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When Does My Timing Belt Need to Be Replaced?

when to replace a timing beltWhen it comes to your engine, timing is everything. Even a microsecond can throw the engine’s combustion process off. Luckily, your car is equipped with a timing belt or chain to make sure everyone is on time, even if you’re not. A timing belt is what controls the camshafts in the engine to open and close valves at the right time for smooth operation. Most people are unsure when to change their timing belt. To start, the timing belt has grooves that turn the camshaft in time with the crankshaft. Crankshafts rotate at half the speed of a camshaft. Two revolutions of the crankshaft are equal to one revolution of the camshaft. 

Timing belts aren’t one-trick ponies though. They also drive other components including the water pump, balance shaft, intermediate shaft, injection pump, and the oil pump. To work effectively, a timing belt must have a certain amount of tension controlled by the timing belt tensioner. In older cars, these tensioners would need adjustment if the timing belt became loose, but modern vehicles are equipped with an automatic timing belt tensioner that does not require adjustment. If the timing belt gets loose, it may skip a tooth causing the timing to fall out of normal range. 

Timing Belt vs. Timing Chain

Some cars or trucks use a timing chain which is more durable but requires oil to prevent metal on metal friction. Timing belts are made of rubber and quieter but do wear out over time. A timing chain can last as long as the engine and seldom requires replacement. 

When to Change the Timing Belt

Most timing belts are meant to last between 60,000 – 90,000 miles, your owner’s manual will recommend the ideal timeframe for replacement in your vehicle. However, keep in mind that in Arizona our dry, hot climate may claim the life of your timing belt long before it’s recommended. Err on the side of sooner rather than later.

When It’s Time for a Timing Belt Replacement

The timing belt is located under a timing cover at the front of the engine. Have the belt inspected often or do so yourself looking for any damage such as cracks, divots, oil saturation from the engine, or other indications of wear. If not replaced the timing belt can break which is bad news. If the timing belt breaks, the engine won’t run. When timing belts fail, the camshaft stops turning causing valves to stay open when they shouldn’t. Meanwhile, the crankshaft continues rotating, which allows the pistons to keep moving up and down, causing them to collide with the open valves, damaging engine components including bent or broken valves, damaged pistons, damaged cylinder heads, and the cylinder block. 

Symptoms of a Bad Timing Belt

  • Car Won’t Start – If the timing belt has become detached or is otherwise broken, the vehicle will not be able to start. If the timing belt detaches while the engine is running, there is a risk of internal damage. 
  • Rough Idling – Intake and exhaust valves are unable to open and close at the proper time causing misfires or difficulty accelerating as well as cause the engine to shake as the belt slips. 
  • Misfires – The combustion rate could be threatened from a worn belt. If a timing belt slips from the gears and falls onto the camshaft, the cylinders won’t be able to open and close at the proper time.
  • Check Engine Light On – A failed timing belt may trigger the check engine light to come on due to the change in performance from increased emissions. 

Timing Belt Replacement Cost

The average cost of a timing belt replacement can range between $250 – $700, however, this number can vary based on the size, make, model, and year of your vehicle. While the cost of the belt itself is not too high, the labor required to replace the belt is quite intensive and some vehicles may make gaining access to it more difficult than others. 

It’s a good idea to replace the water pump around the same time you replace the timing belt since they’re in the same area. Though you will need to pay a bit more for the water pump, you’ll save on the additional labor costs than if you replaced it at a later date.