Timing Belt vs Serpentine Belt – Know the Difference

Serpentine belts and timing belts are fundamental for the smooth operation of a vehicle’s engine. Knowing the differences helps them ensure their vehicle’s optimal performance and longevity.

This article will explore the differences between timing and serpentine belts. Learn how they differ in their design, function, and maintenance requirements.

What Does a Timing Belt Do?

The timing belt (cambelt) is responsible for synchronizing the rotation of the camshaft and crankshaft inside the engine. This coordination guarantees that the engine’s valves open and close at a precise time for smooth operation. The timing is set by the alignment of the pulleys when the timing belt is placed on them, it can also be adjusted afterward, but that’s a whole other thing.

Timing belts are forged from a rubber compound and deliver numerous advantages over other belts. These belts are known for being quieter and more efficient and do not require any adjustment once fitted to function appropriately.

The timing belt may not be there in some vehicles as a timing chain replaces it. A timing chain functions like a timing belt. The difference is that the chain is made of metal instead of rubber.

Timing chains commonly do not require a specifically timed replacement but are typically heavier and louder than timing belts. So they tend to snap with age.

Consequences of a Failed Timing Belt

When a timing belt fails, the engine’s valves will open at the wrong moment and can clash with the pistons. Not all engines have the ability for interference to occur. Either way, when the belt fails, it usually results in extensive engine destruction; depending on the vehicle’s age and condition, the repair cost can write a car off. Thus, taking preventative steps and replacing the timing belt at scheduled intervals will avert such a scenario.

If the car doesn’t have a belt but features a chain instead, it rarely causes any other damage when the chain snaps. In this instance, you replace the chain, time everything up, and away you go again.

When to Change a Timing Belt?

Timing belts typically have a lifespan of 50,000 to 90,000 miles and cannot be easily checked for wear and tear. Regardless, if taking the cambelt cover off to look at the belt, you cannot tell how the belt structure is holding up internally. As such, replacing the timing belt on a periodic schedule, as denoted in the vehicle’s manual, is very important.

What Does a Serpentine Belt Do?

The serpentine belt is a long continuous rubber belt that runs around the engine block, and the crank pulley drives it. A serpentine belt is also called a fan belt or an accessory/auxiliary belt that powers the alternator, power steering pump, air condition compressor, and on occasion, the water pump.

It generally features a belt tensioner in some form to ensure that the belt is at the proper tension to grip the pulleys without slipping.

What to Expect if a Serpentine Belt Fails?

A failed serpentine belt can affect multiple systems, such as the power steering, alternator, water pump, and air conditioner, causing issues for drivers. It’s not as catastrophic if the serpentine belt breaks as the timing belt; it may cause the car to shut off, but replacing the belt is all required to get the car back on the road.

When to Change a Serpentine Belt?

The time to change a serpentine belt varies between different vehicle models. Therefore, car owners should check their vehicle’s manual for the manufacturer’s specific recommendation on replacing the serpentine belt.

The owner’s manual should have any recommended service intervals. The best time to check the serpentine belt for damage or wear on most vehicles is 50 – 60,000 miles.

On 90% of vehicles on the road, the serpentine belt needs to be removed to replace the timing belt. Usually, the serpentine belt is replaced at the same time.

How to Tell the Difference Between a Timing Belt and a Serpentine Belt?

cambelt kit

Timing belt vs serpentine belt – visual differences

The difference between the two types of belts can be easily identified by investigating the ribs on the belt.

Timing belts feature V like grooves that resemble teeth and are specifically designed to mesh with the cogwheels of the camshaft and crankshaft.

On the other hand, serpentine belts feature multiple ribs running inside the belt. These grooves run vertically along its length, providing good traction on the component’s pulleys.

Timing belt vs serpentine belt – engine location

Consult the owner’s manual to deduce whether the vehicle is equipped with a timing chain or a timing belt first. You could spend all day looking for a belt that doesn’t exist!

Either way, the timing belt is not easily visible and requires considerable effort to access. The timing belt lies in the engine’s interior and is liable for synchronizing the camshaft and crankshaft.

In contrast, serpentine belts are positioned outside the engine. It is easily accessible and visible by popping the hood.

Timing belt vs serpentine belt – material construction

Timing belts and serpentine belts are made of rubber but are composed of distinct materials.

A timing belt features either a fiberglass-reinforced rubber or neoprene construction. This allows it to keep its shape, endure extreme heat and deter contamination from coolant or oil.

The serpentine belt is generally made of polymer-based rubber. This material construction gives the belt a soft and pliable exterior, enabling it to wrap around the crankshaft pulley and supporting accessories.

Timing belt vs serpentine belt – replacement

Most vehicle owners’ manuals recommend replacing serpentine belts and timing belts after 50k to 100k miles.

Replacing the timing belt involves dismantling the engine, including the alternator, timing cover, engine mount, and other engine parts. So replacing can take most of the day.

On the complete opposite, depending on the vehicle, an easily accessible serpentine belt can be replaced as quickly as 15 minutes.

Final Thoughts

In conclusion, knowing the differences between timing and serpentine belts is crucial for car owners to ensure optimal performance and longevity of their vehicles. It is important to replace the timing belt exactly when the manufacturers recommend.

Timing belts synchronize the camshaft and crankshaft, and failure can lead to catastrophic engine damage. While serpentine belts power multiple supporting components and failure can cause problems, it’s not so disastrous. It would be best to read more about what happens and what causes a serpentine belt to break next.

My name is Tom although my friends call me Tommy. Messing around with cars and bikes has always been a hobby of mine even from a young age. So I made it my day job 17 years ago. I am a fully qualified mechanic as you would expect. I've worked in all different areas of the motor trade, valeting, panel beating, engine repairs, I'm sure you get the idea. I enjoy sharing my wealth of knowledge and experience with others, which is the reason I spend a lot of time here writing for this website.

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