Timing belt vs timing chain: what’s the difference?

What do timing chains and timing belts do?

A modern four-stroke engine works on the cycle of ‘suck, squeeze, bang, blow’. It describes pulling in air to the cylinder, mixing it with fuel, compressing the mixture, introducing a spark that initiates combustion, and then releasing the exhaust out of the cylinder. All these actions have to happen in precise coordination for the engine to produce power and not blow itself up.

Your timing chain or belt is connected to the crankshaft pulley at the bottom of the engine and to the camshaft pulley or pulleys at the top of the engine and is designed to turn the camshafts at a precise ratio, compared to the crankshaft, so that the dance goes off without a hitch.

In many modern engines, the valves that open for air and fuel intake and exhaust output actually share space with the moving piston, although never at the same time. This style of engine is called an interference engine and, as you can imagine, creates a requirement for those valves and pistons to be perfectly coordinated. If they step out of alignment for even a moment, the piston can strike and damage the valve, rendering the engine inoperable.

You might think that this is a terrible engineering decision, but interference engines are able to maximize efficiency and improve power delivery as a result of their risky engineering, so they’re here to stay.

The difference between timing chains and timing belts

Early vehicles used chains or gears to manage the timing and belts only became common in consumer vehicles during the 1960s. In the 1990s, automakers moved back to timing chains and modern cars tend to have a timing chain.

Timing Belts

Timing belts are made of rubber and reinforced with other materials like Kevlar to add strength and stretch resistance. Some advantages of timing belts are:

• They are lighter than timing chains, which benefits efficiency
• They are simpler and less expensive to produce
• The are quieter than timing chains
• They don’t require lubrication to operate properly

Timing Chains

Timing chains are typically made of steel and have these advantages over rubber timing belts:

• They rarely stretch if lubricated properly, so provide consistently accurate timing
• Their service life is much longer than a rubber belt – often the service life of the vehicle
• They almost eliminate the fear of a catastrophic timing failure

What are the maintenance costs for both?

The maintenance costs for a vehicle with a timing chain is mostly related to your oil change interval. If you change your oil regularly, according to your manufacturer’s recommendations, it will protect the timing chain and keep it in peak condition for a long time.

A timing belt does not require lubrication, and in fact, any oil or engine fluids that touch the rubber belt can damage the material and lead to failure over time. This is why timing belts are installed in a “dry” setup, away from engine fluids, while timing chains are lubricated in a “wet” setup.

Timing belts do need to be replaced at a regular service interval, usually around 60,000 to 100,000 miles, and that cost can be extensive, since it requires the touch of an experienced mechanic. If you install a timing belt improperly it can severely damage the engine. Expect to pay between $100 and $400 for the parts and between $400 and $1,000 for the labor to replace your timing belt. Also, if your water pump runs off the timing belt then it can be wise to replace that at the same time, to avoid the extra cost down the road.

How long do timing chains last compared to timing belts?

Timing chains last much longer than belts, especially when maintained properly. One of the best things you can do for your timing chain and your engine as a whole is to provide regular oil changes and always replace the oil filter at the same time.

Every manufacturer has a prescribed replacement interval for vehicles that use a timing belt, and you should honor that interval. Remember that a timing belt replacement may cost up to $1,000, but an engine timing failure can do much more damage and cost you several thousand dollars to repair.

Which one should you get?

Every vehicle has either a timing belt or timing chain specified as the OEM part, and you should always replace your chain or belt with the equivalent part. All the pulleys and gear sets that make up the timing system in your car will be set up for either a chain or a belt and it’s not advisable, or even possible, to swap them out.

Can I do this repair myself?

Cars are all put together by people just like you, and you can do all kinds of work on your vehicle as long as you take your time and follow repair guidelines precisely.

If you decide to attempt the repair yourself, consult your owner’s manual for any specifications, do research online to prepare for the repair and get all your timing belts and chains at AutoZone. Many timing belts can be purchased with accessory parts, like gaskets, pulleys, tensioners, and even water pumps, in a kit that makes the overall cost less impactful.

One very important step when replacing a timing belt is to carefully mark the position of the crankshaft pulley and the camshaft pulleys before you remove the original belt. You may also need to use a special tool to hold the camshafts in place.

If you are wary of doing this slightly-complicated repair yourself, check AutoZone’s list of Preferred Shops in your area and rely on trusted professionals to make the repair.