A broken timing belt can spell trouble for your car (and also for your budget), so it’s important to know the warning signs that a timing belt is wearing out. But it’s also critical to understand what it does and how it affects your vehicle’s performance.

One of the things that makes it difficult to check on timing belts is that they’re sealed in their own cover, which helps protect them from the oil and dirt circulating around an engine. They need to be protected because they're one of the most important elements under the hood; your car can’t run without them and a broken belt can cause severe damage to the engine.

Most timing belts are made out of rubber but also are reinforced with nylon cords to give them extra strength. This allows them to do the hard work required to rotate the cam and crankshaft so that all the engine’s cylinders fire at exactly the right time. Your engine relies on the pistons and valves to sync up perfectly and, if they don’t, your engine won’t run smoothly. In extreme cases, it won’t run at all.

While most older cars have a timing belt, many manufacturers have switched to using metal timing chains in newer vehicles. The chain serves the same purpose as the belt but is made of metal instead of rubber, which makes it last longer. (The downside of that is that when a timing chain breaks, because it's made out of metal, it can cause greater damage to the engine.)

You can check your owner’s manual to see whether your car has a timing belt or a timing chain. If you don’t find a maintenance schedule for the timing belt, the chances are good that your car has a timing chain. If you don’t have an owner’s manual, do an online search of your car’s make, model and year to find out which one is under your hood.

If you have a timing belt, it’s a good idea to learn more about what warning signs to look for, when to take it in to see a professional and what to do if it breaks.