Why Does My Car Squeal When I Start It?

Unless you live on a farm, a loud squealing noise first thing in the morning can be very off putting, especially when the squeal is coming from your car. So what does it mean when your car emits a loud squeal when you first turn it on?

You likely have a damaged or failing serpentine belt, also known as the drive belt. The serpentine belt is a long rubber belt that is snaked through a series of pulleys in your engine and provides power to peripheral systems such as the alternator, power steering, air conditioning, and water pump.

So what exactly causes your car’s serpentine belt to emit a squealing sound? There are two primary causes for a failing serpentine belt.

  • The Belt is Worn or Damaged: Drive belts are designed to last a long time, but they don’t last forever. Most likely, your drive belt has reached its life expectancy and simply needs to be replaced. Since most drive belts are made of rubber or a rubber-like material, external factors like heat and humidity can cause the belt to become cracked or the friction from being pulled through the pulley system can cause the belt to become loose.
  • The Belt Tensioner is Failing: As the name suggests, the drive belt tensioner is in place to ensure proper tension in the drive belt as it winds through the pulley system. If the tensioner allows the drive belt to become too loose, the belt can become misaligned or fall off. If the tensioner allows the drive belt to become too tense, the belt can crack or break. Either way, you won’t be getting too far.

Aside from the loud squealing, your vehicle will likely give you several other warning signs including:

  • Illumination of the Battery Warning Light: The serpentine belt powers your vehicle's alternator which charges your car’s battery. Thus, if your serpentine belt is failing, it will provide less or no power to the alternator which in turn causes your battery not to maintain its charge.
  • Engine Overheating: The serpentine belt also powers your vehicle's water pump which is designed to help keep your engine cool, so if your drive belt can’t power your water pump, then your water pump can’t keep your engine cool.
  • Difficulty Steering: Your car’s power steering pump, which is powered by the serpentine belt, is part of your power steering system that makes it much easier for you to turn your 2000+ lb vehicle. If you start to notice that it is becoming very difficult for you to turn your steering wheel, the root cause may lie with the serpentine belt.
  • Poorly Functioning Air Conditioning: Your vehicle’s air conditioning is also powered by the serpentine belt so poor air conditioning function, including blowing less than cool air, could also be a symptom of a failing serpentine belt.

Since drive belt failure could render your car unable to operate and leave you stranded on the side of the road, it is imperative to take action at the earliest signs of failure. At Wilton Auto and Tire Center, we recommend having your serpentine belt inspected by a trained automotive technician as soon as you begin to hear squealing and replace the serpentine belt if recommended by the repair technician. However, regular maintenance can prevent you from ever having to reach that point as it allows your mechanic to notice potential issues before they have a chance to occur.

Written by Wilton Auto & Tire Center