Timing belt

Timing belt

Timing belt

According to Iskanews economic group, one of the main parts used in car production is the timing belt. In general, the timing belt is the part of the internal combustion engine that manages the timing of the engine valves. In other words, the timing belt is a type of plastic belt that is placed inside the engine and in the cylinder head of the car.

Also, it is an interface between the car’s crankshaft and the valve shaft.

The main task of the timing is to rotate the valves and control their opening and closing time. So that with every two rotations of the crankshaft, the valve shaft rotates once. By connecting the car’s crankshaft to the valve shaft by the timing belt, the four main actions of the engine such as suction, compression, power and discharge are carried out.

The history of the use and design of timing belts in cars

The history of using belts in the production of cars goes back to the 1960s. For the first time in 1962, the German car manufacturer Glass 1004 used a timing belt. Then in 1966, a car engine was produced by the Pontiac company that used a belt instead of a timing chain for the first time in America. got a job

How the timing belt works in the car

Internal combustion engines go through four stages to start the car. In the following, we recount the mentioned four stages.

Suction stage: In this stage, the piston inside the cylinder goes down and causes the air valve to open. This function causes fuel and air to mix inside the cylinder.

Compression stage: As the piston rises inside the cylinder, the air valve closes, which compresses the fuel and air mixture.

Power stage: the spark plug sparks and the compressed mixture explodes. Now the piston is down and the smoke valve opens.

Discharge stage: Next, the piston rises again and the smoke exits the valve.

The timing for opening and closing the air valve and the smoke valve in the above four stages is formed by the timing belt. This piece adjusts the opening and closing time of the valves by coordinating the rotation speed of the crankshaft with the valve shaft.

Timing chains and timing belts

In the early years, car manufacturing companies used timing chains to adjust valve shaft timing.

The lifetime of the timing chain is much longer compared to the timing belt; Because the belt is made of rubber and must be replaced at the right time, but the chain is made of iron, so it wears less but costs more and makes a lot of noise. In heavy and old cars, timing chains are used instead of timing belts.

In addition, if the timing chain is broken, the damage it causes to the engine will be very large, and in some cases it may be necessary to replace the entire engine. Another difference between belt and chain is their location. The timing belt is installed inside the engine, but the timing chain is outside the engine. Also, because the chain is metal, it needs oiling, while the belt should never be soaked in engine oil.

Among domestic cars, timing chain is used only in Pikan and Pikan van production. Of course, some modern car companies use timing chains in the production of their cars to control the sound of the chain and because of its high resistance. For example, since 2006, Toyota, Benz and BMW companies have been using timing chains in the production of their products.

Signs of timing belt friction

Failure to start the car

As we stated at the beginning of the article, The main function of the timing is to adjust the valve shaft and crankshaft. As a result, when the belt is worn, the timing cycle is disrupted and causes the car to not start properly.

Erosion of teeth

If the timing belt is not replaced at the right time, it will cause erosion and corrosion of the gears over time.


When the timing belt is worn or loose, the car’s engine has to work harder to move its parts, resulting in a lot of stress. The applied pressure causes the smoke to come out of the exhaust.

The amount of engine speed

When the timing belt has a problem, when the car accelerates, the engine speed increases more than usual and the engine power decreases. So it starts to slip. This function can indicate the loss of teeth.

In addition to the mentioned cases, signs such as incomplete ignition and turning on the check engine light are also signs of belt friction. Timing belt replacement depends on the performance and operation of the car.

Causes of timing belt failure

There are many reasons that reduce the lifespan of the timing belt, which we can prevent from causing problems and damages by following them.

Fluids: Getting the belt stained with engine oil, antifreeze and grease causes it to loosen and tear.

This issue is very important because oil leakage, in addition to causing damage to the belt, causes the car temperature to rise and the engine to boil.

Non-standard: Be very careful when buying a belt. If the belt does not have a standard tension; Over time, it loosens and is released from its original place. As a result, it leads to wear of the ribs.

Misadjustment: If the belt ribs are not positioned correctly, they collide and rub when the car is turned on, which eventually causes the belt to stretch, crack and tear. Applying pressure: when excessive load is applied to the belt, it loses its efficiency over time and breaks. Signs of excessive pressure applied to the belt include the creation of small and large cracks, corrosion. He pointed out the teeth and the stretching of the timing belt.

Damage to other devices: When replacing the timing belt, replace parts such as the idler and water pump. Because the damage of these parts also damages the timing belt.

Problems caused by timing belt tearing

If you do not replace the timing  on time, it may break. When the belt breaks, the most pressure and damage is applied to the valves. In fact, according to the adjustment by the belt, the valves and pistons do not collide with each other, but if the belt breaks, this balance will be disturbed and the valves and pistons will collide with each other.

A broken belt causes a lot of damage to the car and its engine. The amount of damage caused to cars varies. For example, in old Prides, a broken belt only causes the car to shut down and cause serious damage to the engine. It does not import. This is despite the fact that in Peugeot 206 and Peugeot 405, the torn belt leads to collision of piston and valves, and as a result, it causes the valves to tilt.

Alternator belt

The useful life of the alternator belt is much less than that of the timing belt. In other words, after traveling 20,000 kilometers, the alternator belt is worn out and has friction. If you don’t replace it, the worn and torn pieces will go into the timing chamber and cause the timing belt to break.

The best time to change the timing belt

Most car manufacturing companies have specified times for changing the timing  in their catalogs.

The best period for changing the car’s timing belt is 6 years after production or in other words after traveling 60 to 120 thousand kilometers. Of course, you should note that this number varies in different cars.

In some cases, it is possible that the car’s timing will break earlier than the prescribed time based on the navigation, so you should consider the time intervals for replacement and check it frequently.

Below is a list of the best time to change the timing belt of different cars:

Thunder 90: 40 thousand kilometers

Megan: 60 thousand kilometers

Rio: 65 thousand kilometers

Xantia: 65 thousand km

Peugeot 405: 70 thousand kilometers

Mazda 323: 70 thousand kilometers

Toyota Corolla (model 2005 to 2012): 90 thousand kilometers

Pride: 100 thousand km.

It is recommended to change the timing belt when changing the belt. It is true that the service life of the bearing is longer than that of the belt and it needs to be replaced after every 100,000 kilometers, but it is better to know that the damage caused by the damage of the bearing, such as the damage of the timing belt, causes many problems.

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