Things to Know About Engine Timing Belt - Service Information at Capitol Chevrolet

Most drivers know that a broken timing belt is bad news, but many don't know much else about this component--including whether their vehicle has one or not! At Capitol Chevrolet, we want to help you learn more about your Chevy, including what service it needs. Keep reading to learn more about timing belts.

Timing belt

5. What Does a Timing Belt Do?

In short, the timing belt synchronizes the movement of the crankshaft and the camshaft or camshafts. We realize that this short answer may be a bit oblique, so we'll go into a bit more detail!

When you're driving, combustion is continually taking place inside the combustion chambers, or cylinders, of your engine. For this combustion to happen, precise timing is necessary. In each cylinder, an intake valve will open to allow a mixture of fuel and air into the chamber. The intake valve closes, and a piston is pushed upwards into the cylinder to compress the fuel. A spark is lit, which causes the mixture to combust. This combustion pushes the piston back down, and an exhaust valve opens up in the cylinder to let the gases out.

Your engine will have one or more camshafts, which control the intake and exhaust valves. In addition, the pistons are attached to a crankshaft. This shaft converts the linear energy (caused by the piston moving up and down) into rotational energy. The timing belt makes sure that these shafts are synchronized so that the valves and pistons are always in the right place at the right time.

Broken piston connecting rod

4. What Happens When a Timing Belt Breaks?

It depends. If you have an older, non-interference engine (also known as a freewheeling engine), a broken timing belt will cause the engine to stop working until the belt is replaced. However, most modern engines are interference engines, which changes things greatly.

Interference engines are more powerful and efficient than freewheeling engines because they allow the pistons to create even more compression. They do this by making it so that a fully-extended piston occupies the same space in the cylinder that an open valve would occupy. This makes timing exceptionally important. If the timing belt breaks and the rotation of the camshafts and crankshaft aren't synchronized, the pistons may fully extend while the valves are open, striking them and causing massive engine damage. In cases like this, it's usually cheaper and better to replace the engine entirely rather than attempting repair.

3. Do All Vehicles Have Timing Belts?

No. Your car assuredly does have something to control the timing, but it's not always a belt. There are three main ways to control timing, though one isn't used as much as the others. The least-used method is actually the earliest: a timing gear. These gears are sturdy and won't snap, but they're also heavy and loud, making them less suitable for passenger cars. So, timing chains were invented. These work similarly to timing belts, and they're lighter than gears. Timing belts are actually a more recent way of controlling timing. They began to replace timing chains because they're even lighter and quieter. However, many modern vehicles have begun to be outfitted with chains again, since a timing chain should last for the life of the vehicle.

To find out whether your vehicle has a timing belt, check your owner's manual.

Worn timing belt

2. Why Do Timing Belt Replacements Cost So Much?

If your Chevy does have a timing belt, you'll find that replacing it is one of the most expensive automotive services. This is not because the part itself is expensive; as a simple rubber belt, it's actually relatively inexpensive. The difficulty comes in the labor. The timing belt is buried deep in the engine, so changing one means dismantling the engine. This alone takes hours of work, but it's not all they do. Generally, technicians will also replace the water pump, tensioner, and idler pulleys while they're replacing the timing belt. They'll also test the belt to make sure that the timing is correct before reassembling the engine.

1. How Will I Know if My Timing Belt Needs To Be Replaced?

The only reliable way to know this is to have it changed according to the service schedule in your owner's manual. This is because timing belts don't give reliable signals that they're going to break soon. That's not to say that there are no symptoms; for example, a timing belt that's worn down may make a ticking noise before it breaks. However, going by symptoms is a bad idea. A ticking noise can also be caused by a number of other things, so you may not know that it's the belt about to break. Also, timing belts don't always make this noise; sometimes they just snap with no warning. To avoid massive engine damage, make sure you follow the maintenance schedule in your owner's manual exactly.



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