Skip the auto shop - Our mechanics make house calls

How Does a Timing Belt Work?

timing belt how it works

The timing belt is a belt made of rubber that keeps your camshaft and your crankshaft synchronized so that your valve timing is always right. Some vehicles have a timing chain instead of a belt, but it serves the same purpose. If your valve timing is off, your engine won’t run properly. In fact, it may not run at all. The belt also regulates the power steering and the water pump.

If you have timing belt problems, your mechanic can identify the trouble and will probably recommend that it be replaced.

How the timing belt works

In the four-stroke engine, there are four strokes, or phases. They are:

  • The intake stroke: The piston moves downward, and the intake valve opens to allow the mixture of air and fuel to enter the cylinder. At this stage, the exhaust valve remains closed.

  • The compression stroke: The piston moves up and compresses the fuel and air mixture. All valves are closed.

  • The combustion stroke: The piston moves down, allowing the spark plug to ignite the fuel and air mixture, delivering power to the vehicle. All valves are closed.

  • The exhaust stroke: The exhaust valve opens, allowing excess fuel and air to leave the engine. The intake valve is closed.

While all this is going on, the timing belt works to turn the camshaft pulley (some vehicles have two camshaft pulleys) in conjunction with the crankshaft pulley. A bad timing belt can cause the camshaft and crankshaft to be out of synchronization, and this can be catastrophic for the car’s engine. It throws the valve timing off, and you can end up with bent valves, bent piston rods, or completely destroyed pistons.

You may notice problems in time. Timing belt noise can be a red flag – it usually sounds like squeaking in the belt, or rattling if you have a timing chain. A timing belt problem should never be ignored, so watch for signs that there could be something wrong. The last thing you want is to have to rebuild your engine. As a general rule of thumb, you should plan on replacing the belt every 60,000 to 90,000 miles, or at least have it checked.

For this reason, your manufacturer will have recommendations as to how often your timing belt should be replaced. Generally, around the 80,000 mile mark it is prudent to get a mechanic to replace your timing belt to ensure that the engine continues to run efficiently.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Auto Safety Tips
Driving is more than a way to get from point A to point B. Owning and driving a car can also be a highly enjoyable experience. Whether a person is driving...


Related questions

Q: How do you deactivate or activate the Belt-Minder® system?

While the Belt-Minder® system in your car is designed to help ensure that you’re aware if a seat belt isn’t being worn, there may come a time that you need to deactivate (and then reactivate) the system. Here’s how: ...

Q: Isn't the timing belt suppose to be changed at 90,000?

I would definitely recommend changing the timing belt at the 90,000 mile recommended interval. As you may know, the timing belt keeps your engine's critical components in sync. Fortunately, this model does NOT have what is called an "interference" engine...

Q: How Long Should Belts in My Car Last?

Depending on the type of belts in your vehicle, they will probably last you anywhere from 3-10 years, or 40,000-150,000 miles. Typically, you will find the drive belt replacement schedule found in the owner's manual. This is assuming that the...