Timing Belt vs. Timing Chain

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Timing Belt vs. Timing Chain

All engines, whether old or new, must have a mechanism to open and close the valves. Valves are what allow fuel and air into the engine, and allow exhaust gasses to exit. The valves are opened and closed by one or more camshafts, which is where the timing system is needed. The camshaft has to be connected to the main rotating crankshaft of the engine by some type of mechanical system. This system is not only needed to turn the camshaft, but also ensures that the camshaft and crankshaft remain perfectly synchronized while the engine is running. Almost all cars and trucks on the road today use either a timing belt or a timing chain. A rare few will instead use gears, while electronically driven valves are in the technology pipeline. In most cases, the first step in maintaining the timing system is to determine whether the car uses a belt or a chain.

A quick search for the specific vehicle on eBay Motors will often reveal which type of timing system is used, but a service manual is the best way to find out for sure. Knowing the types of timing systems, and the maintenance involved with each will allow car owners to keep their cars in safe driving condition. This information is also important for used car buyers to determine if cars have been properly maintained, and to choose the right car for their needs.

Timing System Maintenance

The timing system is a critical aspect of every car’s powertrain. While it does not need to be maintained often, it is very important that car owners follow the manufacturer’s scheduled replacement intervals. While timing belts are less expensive than timing chains, they need to be replaced more often. For cars with belts, the maintenance interval is generally between 50,000 and 90,000 miles. For cars with timing chains, intervals over 100,000 miles are common, although the manufacturer may recommend checking the condition of the timing chain at more frequent intervals. This is one of the most important maintenance areas for car owners to be aware of, and perhaps the most important to follow on schedule.

Interference Engines

Timing belt or chain replacement is especially important for certain cars that have "interference engines." These engines will be severely damaged if there is a failure of the timing belt or timing chain while the engine is running. When the valves in an engine’s head open, they are pushed into the cylinder toward the piston. Under normal operation, the valves are never intended to be open while the pistons are near the top of their travel. However, if the camshaft stops turning due to a timing failure, some of the valves will remain open as the pistons cycle through their stroke.

In an interference engine, the space between the piston and the cylinder head is so small that the piston will make contact with any open valves, inevitably bending them. This condition will always lead to replacement of the heads, if not an entire rebuild of the engine, either of which will come with a staggering price tag. While there is nothing inherently wrong with the interference design, which is commonly needed on high performance engines to generate high compression, it does require strict adherence to the maintenance schedule. It is especially important for buyers of used cars to ask the previous owner for documentation of timing belt or timing chain maintenance. In most cases, if the mileage on the car is near or over the scheduled replacement interval and there is no documentation, the maintenance should be done as a precaution.

How to Maintain the Timing System

When it’s time for a new timing belt or timing chain, there are several sources for these parts. Car owners that use a mechanic for maintenance may find that purchasing the parts in advance is less expensive than having the mechanic purchase them. Owners who prefer OEM parts may also choose to buy the parts themselves. Do-it-yourselfers with the skill to do this type of work themselves should consult a service manual to ensure that proper procedures are followed, including torque specifications for bolts and sealing methods. New gaskets should always be used when replacing covers.

Torque guidelines are very important in this part of the engine, especially when aluminum parts are used. The timing of the camshaft must be set exactly, otherwise the engine will not run properly, and in the worst case, it can be severely damaged. Maintenance procedures for some cars with timing belts will call for replacement of the water pump during this service. This is done as a precaution in systems where the timing belt directly drives the water pump, and a water pump failure would at the very least require the job to be done again, and at worst could cause the timing belt to fail. In most cases, it’s best to leave this type of work to a professional.

Pros and Cons of Timing Belts and Timing Chains

Automotive engineers take into account a wide variety of factors when they design the engine’s timing system. Prior to the 1960s, advanced materials were not available for this purpose, thus the chain method was almost ubiquitous. With the advent of high strength polymer materials, engineers were able to delve into more varied designs, leading to the first use of timing belts. While various constraints factor into the design choices, the initial motivation for investigating these designs was likely the reduced manufacturing cost, while the decreased noise was an added bonus.

Benefits of Timing Belts

Timing belts offer additional advantages besides lower cost and lower noise. In particular, the low inertia of a belt can be beneficial in certain applications. Many modern engines use an overhead cam design, which eliminates the need for long valve pushrods, but significantly increases the distance between the crankshaft and camshaft(s). When a timing chain is used in these engines, the distance results in a very heavy chain. The high inertia of the large chain becomes problematic at high RPMs, so a belt is often preferred in these cases. Nonetheless, in recent years more manufacturers have been moving back to chains, even in overhead cam engines.

Benefits of Timing Chains

The main drawback of timing belts is their tendency to break. While sudden failures are quite rare on properly maintained engines, it does happen from time to time. Chains, on the other hand, almost never break, even when pushed beyond their normal service limits. This results in a considerably longer maintenance interval for timing chains as compared to timing belts. It also means that catastrophic failures in interference engines are highly unlikely when a chain is used for valve timing.

Additional Considerations with Timing Chains

While the longevity of timing chains is a major benefit, it does not mean that they are a perfect solution. Although a chain is not likely to break, it is more likely to stretch over time. As the timing chain stretches the valve timing changes, which eventually leads to decreased performance and fuel economy. Furthermore, because of the metal-to-metal contact inherent in a timing chain system, the sprockets will wear over time causing slop in the drive system. The chain sprockets may need to be replaced on high mileage engines. Overhead cam engines with timing chains will also require tensioners and guides that may require maintenance.

Timing System



Timing Belt

Less noise; inexpensive

More likely to fail if not maintained; material degrades over time, even when not in use

Timing Chain

Long lasting; less likely to break

Can stretch, reducing valve timing accuracy; sprockets can wear down, necessitating replacement

Both belt driven and chain driven systems are found in cars on the road today, and each has its benefits and drawbacks. Ultimately, it is most important for buyers to understand which system is present in their car, and to follow the manufacturer’s guidelines for maintaining the system.

Buying Timing Belts and Timing Chains on eBay Motors

You should first decide if you need a replacement kit or just the belt or chain. You can search the eBay Motors auction listings, and you can select the specific vehicle that the parts will be used in. Be sure to specify the correct year, make, model, and engine, since manufacturers sometimes make small changes to engines, even on similar cars. Check with the seller to ensure that the part is specified for your application. Top rated Sellers will be the most reliable source for these very specific parts. You can also check to see if other customers have left positive Feedback on a seller’s profile.

Choosing Between Aftermarket and OEM Parts on eBay Motors

Aftermarket parts sometimes offer cost savings over OEM parts. Some buyers will, however, want the added peace of mind of a timing belt or chain produced by the original manufacturer. In either case, you should never buy a used timing belt, and in most cases, you should not buy a used timing chain either. Try to find parts that are in the original packaging, since exposure to air over a period of time can prematurely age timing belts, and can lead to surface rust on timing chains.


While there are advantages and disadvantages to both timing belts and timing chains, the timing system is a very important maintenance area for all engines. For some engines, lack of maintenance can lead to serious engine damage, while in others a worn out timing system reduces engine efficiency and can cause a breakdown. The timing system should always be serviced at the manufacturer’s recommend mileage intervals. Used car buyers should always check the previous owner’s maintenance records to ensure that the service was performed. Current owners should check the owner’s manual for their car to determine the service interval, and be sure to complete the maintenance on schedule.

Both aftermarket and OEM parts are available on eBay Motors for a wide variety of vehicles. Car owners doing their own work should be sure to purchase any additional components needed for the job, such as gaskets and replacement tensioners or guides. Proper timing system maintenance will help to ensure long engine life, keep the engine running efficiently, and reduce the possibility of breakdowns.

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