A toothed belt has several advantages over a chain. It is clearly more expensive. Making a belt is much easier than making a chain. By and large, this is a closed belt made of oil and petrol resistant rubber, reinforced with nylon cord with teeth pyrvulcanized to it. If we compare it with a chain, then the comparison will not be in favor of the latter. The belt is much lighter than the chain, which, of course, cannot but affect the mass of the engine. In addition, a belt-equipped engine is much quieter than its chain-equipped counterpart. And mounted "rubber" outside the engine cover, which affects the time of its installation or replacement. For example, the author of these lines takes 25-30 minutes to replace the timing belt and then install it according to the marks. With a chain, such a trick will not work.
With proper maintenance and control, the toothed belt runs for a long time. Domestic manufacturers, recall, give a guarantee for a mileage of 60 thousand km, foreign - and even more. Rover managed to push back the belt replacement period to 160,000.
What is the correct control and maintenance of this simple device? At least every 15-30 thousand km, the correct position and tension of the belt should be checked. However, this does not mean that it is only necessary to move the casing back and check if the belt is in place. It is best to inspect it by removing it from the engine. Sometimes it is difficult to notice that one of the teeth has broken. If this has already happened, then be sure that he will not last. Therefore, having removed the belt, make a mark on it with chalk, and then tooth by tooth "drive away" his. After installation, it is also necessary to check the position of the guides and tensioner. All these elements must be on the same axial, otherwise the belt will work with a warp, which will not benefit it.
An important factor for the operation of the belt is the absence of oil on its surface. Whatever the oil and petrol resistant rubber from which the belt is made, it is still not the case when "you can't spoil porridge with butter". This is where oil comes in handy. Therefore, periodically it is necessary to pay attention to the condition of the seals. And if you already notice an oil leak, try to fix it as soon as possible. As practice shows, the presence of a belt in an oily environment reduces its resource by half, or even three times.
If this control is ignored, the consequences will not be long in coming. After 40–50 thousand km, by pulling the belt, the required tension weakens and it begins to whip. As a result, the heavy camshaft does not rotate synchronously, but lags behind. This asynchronous operation of the motor leads to an even greater weakening of the belt. As a result, there are excessive loads on the teeth.
Breaking several teeth in a row can lead to the fact that at one point the camshaft will remain stationary while the knee will rotate. It is at such moments that the open valves meet the pistons. The result is a broken or bent valve, its broken bushings, a broken camshaft. There are, however, exceptions when the cliff is almost painless. However, this is only possible on those vehicles in which there are grooves in the pistons specifically for this case. These, for example, include our VAZs, namely cars with engines VAZ-2105, 1300 cm3, and VAZ-2108, 1500 cm3.
If the car is not equipped with such an engine, a broken belt costs the owner a tidy sum associated with engine overhaul. The cost, for example, of a belt on a BMW reaches $40. Repair of the same engine on the same Saab will cost $5,000. For VAZ "nines" The belt can be purchased for $25. But the repair of the engine will pull on $400.