What is a Timing Belt?

Machines are just fascinating. And how they work is even more, isn't it? The other day, when I saw a mechanic repairing a car, the urge inside me to know more about the working of an engine and other car parts made me learn something interesting about this particular part called the timing belt. So what is a timing belt, after all? Well, it is a belt, as the name suggests, but there is more to it. It is a belt which is placed in the internal combustion engine of a car, which controls the timing of the valves of the internal combustion engine. So if anything goes wrong with this timing belt, the engine won't work.

Working Mechanism of Timing Belt

The purpose of an internal combustion engine in a car is to convert the chemical energy stored in the battery into mechanical energy. The mechanical energy is generated when the pistons of the combustion engine are set into motion due to the fuel combustion. The linear motion which causes this mechanical energy is factored by the rotational motion (also called torque) of the crankshaft that is connected to the pistons of the combustion engine. For every 2 revolutions of the crankshaft, the camshaft rotates once.The valves in the combustion chamber open up when the engine is set on. The air-fuel mixture is let in every piston cycle. The camshaft which is connected to the crankshaft through this timing belt, controls the valve opening thereby controlling the piston motion. Now this piston motion is sustained by the timing belt, which helps in synchronizing the camshaft and the crankshaft, for the smooth functioning of the engine. If the timing belt snaps, the camshaft will stop rotating thereby leaving the valves in open position. The crankshaft, being the heavier part is kept in rotation under inertia. Hence if the engine is of interference kind, the pistons will keep striking the open valves, leading to broken valves, a damaged cylinder head or a damaged piston.

Indications of a Dysfunctional Timing Belt

So if there is any malfunctioning with this timing belt, efficiency of the combustion engine can be compromised. Now that we know what is a timing belt, let's figure out some timing belt problems which can be harmful to your car engine.

• A Heated Engine: If your engine abruptly stops working and the engine is heated up intensely, then it may attribute to high temperatures and following problems like oil leaks. Hence if the engine breaks down abruptly and refuses to start after repeated attempts, make it a point to check for a broken timing belt. In a case, where the belt has snapped, the best and the only option is replacing a timing belt. Many manufacturers suggest a timing belt replacement once in 4 years, when a car completes at least 60,000 miles.
• Too much Exhaust: If your car is emitting too much of exhaust smoke, there is a possibility that the timing belt has got damaged. It is best to diagnose symptoms as early as possible, because if your engine is interference type, it might cost you a fortune in getting the repair done.
• Refusing to Start: If your car refuses to start on a regular basis, the problem may be due to a timing belt gone bad. There is a lot of ambiguity connected to the situation as many car problems have this symptom. Further, if the engine makes unusual noise too along with this car starting problem, the timing belt should be checked at the earliest.

However it depends on the kind of engine which is used in the car. If it is an interference engine design, then the damage to the timing belt can be severe. This can be caused by if the valves and the piston strike against each other, causing the timing belt to snap. A serious valve train failure or a 180 degree timing error can factor this condition. However, if the engine is of non interference type, the motor will simply stop, while there is a small gap between the valve and the piston which keeps them from sliding against each other. Nowadays, the timing belt is made up of rubber belt which is quite unlike the steel timing chain (which can last approximately 150,000 - 200,000 miles and more). Timing belts are mostly used in small and medium-sized passenger cars like 1993-97 Toyota Corolla, 98-01 Honda Accord and 2001-04 Volkswagen Passat.

Timing belt replacement is very important for sustaining a longer engine life and must be done as soon as your car covers about 50000-70000 miles. But when it comes to costs incurred for replacement, for different cars, the timing belt replacement cost differs depending on whether the engine is interference or non interference type. In case of interference engine type, where there is no space between the valve and the piston, a bad timing belt can cause the whole of the engine to get replaced. Timing belt replacement cost depends upon the engine make and the car make as well. Most of the time, the cost to replace timing belt ranges between USD 250-750, which is inclusive of the labor cost that is fixed per hour. And remember, replacing a timing belt must be done only by an experienced mechanic. Keep checking for any unusual symptoms as mentioned above and maintain your car in a good shape with timely replacement of timing belt.