Carmakers have specified the replacement intervals for timing belts every 50-70,000 miles.

In an interference engine, the valves and piston share the same air space. They never touch, unless your timing belt breaks or skips, and this is a catastrophic failure that requires removing the head and replacing bent valves. Non-interference engines do not risk this contact if the timing belt goes. Nonetheless, can leave you stranded, so regular timing belt replacement is very important

In your motor, timing is everything. That's why your timing chain or timing belt are so vital to the operation of your entire vehicle. You see, without a properly installed and adjusted timing chain or timing belt, the valves on your engine don't open and close at the appropriate times. A sloppy timing chain can result in poor running, valve clatter, and loss of power, while a broken timing belt can cause your engine to stop running or, on an interference application, cause your valves to crash into your pistons. If that sounds expensive to you, you're right.  While a timing chain may last the life of an engine, a timing belt has specific requirements for replacement intervals.  Check your owner's manual for timing belt replacement mileage and follow those requirements to the T. If you have a timing chain instead of a timing belt, signs that your timing chain may need replacement include loss of power and noise from the timing cover at the front of your engine.