AThe rubber timing belt is part of most internal combustion engines and is responsible for synchronizing the engine’s functions. It controls the rotation of the camshaft and crankshaft and the opening and closing of the engine’s many valves to allow air and gas in and out, which causes the fuel to ignite in the combustion chamber. During this explosion, the valves push the pistons down.
“In order for the process to take place, the valves have to open and close at the right time,” Roberson says. “The valves have to be in the correct position as well as the pistons. The valves open at different times for each cylinder. It’s a mechanical ballet of sorts.”
When the timing belt breaks, the valves, which are very light, will open at the wrong time and hit the larger pistons and cause damage.
Unfortunately, in most cases, there are no obvious signs the timing belt is near death; it will just break. That’s why highly rated auto mechanics recommend replacing it every 60,000 to 100,000 miles. Always check your owner’s manual for the manufacturer’s recommendations.
Timing belts used to be a relatively ignored maintenance item by many drivers. Roberson says replacing a broken timing belt used to be common, but now he says most replacement jobs are for preventive maintenance.
“People are a lot more aware of the timing belt, and the mechanics are educating drivers more about them,” Roberson says. “Now, more people know about it and what can happen when it breaks.”
Replacing a timing belt for preventive reasons typically costs $400 to $900. However, replacing a broken timing belt may cost up to $2,000 or more if it caused damage to the valves, pistons or water pump.
