Timing belt replacement: the harsh truth

Gas distribution mechanism - a special part of the car. It requires attention rarely, but if the driver overlooked, there will be a lot of trouble. The timing will not only fail, but it will also harm neighboring systems. About the secrets and truths of the timing drive service tells the master inspector STO Bosch Service Alexander Melnik. We give his answers to the most common questions about the belt and the theme of “oppression-oppression”.

Respecting the belt was taught to me by veteran race drivers, experienced mechanics of the old school. “The main thing in the engine is the“ head ”with the camshaft and valves, they said, it decides everything. And the piston - nonsense, blanks. Since that time, in the device of the internal combustion engine, if something has changed, it is only in the direction of the reinforcement of this old-regime theory.

The gas distribution mechanism and its drive can be arranged either to tears primitively, or incredibly abstrusely, but almost always it will have a belt. Probably everyone knows that it can break - and then the owner's heart stops with trepidation: will it bend or not? But even without a cliff there are very unpleasant cases - sometimes incomprehensible and mysterious.

What is it bending?

Valves bend, not always, but often. In the upper part of the cylinder of the modern engine is very close - there are two or four valves, a candle, often a nozzle, a low head arching due to the high compression ratio. And it is worth only the valve "hesitate" in the open position, like a piston, rising to its top dead center, reaches it. In the worst case, the valve stem bends, the guide bushing deforms, the valve jams in the open position, the piston is damaged or destroyed by hitting it, fragments crush the walls of the cylinder - and the engine is sent to the overhaul or landfill. At best (if I may say so), the valve only bends, sometimes the engine even works, although it is unstable and with an unusual sound.

Why is it breaking?

The timing belt is terminated primarily due to wear. But there are other reasons for trouble - for example, the incorrect operation of the guide and tension rollers in the drive. The roller can rotate with a bias, which causes uneven - and therefore premature - belt wear. One of the frequent causes of a sudden failure of the belt is jamming of the roller. Moreover, for many engines, such a roller serves as a pulley for driving the cooling system pump, which can jam due to the destruction of the bearing of the pump itself.

And if it does not break?

Actually, a cliff as such may not be present - and on a completely fresh one, and on an old, honestly served out belt, it can simply cut off one or two teeth. This happens when abnormal loads - for example, the old belt can not withstand cold start on a frosty morning, and starting a frozen engine from a tug (especially diesel engines) can ruin a new belt. The most insidious case when, due to incorrect actions of the driver, the already “tired” belt jumps over one or two teeth on the pulleys. The timing is shifted, the engine can not operate normally in principle, but there are no external signs of a timing failure. Because of this, some car owners are repairing fuel equipment, changing piston rings, sensors, ignition modules - instead of going to a good service station with competent specialists and checking the marks on the timing pulleys.

Why not?

Modern cars do not forgive rudeness and unqualified treatment. Therefore, experts at Bosch Service recommend that in case of “abnormal” situations, seek competent assistance from the service station and not act in the old manner. If the car does not start naturally - by pressing a button or turning the key, do not pull it on the cable with another car. Because in many cases it ends with a cliff, skipping, bending - and a complete disassembly of the engine. The timing belt must not be operated beyond the mileage indicated by the automaker. In domestic conditions it is better to reduce the service life of those belts, which are prescribed to replace 120 thousand km - up to 100 thousand km. Naturally, the quality of components timing can not be saved.

What do you need?

Given the long period between replacing the timing belt with each routine replacement, it is more reasonable to change all other consumables and components involved in the drive - guide rollers, tensioners, pump. Even if at the time of replacement of the belt, they still do not show signs of critical wear, it is likely that they will fail before the next scheduled replacement of the belt - and then an open or “jumping” of the teeth is not excluded.

As a rule, car manufacturers, along with the replacement of the timing belt, recommend changing the cooling system pump. Postponed replacement of the pump is a gift of money spent. In some modern cars, the cost of replacing parts may be two to three times the cost of the pump itself. In addition, the client has to visit the service station twice and spend extra time. “Bosch Service” always ensures that the client receives a comprehensive service for servicing the timing drive.

“Do not forget about the timing drive of your engine, because it can give the car owner serious trouble. But he will never remind himself if during scheduled THAT everything is done according to the instructions and with the mind. Actually, this can be said about any of the systems of the modern car ”─ summarizes Alexander Melnik.