Exploring Engine Rebuild Parts and Practices

Timing Chains vs. Timing Belts and Why They Matter

8 January 2019 by Rosa Wallace

Timing belts or timing chains are a feature of all modern vehicle combustion engines. The purpose of the belt or chain in your engine is to control the rotation of the camshaft, which in turn controls the valves, which are responsible for allowing fuel to enter the combustion chamber and exhaust gases to exit. It's possible that this isn't a component that you have given much thought, but without it, your car would not be going anywhere.

Chain or Belt?

The camshaft in your car is driven either by a metal chain or by a belt. Belts are generally constructed of rubber with reinforcing materials or cords embedded in them. If you do not know if your car uses a timing belt or timing chain, you should consult your manual or call your dealership to find out as soon as possible. While timing chains are generally considered to be maintenance free and last the life of the car, timing belts are wear items and must be replaced on a regular schedule.

How Do You Know If Your Timing Belt Is Failing?

Although timing chains are intended to last the life of a vehicle, belts will wear down and eventually fail. Timing belt failures are usually not caused by any single event, but rather just age and heat weakening the material over time. As the timing belt wears down, there are usually no major symptoms or issues with drivability. Even worse, since the timing belt is almost always protected by a cover and buried within the engine, it can be difficult to do a visual inspection. All of this means that timing belt failures are usually sudden and without warning, making it extremely important that they be replaced on a regular schedule as routine maintenance.

What Can Happen If a Timing Belt Fails?

First of all, a failed timing belt will always stop your car dead. Beyond that, the possible complications of a sudden failure range from nothing at all to catastrophic engine damage. Engines with timing belts are broadly categorized as either interference or non-interference engines. In non-interference engines, the valves are never capable of moving into the path of the pistons. In interference engines, only proper timing of the valve and piston motion presents the valves from coming into contact with the pistons and ultimately being destroyed.

The distinction between these two engine types is incredibly important when dealing with timing belt failures. In a non-interference engine, a broken timing belt will stop the engine dead, but there is no risk of additional damage. Once the timing belt is repaired, the car should be fine. For interference engines, there is a serious risk that the mistimed opening and closing of the valves will result in them contacting the pistons and being bent or destroyed. This is an extremely costly repair compared to simply replacing the timing belt as preventative maintenance.

Visit an auto parts shop for more information about timing chains and belts.

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