Timing Belt Replacement is extremely important. Your vehicle's timing belt is one of its most critical components and it requires regular maintenance and replacement in order for your car or truck to continue running smoothly. In fact, on nearly all modern cars, if the timing belt breaks, the engine will destroy itself. So paying attention to those regular intervals is vitally important.
Intervals for Timing Belt Replacement
Your vehicle's exact recommended timing belt replacement interval will be specified in your owner's manual. For most cars and light trucks, the interval is between 50,000 and 75,000 miles. On heavier vehicles, it may be closer to 100,000 miles. Do not ignore this interval - replacing a timing belt is expensive but letting it break will be catastrophic.
What the Timing Belt Does
The timing belt runs from the crankshaft at the bottom of the engine to the camshaft(s) at the top. In between, it usually turns the water pump and may also be responsible for powering the oil pump as well. The turn time between the crankshaft and the camshaft(s) is the engine's timing mechanism for knowing when a cylinder is compressing or decompressing and whether or not to inject fuel and send spark to the plug. Hence the title "timing belt."
When Timing Belt Replacement is needed
At the recommended interval, or whenever you happen to have any of the timing covers off so you can see all or part of the belt, the belt should be inspected. Whether it needs it or not, it's a good idea to get it replaced at the recommended interval in order to avoid possible problems.
Timing belt replacement is expensive, since much of the front of the motor must be removed (all accessories, all serpentine belts, and often the radiator and hoses). This major interval is a good time to replace other components that are now easier to get to as well.
Other repairs associated with timing belt replacement
Often, mechanics will recommend replacing the water pump, timing tensioner pulley, radiator hoses, etc. It's also a good idea to have the pulleys on each of the accessories checked (since they're off) to see if any are off-balance and need replacing. Especially those on the cam and crankshafts.
If your engine is in need of seal replacements at the exhaust or manifold heads, air intake, etc. now is also a good time to consider doing those.
Whether you do it yourself or pay a professional mechanic, you will find that timing belt replacement is expensive in both materials and labor. A competent mechanic should be able to do the timing belt on most vehicles in about five to six hours. A home mechanic can expect it to be a long day on the weekend.
The timing belt, however, is one of the most important mechanisms on your engine and should be cared for as recommended to avoid potentially fatal (to your car) problems later on.