Car manufacturers have faced an interesting dilemma since almost the first automobiles rolled off the assembly line. Your vehicle's engine is its only powerplant, but most cars include numerous other accessories. For example, every modern car has some form of power steering, air conditioning, numerous electronic accessories, and so on.

However, connecting the engine's crankshaft to these items wouldn't be practical. Instead, manufacturers typically use an accessory belt that transmits power from the crankshaft pulley to your car's alternator, power steering pump, and other critical accessories. The high stresses placed on this belt mean it will inevitably wear out, but is it still safe to drive your car once it begins to fail?

Recognizing the Signs of Belt Failure

Accessory belts rarely fail catastrophically or without warning. As the belt wears down, it will slip on the pulleys. This slipping typically produces a noticeable squealing or chirping sound. Sometimes, you may only hear this sound when you start your vehicle or on rainy and humid days. Note that healthy belts shouldn't make noise, but these conditions can exacerbate symptoms on older belts.

Most people replace their belts once they start squealing, partly because the noise tends to be annoying and embarrassing. If you take care of the problem once you start hearing noises, there's a good chance you won't experience any additional symptoms. Unfortunately, a slipping belt will eventually produce more than an unpleasant racket.

Since the belt is necessary to transfer power to your car's accessories, slippage will eventually reduce its ability to perform this job. You may notice dimming lights, issues with your power steering, or other problems. Once these symptoms develop, it's a sure sign that you need to schedule a replacement as soon as possible.

Understanding Why You Shouldn't Wait

While driving on a worn accessory belt won't usually damage your car, the consequences of a catastrophic failure can be costly or even dangerous. The longer you drive on a failing belt, the more likely it is that the belt will slip from its pulleys or snap. Unsurprisingly, a high-tension belt moving at high speeds can cause significant damage if it suddenly breaks.

At a minimum, a broken belt will stop your car dead and leave you stranded. Once the accessory belt snaps, you'll lose power to your vehicle's electronics, and, more importantly, the water pump and power steering pump will stop functioning. Even if the engine continues to run, it's crucial to pull over and shut the car off immediately to avoid further damage.

Ultimately, replacing a worn-out accessory belt is a relatively cheap and easy job. Although you may not notice any immediate effects of driving on a failing belt, a prompt replacement will help you avoid the much more expensive failures that can occur if the belt snaps. 

For more information, contact a local auto shop.