Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. How Does a Timing Belt Work?

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

The Traveler’s Guide to Driving in Malaysia
CraigBurrows / Shutterstock.com Malaysia is a popular destination for many tourists today. The country has amazing sights and attractions that you will want to explore....
How to Get a Louisiana Driver's Permit
s licensing program. The first step in this program is to obtain...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...

Related questions

Q: Q: Belt came off

The most common cause of the belt coming off is the belt tensioner or idle pulley. They should be inspected before a new belt is installed. I recommend you seek a mechanic like the certified ones from YourMechanic to come...

Q: Timing chain broke, is my car not fixable now or do I have bent valves?

Unfortunately, your engine - as most engines today - is what is considered an interference engine. The timing belt/chain is responsible for keeping the internal engine parts moving in the correct time. Interference refers to the fact the intake and/or...

Q: The belt came off the pulleys

One of the first things that should be checked when dealing with a serpentine belt that has come off would be to check that all of the pulleys that are used for power steering, water pump, idler pulleys, alternator, crankshaft,...