What is a timing belt and when should I change it?
The engine of a car is made up of elements essential to its operation, such as the crankshaft and the camshafts which must be properly aligned. This alignment must be perfectly achieved from the mounting of the timing belt when it is changed.
Those drivers who do not repair the car on their own have little idea of the structure of the modern car as a whole and in particular the gas distribution mechanism. They have no idea – what is the timing belt, and what functions are assigned to it.
Any engine is a structurally complex unit that instantly responds to all inconsistencies in the operation of the mechanisms and components associated with it. Its maximum accuracy depends on the synchronous rotation of the crankshaft and camshaft, but there will be no synchronized operation if the torque from one node is not transmitted to another using a drive.
Two of the most common types of drives are known – chain and belt, while the belt drive is easier to maintain, and is used to transmit torque most often. The standard timing belt through the pulleys (gears), rollers, tensioners, connects the belt drive as a whole, ensuring the transmission of torque from the crankshaft to the camshaft at the time of engine start.
The timing belt can also be connected to the coolant pump pulley, but some automakers use a conventional drive belt to operate the pump, which greatly simplifies the design of the drive.
The classic timing belt is a toothed belt with internal teeth having the highest possible precision in casting. The shape of the profile of the teeth can be of three types – trapezoidal, rounded and mixed type of profile. The trapezoidal shape of the tooth is considered classical, but the round one is used when increased operational capabilities of the drive belt are required to transmit large torques. The mixed type combines the operational capabilities of the two previous types, but in practice it is used very rarely.
The belt necessarily has a power frame (cord base), which is necessary to prevent premature stretching during intensive work.
To maintain the longitudinal stability of the drive belt, fiberglass is used to make the cord, and the sheath of the belt, in which the cord threads are located, is made of synthetic neoprene rubber. Thus, it protects the cord from premature wear, which provokes a break in the belt.
At the same time, the belt is not initially monolithic – the teeth, which are also made of neoprene, are welded to the belt shell, and the high precision of the casting guarantees uninterrupted transmission of torque, and optimal “adhesion” between the belt and tensioner rollers.
Leading manufacturers of auto parts in the manufacture of a timing belt can use other, no less durable materials.
The resource of any components and consumables was laid down by the manufacturer initially, but not every manufacturer displays this. In the case of the timing belt, its service life depends on the quality of the material from which the consumable is made, and the timing belt is a consumable. And if the manufacturer does not indicate how long it should be replaced, such information should be displayed in the technical documentation for the vehicle. If the timing belt issue doesn’t get solved then the easiest way would be just to sell your car for companies that offers cash for scrap cars service.
- On average, the vehicle mileage recommended for replacing the timing belt should not exceed the mark of 90 – 100 thousand km, in particular, this applies to both old used and many new foreign cars.
- On modern machines, especially Japanese and German production, the replacement period can be shifted to 120 – 150 thousand km, but it is recommended to regularly check the condition of the belt drive and with visible signs of critical wear, do not wait for a break, but change it immediately.
- There are also such car models on which the resource of the timing belt can be within 200 thousand kilometres, but this, in turn, does not apply to the tensioning equipment (rollers) of the belt drive. Their resource, no matter how high quality they are, does not exceed the limit of 120 thousand km, and changing rollers without replacing the belt is impractical and dangerous.
- It is recommended that the belt be replaced even if the machine is purchased on the secondary market, and the former owner cannot tell the exact date of replacement of the belt drive components.