Timing chain versus timing belt: a primer

Knowing if there’s a timing chain versus a timing belt in your car, and what exactly they both do, can help you save on expensive maintenance, costly repairs or both. Although it might seem like an overly technical subject, understanding a timing belt versus a timing chain is a fairly simple concept to grasp once you strip away all the jargon.

What is engine timing?

Your car’s engine needs to breathe air to produce power, so the heads sitting on each of the cylinders are packed with a series of valves. Each cylinder has its own set of valves, some for taking in clean air, and some for expelling exhaust gases, designed to open and close at very specific intervals.

“Engine timing” is the rate, duration and open/close time of each valve, and it requires a close link between the camshaft, which controls the valves, and the crankshaft, which is rotated as the pistons in your engine’s cylinders go up and down. Working together in harmony, valves and pistons will produce efficient power, but if things are off, they can physically bump into each other and cause significant internal damage.

Timing belts hold it all together

Enter the timing belt, which is a rubber belt that’s reinforced with a number of synthetic fibers linking the camshaft to the crankshaft. Always in motion, the belt conducts the mechanical symphony in the cylinder head and makes sure no component gets out of sync.

Unfortunately, wear can cause a timing belt to slack, stretch, or in some cases, even snap. The former will lead to an engine that’s not running at peak performance as valves miss their cues, while the latter can be a catastrophe if valves operate out of control and hit pistons at a high rate of speed. This is why each car has a specific timing belt change interval, which is usually about 60,000 miles, although in some cases it can be extended to 100,000 miles, before you have to change it out. (Consult your vehicle’s owner’s manual for the specific replacement interval.)

Timing belt versus a timing chain

A timing chain is a variation on the timing belt concept, but instead of rubber, the chain uses inflexible metal. The advantages of a timing chain versus a timing belt include nearly zero maintenance, which is good for motors stuffed into tight engine bays where access to timing belts or chains is difficult. Some timing chains are good for the life of the car, but others will require eventual replacement, or at least the servicing of the timing chain tensioner, which serves to keep the system taut.

Timing chains are a great substitute for belts, but they aren’t used universally. This can be due to packaging decisions under the hood, noise considerations or cost-saving measures by an automaker. Knowing which one you have in your car is as simple as asking your mechanic during the next service appointment, or just cracking open your vehicle’s owner’s manual.

Contact the service advisors at Protech Auto Repair for continuing maintenance on your vehicle and for more information on timing belts and timing chains. They can be reached at (661) 822-1100 and are located at 410 West J St., #G, Tehachapi.