* Belt(s): This is the most common cause. The squeal is often due to a slipping serpentine belt (the one that drives most of the accessories). The squealing stops once the belt warms up and its friction increases. Check the condition of the belt for cracks, glazing, or wear. Also, check the belt tensioner – it might be worn out or not providing enough tension. A pulley could also be failing, causing the belt to slip.
* Power Steering Pump: A low power steering fluid level or a worn pump can cause a squeal, especially when the fluid is cold and thick. Check your power steering fluid level.
* Alternator: While less common to only squeal on startup, a failing alternator bearing can produce a high-pitched squeal that fades as it warms up.
* Water Pump: Less likely, but a worn water pump bearing could squeal initially, although this is more often a constant sound than one that disappears.
Troubleshooting Steps:
1. Check all belts: Visually inspect the serpentine belt for cracks, fraying, or glazing. If you see any damage, replace it. If it looks good, try checking the belt tension. You might need a belt tension gauge for an accurate measurement, but you can also gently press on the belt midway between pulleys – excessive give indicates low tension.
2. Check your power steering fluid: Check the level and condition of your power steering fluid. If it's low, refill it to the correct level. If it's dirty or dark, it might need to be flushed.
3. Listen carefully: Try to pinpoint the location of the squeal. This can help you narrow down the source.
4. Start the car and listen: Have someone help you – one person starts the car, while the other carefully inspects the belts and other components while the squeal is happening.
5. Professional inspection: If you can't identify the problem, take your car to a mechanic for a proper diagnosis. Describing the sound (high-pitched, low-pitched, duration) will help them.
Ignoring the squealing could lead to more serious problems. A slipping belt can lead to a damaged alternator, power steering pump, or other components. It's best to address the issue promptly.
