ASVAB (Armed Services Vocational Aptitude Battery)Auto and Shop Information (AS)Medium
A mechanic observes that a vehicle's serpentine belt is squealing loudly, especially during cold starts or when the steering wheel is turned sharply. Upon inspection, the belt appears moderately worn but not cracked. What is the most likely cause of the squealing noise?
- AA clogged catalytic converter.
- BA seized alternator bearing.
- CInsufficient tension in the serpentine belt.
- DAn overcharged battery.
Show answer & explanationAnswer & explanation
Correct answer: C. Insufficient tension in the serpentine belt.
A loose serpentine belt lacks sufficient friction to properly drive the accessories (like the power steering pump or alternator), causing it to slip and squeal under load, especially when cold or when accessories demand more power.
Why the other options are wrong
- A. A clogged catalytic converter would cause engine performance issues and exhaust restrictions, not a serpentine belt squeal.
- B. A seized alternator bearing would cause the alternator pulley to lock up, leading to immediate belt shredding or breakage, not just squealing.
- D. An overcharged battery is an electrical system issue and would not directly cause a mechanical belt squeal.
Serpentine Belt Squeal
A high-pitched noise caused by the serpentine belt slipping on one or more pulleys.
- Commonly due to insufficient tension or worn belt.
- Worsens with high accessory load (e.g., A/C, power steering).
- Can also be caused by misaligned pulleys or contaminated belt.
Memory trick: Slipping belt sings a sad song.