Serpentine Belts VS. V-Belts – Which Ones Are Better?

Ever wondered about the drive belts in your car’s engine?

You know, the things that drive the alternator, air conditioner, power steering, and other accessories?

Often referred to as a fan belt, although it’s no longer used to drive the cooling fan in modern cars if it fails it can leave high and dry with a potentially costly repair bill.

Serpentine Belts vs. V-Belts

Serpentine belts are the modern improvement on V-belts. Serpentine belts are more flexible and more compact than the older, stiffer V-belts. With the limited space in today’s compact engine bays, serpentine belts are better at driving multiple accessories in more complex configurations.

V-Belts

The V-belt is found mostly in older cars that have the engine mounted longitudinally in the engine bay. Often, more than one belt is used to drive the alternator, fan, air-conditioner compressor, and power steering pump.

As engine design advanced and smaller capacity, front-wheel drive vehicles became the norm, and space in the engine bay and on the engine became limited.

There was no room for a multitude of belts. Nor were the ribbed V-belts adequate to deal with the twists and turns necessary to reach the pulleys that were now squashed into a much smaller space.

This is where the serpentine belt became a necessity. Its lighter weight and more flexible construction allow a single belt to weave easily back and forth over all the pulleys.

Multi-ribbed V-Belts

Before serpentine belts were widely adopted, manufacturers were looking for ways to reduce slippage and make the V-belt more efficient.

They came up with the idea of introducing ribs into the V-belt design to reduce heat and keep the belt correctly aligned on the pulley. While this worked very well, the smaller ribbed V-belt was still only able to provide power to one or two pulleys. On more complex and luxurious engines, this meant running multiple belts.

Multiple belts meant higher costs and more space required.

Running multiple belts robs the engine of horsepower as there is extra weight involved in fitting additional pulleys with longer drive shafts. The V-belts themselves are also heavier than serpentine belts and the total length of the belt is longer when you must attach two or more belts to run multiple accessories.

V-belts also have less surface area in contact with the pulley. This results in a greater propensity for the belt to slip when under load. As the V-belt wears, it stretches and slips more, requiring regular adjustment of the tensioner to ensure that it can still drive the pulleys effectively.

Once the belt wears out, it can roll over in the pulley groove. You won’t necessarily realize that something is wrong as the belt will continue to provide some drive to the pulley and its associated accessory.

Unfortunately, it is in this scenario that the belt is liable to fail suddenly.

If your V-belt fails, you’ll either hear it as it snaps or you’ll notice that the alternator or battery light comes on.

The reason for this is that instead of the electrical power coming from your alternator, you’ll be draining your battery. If you are driving at night, then you’ll notice that your headlights will dim, and within a short period, your engine will die.

If you try to start your engine, the starter motor will not turn the engine over, as there will be insufficient power in the battery.

You’ll end up stranded, and unless you carry a spare V-belt or a pair of pantyhose to replace the broken V-belt, you’ll have to get a tow.

V-belts last between 30,000 and 40,000 miles before they need replacement.

Serpentine Belts

Serpentine belts were designed to provide a single belt solution to drive multiple pulleys.

Being wider and flatter, serpentine belts grip the pulleys more evenly. They also tend not to slip as much due to their greater contact area.

They don’t flip over on the pulley, so there’s less likelihood of them suddenly snapping when they wear out.

Due to their more advanced design and higher quality construction, serpentine belts last much longer than V-belts. Older neoprene belts last approximately 50,00 miles while the newer belts made from Ethylene Propylene Diene Monomer can last as long as 100,000 miles.

Fitting a serpentine belt is less complicated than fitting V-belts and they are easier to maintain too.

How to Replace a Serpentine Belt

When your serpentine belt starts to squeak or you see cracks in the belt, then it’s time to replace it.

The process is very simple. Before removing your old, worn serpentine belt, use a pen and paper to draw a diagram that shows exactly how the belt runs over the various pulleys.

You want to do this so that you know exactly how to put the new one on without missing any of the pulleys. If you can get a good photo of the belt and pulleys, then just use your mobile phone and refer to that when you put the new one on.

Once you have the diagram, locate the tensioner pulley. You do this by grabbing the belt and pulling on it. Look for the pulley that moves as you pull on the belt. It’s normally one of the top pulleys.

Using a serpentine belt tool, or a suitable socket wrench, loosen the bolt that adjusts the tensioner pulley. It’s located just below and to the side of the tensioner pulley. As you turn the bolt, the belt becomes loose and you can just slide it off easily.

Then take your new serpentine belt and slide it over all but the last top pulley.

Then push down on the tensioner pulley bolt and slide the belt over the last pulley. Check that the belt is properly located on all the pulleys and that its shape is the same as your initial diagram.

Then start the engine and check that the belt runs smoothly and that there are no squeaks.

Frequently Asked Questions About Serpentine Belts VS. V-Belts

Conclusion On Serpentine Belts VS. V-Belts

While older cars ran very well with V-belts, there were some shortcomings that made serpentine belts a better option.

They are more suited to the compact design of modern cars and, due to their lightweight, are more efficient than the older V-belts.

Serpentine belts are also quicker and easier to replace than V-belts, with the automatic belt tensioner ensuring that the belt is kept at the correct tension throughout its useful life.

This means it has less chance of rolling over on the pulleys the way a V-belt is inclined to do.