Why does my car squeal when I start it?

By Product Expert | Posted in FAQs, How To, Mazda Auto Repair Near Milwaukee, Mazda Service, Parts & Accessories on Monday, January 13th, 2020 at 3:48 pm
close-up on front of engine and serpentine belt

How to Stop Your Car from Squealing on Start-Up

Turning on your car just to have it squeal loudly is as annoying as it is embarrassing. Everyone with in earshot will look around and want to know where such a distinct sound came from. Luckily, about 90% of the time there is a single, easily-fixable culprit.

Let’s take a look at…

Why does my car squeal when I start it?


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What Makes Your Vehicle Squeal when Starting

mechanic working under the hood of a car

Most of the time, the squealing is do to something called a serpentine belt. When you open your hood, it’s the incredibly long belt that winds around multiple pulleys. It connects the crankshaft to other systems like the alternator, power steering, AC, and water pump. When it comes to your serpentine belt, there are three main reasons it could be squealing, all of which are easily fixed:

  1. Worn/damaged belt
  2. Loose tensioner
  3. Belt slippage

Worn Belt

Just like it sounds, this means the belt is old (roughly 100,000 miles or longer). This can range from the belt elongating, to worn edges, to worn-down teeth. It may also indicate that the belt is damaged. Either way, this requires the belt to be replaced. Serpentine belts aren’t particularly expensive, so don’t worry.

Loose Tensioner

The serpentine belt needs to be kept at a specific tightness and tension, which is the job of the aptly-named tensioner. On older vehicles, as materials and systems naturally degrade, the tensioner may not be able to stay at a specific setting. This can be fixed by readjusting the tensioner every once in a while (think of it like winding an old clock) or completely replacing the tensioner.

Belt Slippage

Do you park outside? Then you most likely have this problem. Cold and dew can affect the shape and grip of a serpentine belt. So if you start your vehicle and it squeals for a little while and then stops, this is your issue. This is more likely to occur in older belts, so replacing the belt is the easiest way to go about fixing it.

Need some help?

Order a new serpentine belt through us. If you want to avoid the hassle of replacing it yourself, then have us install it for you.

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