“Serpentine! Serpentine!” That’s the line in the original 1979 movie ‘The In-Laws’ with Peter Falk and Alan Arkin. In the movie, Arkin’s character, a New York dentist, is caught up in a crazy plot fabricated by Peter Falk’s character, an eccentric and wacky CIA agent. When Arkin runs out from behind a car and into the line of fire to get the keys to the car, Falk tells him to “Serpentine!” When Arkin runs back with the keys but forgets to “Serpentine!” Falk sends him back in the line of fire so he can do it right.

Fortunately for your car, truck or SUV, they don’t have to think about it. The serpentine belt, by its very nature, serpentines.

According to Meriam-Webster’s dictionary, the word is based on visual representation of a serpent moving through the grass. It weaves back and forth making a squiggly trail. That’s what the serpentine belt does – it runs a weaving pattern between the pullies at the front of the engine.

If a serpentine belt fails to serpentine, you’ve got trouble. That’s because, the only way a serpentine belt will fail to serpentine is if it breaks. I broken serpentine belt will fail to perform its primary duty – turning the pullies at the front of the engine.

What pullies does the serpentine belt drive?

• The Alternator Pulley
• The Power Steering Pump Pulley
• The Water Pump Pulley
• The A/C Compressor Pulley

These pullies are at the front of crucial components in your car and they must turn. If they stop turning, you’ll soon stop driving.

The Alternator Pulley keeps the alternator operating so that it is generating electricity that is crucial to the operation of the vehicle and the recharging of the battery. The Power Steering Pump Pulley turns the power steering pump. If that’s not turning, you’re going to find it a lot harder to turn the steering wheel.

The Water Pump Pulley turns the water pump that moves the coolant through the engine and out to the radiator where a fan pulls air through to carry away heat from the engine. Without it, the engine will overheat badly and soon. The A/C Compressor Pulley turns the air conditioning compressor. When that stops, the air conditioning stops working and you’ll find yourself getting rather hot.

The serpentine belt wends its way through and around additional pulleys. The crankshaft pulley turns the serpentine belt so that it can turn all the other pulleys. The belt tensioner, along with idler pulleys, maintains the serpentine belt at the proper tension.

The thing is that the serpentine belt drives all those pulleys at once. By winding its way through them, it makes contact with them all at the same time. If the belt breaks, non of those pulleys will turn. This means you’ll lose the electricity from the alternator, the steering assist from the power steering pump, the engine cooling effects of the water pump and the personal comfort effects of the air conditioning and all at the same time.

Serpentine belts are relatively durable; they don’t break often. But they do break. And when they break, the driver of the car has problems. They’re not going too far until that serpentine belt is replaced.

Usually, the serpentine belt will only break after a substantial amount of wear. A qualified auto repair technician can quickly spot signs that a serpentine belt is nearing the point where it should be replaced. Replacing it in your time, rather than waiting for the belt to break and let you down on its time, makes as much sense as not running out into gunfire to “Serpentine!”