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How to Detect a Faulty Radiator Fan Belt

The radiator fan belt is attached to a pulley, or series of pulleys, and turns your radiator fan at a speed sufficient enough to draw ambient outside air into the radiator. Some vehicles use a belt dedicated to turning the radiator fan only; however, many vehicles use a serpentine belt to not only control the radiator fan but many other components of the vehicle such as the power steering, air conditioning and even the alternator. Serpentine belts or radiator belts are usually designed to last up to 150,000 miles.

These belts occasionally wear out. Older vehicles (those more than 8 to 10 years old) may not use the same type of high quality belts used in newer vehicles, and may need to be replaced every 40,000 or 50,000 miles.

Symptoms of a Bad Radiator Fan Belt or Serpentine Belt

One of the very first symptoms that a radiator fan belt or serpentine belt going bad is squealing or screeching sounds that come from the engine area. The sound may only last for a minute or two after starting the vehicle. Over time, the squeaky belt sound will grow louder in volume and continue for longer periods of time. The volume of the sound will vary from vehicle to vehicle, but it’s almost always annoying and noticeable.

The noise is the result the belt slipping off the pulley because of corrosion on the belt. Regardless of whether the sound occurs only when you’re starting the vehicle or when accelerating, the noise usually indicates the belt needs to be replaced.

Visual Signs of Radiator Fan Belt Damage

One of the easiest ways to diagnose problems with a radiator fan belt or serpentine belt is simply to look at the condition of the belt. A worn or slipping belt will usually show signs of damage such as fraying or cracking, and can easily be seen using a flashlight and a small mirror to view the underside of the belt.

Many mechanics recommend that you change a worn belt whenever there are two or more cracks per inch in the belt. Worn belts can also show signs of cording and ribbing. If you have these types of defects in your radiator fan belt, consider purchasing a new belt right away. If you have a crack that is deeper than half the thickness of the belt, you should change the belt immediately, because it will probably break or snap soon.


(Article originally appeared on – Image copyright – Bentaboe / 123RF Stock Photo)