How To Know When It's Time For Timing Belt Service

Timing belts are a part of what makes an engine tick. Made from neoprene or ethylene propylene diene monomer (EPDM) elastomer, timing belts allow the engine's crankshaft and camshaft to rotate in sync with one another. The synced motion allows the cylinders to fire in the correct order at the right time—hence the name "timing belts."

Like any other item, timing belts require replacement at regular intervals. But unlike a serpentine belt, the consequences for neglecting a timing belt change can be catastrophic. Knowing when it's time to change a timing belt is crucial for your vehicle's performance and longevity.

Consult Your Owner's Manual

The best way to know when it's time to change the timing belt is by checking the owner's manual or the scheduled maintenance guide that came with your vehicle. Either booklet should contain information about your vehicle's timing belt, including the recommended mileage intervals for changing your timing belt.

These intervals can vary depending on the year and model of your vehicle, as well as the type of engine it uses. For example, Toyota recommends that the timing belt on most of its vehicles be changed every 60,000 or 90,000 miles, depending on the engine used.

It's always a good idea to prepare for a timing belt replacement just before your vehicle reaches its recommended mileage. There's no need to panic if you've missed the mark by a few hundred miles. However, the longer you wait to have your timing belt replaced, the greater the danger of a sudden failure leaving you stranded on the side of the road.

Watch for Trouble Codes

A worn-out timing belt can have an effect on a surprising number of engine components. A deteriorating belt can cause other components to function improperly, resulting in poor engine performance and increased emissions. These conditions can get bad enough to trigger that dreaded "check engine" light on your dashboard.

When your vehicle triggers the "check engine" light, it also stores trouble codes that can be used to help mechanics diagnose and fix the underlying problem. If a "check engine" light appears, you should have an experienced mechanic check for trouble codes. A worn timing belt can cause the camshaft or crankshaft positioning sensor to set off one or more trouble codes, for instance.

Make a Visual Inspection

Unless you've installed aftermarket covers that leave the timing gears exposed, there's a good chance you won't see your timing belt until you remove its protective covers. Visually inspecting the timing belt in this manner isn't for the faint of heart, but it can give you a good idea of when to change the belt.

If you decide to visually check your timing belt, keep your eyes peeled for the following conditions. These conditions can also alert you to other problems involving your vehicle's camshafts.

  • Material loss - When you see entire chunks missing from any portion of the timing belt, it's a surefire sign that it needs a replacement as soon as possible.
  • Cracks and glazing - Just like serpentine belts, timing belts can also develop cracks due to aging, as well as a glazed finish on the top half of the belt due to extreme temperatures.
  • Worn edges - The edges of the timing belt can wear down due to misalignment of the pulleys or tensioners.
  • Excess slack - An excessive amount of slack in the timing belt could be due to stretching, although timing belt guide failure is also a common cause of excess slack.

When checking the timing belt, make sure the engine is turned off. Doing so will reduce the likelihood of serious injury during the inspection.

For more information, contact an auto service center such as a Toyota service center near you.