Timing belts are a critical but often overlooked part of your car’s engine. When an engine is not correctly timed, it will run poorly and inefficiently. If the timing belt breaks in an interference engine, the engine may suffer extensive damage. The pistons will crash into the valves, breaking the valves, bending the rods and possibly causing damage to the pistons.
Timing belts connect the crankshaft to the camshaft and drive the camshaft. The belt provides the timing for piston motion to correct valve opening and closing. In non-interference, or free running, design engines, belt breakage will not normally cause engine damage. In these engines, there is enough clearance in the engine to prevent contact between the valves and pistons. Timing belts may also power other mechanical parts including the water or oil pump.
Timing chains:
Timing chains were used on older cars and would generally last the life of the vehicle. It was a rare occurrence to hear someone say that they had broken or slipped their timing chain. Timing chain problems were more likely to occur in vehicles used for racing than everyday road use. Normally engine failure would cause the chain to break instead of belt failure causing the engine to break. It may make you wonder why the chains are no longer used in most vehicles.
- Timing chains were heavy; manufacturers are reducing vehicle weight to improve gas mileage.
- Timing chains could be noisy, consumers wanted quieter interiors.
- Timing chains were more expensive; a rubber belt reduced the costs in manufacturing and purchase price.
When it comes to newer vehicles that use timing chains, failures can occur due to tensioner problems. The chains are longer in Double Overhead Cam (DOHC) engines and use a series of tensioners and guides that can fail and require costly replacement. Proper lubrication is also required to prevent binding.
Timing belts and replacement:
Always follow the vehicle manufacturer’s recommendation when it comes to belt replacement and additional suggested services. If the water pump is located under the timing belt, and the belt needs to be removed to replace the pump, replace the pump at the same time the belt is changed. If the water pump has been changed recently, this step can be skipped. Otherwise, you may face the need to replace the timing belt again if the water pump fails, well before the belt would otherwise require replacement.
Timing belts should not be removed from the vehicle and then reinstalled unless there is very little mileage on them. Once the belt has been in use for any length of time, it will stretch and really should not be reused. Average belt prices run from $20 to $60 dollars. Some brands of belts are good for up to 100,000 miles. Spend a little extra and get the best quality.
Timing belt replacement intervals vary by the car manufacturer and the type of belt installed. Vehicles built after 1999 may have recommendations of up to 100,000 miles between belt changes. For vehicles built before 1999, most manufacturers recommend a belt change at 60,000 miles. Some of these vehicles include:
- Volkswagen
- Toyota
- General Motors
- Subaru
- Mazda
- Honda, but 2.3 liter engines and above range from 75,000 to 105,000 miles.
- Ford, but 2.5 liter 6 cylinder engines should be changed at 30,000 and 2.0 Single Overhead Cam (SOHC) gas engines can run to 100,000 miles.
BMW and Nissan, most models, are manufacturers that still use timing chains. Honda, GM and Ford are using timing chains in some vehicle engines.
Timing belt tips:
- If you purchase a used vehicle, try to get information on when the timing belt was changed, if it ever was.
- Invest in the best quality, longest lasting timing belt for your vehicle. It is the labor that is costly. The belt is only a small portion of the total cost. This also applies to do-it-yourself enthusiasts.
- If your engine has an internal oil or antifreeze leak, have the belt inspected when repairs are made. Oil and antifreeze can damage the material and shorten the belt’s life span.
