Serpentine Belt vs Timing Belt: What’s the Difference?

If you’re like me and forget automotive parts more often than not, then timing belts and serpentine belts are easy to mix up. After all, they’re both belts, but beyond that, they couldn’t be more different. From location and material to their essential role in your car’s engine, each has different maintenance schedules you ought to know about.

is a serpentine belt the same as a timing belt?

Don’t get confused—a serpentine belt is not the same thing as a timing belt. The serpentine belt and timing belt have very different functions in your vehicle.

The timing belt is located inside the engine and keeps the crankshaft and camshaft in sync. This ensures that the engine intake and exhaust valves open and close in time with the pistons so the engine runs smoothly.

The serpentine belt is what keeps the engine accessories running smoothly and efficiently. It connects the engine crankshaft on the outside of the engine to all of the engine accessories.

You can easily tell the difference between the two when you look at the grooves. A timing belt has horizontal “teeth” designed to fit the cogwheels of the crankshaft and camshaft. A serpentine belt has multiple V-shaped grooves that run vertically along the belt.

Over time, these belts need to be replaced (roughly around the same time). You can always ask your trusted mechanic or refer to your owner’s manual for more instructions.

What Are Drive Belts? Serpentine Belt vs. Timing Belt

Most modern, fuel-powered cars have two drive belts, the serpentine belt and the timing belt.

Serpentine Belt vs Timing Belt

Timing Belt:

The timing belt opens and closes engine valves in conjunction with a vehicle’s pistons and allows the crankshaft to turn the camshaft. To simplify things in a way that would pain a mechanic, the crankshaft and camshaft are the foundation of your car’s engine.

Together, they ensure that the engine correctly goes through the intake, compression, power, and exhaust strokes, enabling your car to operate smoothly.

  • Location: The timing belt can be found inside the engine.
  • Function: The timing belt is the belt that controls the camshafts in your engine, opening, and closing valves at just the right time for smooth operation. The timing belt has teeth that turn the camshaft in time with the crankshaft.
  • Appearance: A timing belt has horizontal “teeth” that are made to fit both the crankshaft and camshaft.

Serpentine Belt:

The serpentine belt powers various engine components, including your alternator, power steering pump, air conditioner, and more.

Simply put, your serpentine belt powers many of your car’s functionally necessary and quality-of-life features (for example, your alternator charges your battery and other electrical components such as infotainment systems).

  • Location: The serpentine belt is found outside of the engine and easily visible when you open the hood.
  • Function: Serpentine belts help power your alternator, steering pump, and air conditioning, in some vehicles it powers water pumps.
  • Appearance: A serpentine belt has multiple V-shaped grooves that appear vertically along the belt.

Serpentine Belt Vs Timing Belt: When should you Replace?

Your serpentine belt is made to last a long time. Under ideal circumstances, your car’s serpentine belt should last 60,000–100,000 miles. It’s crucial to renew this belt as part of your vehicle’s scheduled maintenance, even if it still looks like it’s in good condition.

Serpentine belt replacement costs usually run around $100-250, depending on the vehicle – it’ll hurt your wallet a lot less to replace a serpentine belt versus a timing belt.

Timing belt replacement requirements vary by vehicle, so check your owner’s manual, but generally, timing belts last between 60,000-100,000 miles.

Replacing a timing belt usually costs between $400-1,000, depending on the type of car (some timing belts are harder to replace than others). If you want to minimize timing belt replacement costs, do so before it breaks – because broken time belts often result in other damaged parts, replacing a broken time belt can easily double the cost.

Symptoms of Bad timing belt vs serpentine belt

Bad Timing Belts Symptoms:

Here are some of the signs you need to look out for if your timing belt is bad and needs to be replaced:

  • Ticking noise coming from the engine
  • The engine won’t turn over.
  • The engine acts up between 2,000 – 4,000 RPM.
  • The engine misfires.
  • More smoke and fumes than normal
  • Oil leaks from the front of the motor

Bad Serpentine Belt Symptoms:

You should become familiar with the following six symptoms that may show signs that your serpentine belt is beginning to fail and may need replacement:

  • Squeaking, squealing or chirping sounds from under the hood of the car.
  • Check engine light or battery light is illuminated on your dashboard.
  • A/C isn’t working.
  • The power steering isn’t working.
  • The engine’s temperature is high or overheating.
  • The smell of burnt rubber.

Additionally, if you do a visual inspection of the serpentine belt when the car is turned off, you can look for these signs of wear:

  • Cracks splits, or fraying
  • Signs of glazing on the belt’s sides
  • Separating layers or missing chunks of grooves when you twist the belt.

Differences Between Serpentine Belts and Timing Belts

As previously mentioned, serpentine belts and timing belts are used for different purposes. Serpentine belts are designed to activate motor-driven parts and systems, whereas timing belts are used to synchronize the camshaft with the crankshaft.

Another difference between serpentine belts and timing belts involves the material from which they are made. Serpentine belts are typically made of rubber or a polymer-based material. They are soft and somewhat elastic.

Timing belts are still made of rubber as well, but they are reinforced with fiberglass. With their fiberglass-reinforced construction, timing belts are inherently stronger than serpentine belts.

While all vehicles have one or more serpentine belts, they may or may not have a timing belt. Some vehicles have a timing chain instead of a timing belt. Timing chains serve the same purpose of synchronizing the camshaft with the crankshaft. They are simply constructed of metal links rather than solid and looped pieces of material.

DifferenceSerpentine BeltsTiming Belts
LocationOutside engineInside engine
FunctionalityRuns power accessories bolted to the engineTurns the camshaft(s) which open and close the valves
LengthNot more than 0.5 inches of deflection when twisted in the middleShort diameter
Stretch TensionNot more than 0.5 inches deflection when twisted in the middle10% to 30% slackness
Groove DesignHorizontal “teeth”V-shaped grooves
Lifespan50,000 to 60,000 miles60,000 to 100,000 miles
Cost of Purchase$25 to $75$20 to $100
Replacement Cost$100 to $250$400 to $1000

Long story short, there is no “timing belt versus serpentine belt” comparison – they may work together, but both serve distinct functions. Your drive belts are instrumental to your car’s longevity – without them, you aren’t going anywhere fast. To be precise, you’re going nowhere at all.