Serpentine Belt vs. Timing Belt (What’s the Difference?)

(Updated on January 11, 2021)

Most car owners don’t understand the difference between the serpentine belt and the timing belt. Sometimes these two names are used interchangeably by people. However, the serpentine belt and timing belt serve two completely different purposes.

But they both are important parts of the internal combustion engine. In fact, the engine must be running for these belts to run as well. As they’re running, they assist other components of the vehicle.

Note: Some vehicles use a timing chain instead of a timing belt. Please see this article for how they differ: Timing Belt vs Timing Chain

The serpentine belt takes mechanical power from the engine and transmits it to several peripheral devices of the vehicle, such as the water pump, power steering pump, alternator, air pump, oil pump, and air conditioning compressor.

A timing belt, on the other hand, is responsible for keeping the camshaft and crankshaft movements synchronized. Let’s explore why these functions are so important to your vehicle.

Serpentine Belt

bad serpentine belt symptoms

The serpentine belt is a very long single belt which runs continuously. It is located on the exterior of the engine block. If you’re looking at your engine block, the serpentine belt is often easy to notice from the front.

It is long, black, thin, rubbery, and ribbed on the outside. The most important accessories of your car engine depend on the serpentine belt for their power needs.

The reason why it is called the “serpentine” belt is the belt acts like a snake. Not only is it a continuous snake-like belt, but it coils on these other accessories to provide them with power. If the serpentine belt were to fail for some reason, then all these peripheral engine accessories would malfunction or stop working altogether.

A failing serpentine belt will cause your engine to overheat and eventually stop running. The serpentine belt will usually fail due to age but also if coolant or oil from within the engine leaks out onto it. In other cases, the tensioner may be putting the wrong amount of tension on the serpentine belt, resulting in a misaligned belt.

Fortunately, serpentine belts are cheap to replace. Even if you need to go to a mechanic to have them replace your serpentine belt, the job is fast and simple. So, you won’t need to worry too much about the labor costs either.

See Also: Common Causes of Serpentine Belt Squealing Noise

Timing Belt

bad timing belt

The timing belt is located inside of your engine. It helps move the camshaft at times when the gears are unable to do it. More importantly, it allows the camshaft to open and close the intake valve and exhaust valve at the appropriate times. That way, the piston doesn’t hit them.

In certain types of internal combustion engines, the timing belt may also help run the oil pump and water pump of the engine. But in every engine, the timing belt’s main job is to keep the camshaft and crankshaft connected with its teeth.

The inside surface of the timing belt is where the teeth are located. The space between each pair of teeth is called the pitch. The belt itself is made from durable materials, such as welded urethane, neoprene, or molded polyurethane. These materials are made to last for a long time.

A failing timing belt is worse than a failing serpentine belt. If your timing belt doesn’t function properly, then it could cause permanent or expensive damage to your engine. The main consequence of a bad timing belt is your valves staying open and getting struck by the piston.

To keep your timing belt strong, it is important that your engine is doesn’t run too hot or leaks oil. Overheated engines and oil leaks are the two biggest causes of timing belt failure. It’s important to check your owner’s manual for the specified timing belt change interval and actually do it.

But if you notice your timing belt is showing signs of wear, spending a few hundred dollars on a timing belt job is much better than the alternative on a new engine. Get the replacement job done immediately to prevent your engine from getting damaged.

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