What is a Timing Belt , Serpentine Belt & Timing belt Kit

What is a Timing belt?

Timing belt definition “Timing belt is one of the most important machine elements. It helps to transfer power and rotational motion in a completely synchronized manner”. 

Unlike a simple flat belt or a V-belt, a timing belt has teeth on its inner surface. These teeth are very similar to the gear teeth and they work the same as gear teeth. 

Pulleys used for timing belts also have teeth on them. These pulleys are very much like gears. The timing belt and pulley teeth work together to deliver power and rotational motion in a completely synchronized manner.

Due to their teeth timing belts cannot work on a simple flat belt or V-belt pulleys. Similarly Flat and V-belts cannot be used in place of the timing belt.

To read complete timing belt guide we recommend you our article on Timing Belt Material, Types, Applications, Advantages and Disadvantages


timing belt moving over a timing belt pulley
timing belt and timing belt pully

What does a timing belt do?

Timing belt works to deliver mechanical power and rotational motion in a fully synchronized manner. 

In an internal combustion engine timing belt works to deliver a synchronized motion between the engine crankshaft and camshaft. This is the reason that the timing belt is also known as a cambelt.

The engine crankshaft works to reciprocate the piston whereas the camshaft works to open and close the fuel inlet and exhaust gasses outlet valve. 

Synchronization provided by the timing belt ensures that valves opening and closing work perfectly with the piston reciprocating motion.

If synchronization between the crankshaft and camshaft fails due to a bad timing belt then engine working and performance will be highly compromised. 


Timing belt in an IC engine with serpentine belt
timing belt on an IC engine

Other than the I.C engine there are other timing belt applications 

When to do Timing Belt Replacement in Engine

Timing belt replacement is something that cannot be delayed once needed. As it is main component that synchronize the engine work, so any issue with it will directly effect the engine performance.

So when to do timing belt replacement? It all depends on three thing.

  • Timing belt mileage life of 60,000 to 100,000 miles has been complete
  • Timing belt life in years that is of 4 to 6 years is over
  • Timing belt is showing any of the following bad symptoms

We recommend you to read our article on Timing belt Replacement, Cost, & Bad Timing Belt Symptoms

What is a Serpentine Belt

Serpentine belt is an other part of car that work with engine crankshaft to deliver power to different car components. 

Serpentine belt connects car air conditioning compressor, alternator, and power steering motor. Serpentine belt take power and rotational motion from engine crankshaft and deliver it to these components so that they can work properly.

Its just like a regular V belt and is made of same material like rubber, urethane, Neoprene, and Polyurethane.

In an engine serpentine belt has multiple V belt groove across its width and can deliver power and rotational motion at quite a high torque.

What does a Serpentine Belt do

Serpentine belt work to deliver power to different car components like air conditioning compressor, engine alternator, and power steering motor.

Without the serpentine belt there will be no power for car air conditioning compressor so it will not work at all. Without the compressor there will be no fluid motion and working of air conditioning unit.

serpentine belt with idler and alternator
serpentine belt with idler and alternator

Similarly without serpentine belt there will be no power for power steering motor so it will not work either. Without power steering motor it will hard to turn the steering wheel thus very difficult to drive the car.

With bad serpentine belt there will be no power for car alternator and with alternator at stalled there will be no power for charging car battery. Soon battery will be fully discharged and it will be very difficult to start the car.

What is Timing belt Kit

When timing belt replacement is needed, its done by replacing the a complete set of timing belt kit. 

Timing belt kit includes; timing  belt, timing belt idler pully, timing belt tensioner, and water pump.

All these components are recommended to be changed with timing belt as these components will have the same life as of the timing belt and have same life span as of timing belt.

Other than life the new timing belt teeth may not set well with old water pump pulley and thus can compromise the working of engine.

What is timing belt tensioner?

Timing belt tensioner is a part of timing belt kit and engine timing setup. This tensioner help to adjust the tension of the timing belt during installation, inspection, and regular maintenance.

timing belt tensioner with timing belt on it
timing belt tensioner with timing belt on it

Timing belt tensioner is just like a flat belt pulley with a spring loaded center bolt. It does not engage the timing belt from its teeth side rather it is in contact with belt from its outer surface.

Position of the tensioner can be adjusted up to few millimeter to adjust the tension of timing belt. Simple rotate the tensioner bolt and adjust its position and tension of timing belt.

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