Timing belts have replaced timing chains on many of today’s engines.
Not to be confused with “V-belts” or “Serpentine belts”, which are located on the outside of the motor to drive accessories, timing belts perform a much more vital role.
The purpose of a timing belt is to provide a connection between the camshaft and crankshaft to ensure that the pistons and valves operate together in proper sequence. Timing belts have proven to be lighter, quieter and more efficient than chains, but those benefits come at a cost – they require more frequent replacement than chains.
The 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. 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 valves open at the same time the pistons are at the top of the cylinder, your engine can suffer anything from bent valves to a broken piston. You will have to disassemble the top part of the engine before you know the full extent of the damage.
There are two types of engines that use timing belts. Free-running and interference are the names we use.
If the timing belt breaks on a “free-running” design, the engine will stop and you will need a tow to the repair shop. There is enough clearance between the pistons and valves so no mechanical damage usually occurs. Consequently replacing the timing belt may fix your problem.
If the timing belt breaks on an “interference engine”, mechanical engine damage will occur. Most commonly, the damage involves the pistons hitting open valves, resulting in the need for expensive repairs. In extreme cases, replacing the engine may be required.
Breakage is not the only reason to replace your timing belt. Looseness and wear can allow the timing belt to slip, resulting in very poor performance, a no-start condition, or engine damage.
Proper maintenance requires timing belt replacement at regular intervals – before it breaks or wears out. The manufacturers provide a replacement schedule and repair information for this critical component.