Issues addressed in the material:
- How to understand that the timing belt has broken
- What to do if the timing belt breaks on the go
- Avoiding premature timing belt breakage
Some vehicle owners do not pay enough attention to the timing belt, but only when its too late. In the best case, damage to it can cause the car to not be able to start. Next, you will learn what to do if the timing belt is torn, and how to avoid this.
The first signs of a broken timing belt
Many of those who own the vehicle are faced with the question of what to do if the timing belt is torn. For novice drivers, the topic of this breakdown belongs to the category of horror stories that are the cause of rumors, most of which are at variance with reality.
The timing (gas distribution mechanism) is driven by a crankshaft gear. Previously used timing belts and chains, which became widespread about 20 years ago, aroused mistrust among car owners.
Compared to the chain mechanism, the belt drive is a simpler design, it weighs less and does not work as noisy. However, it also has disadvantages, the main of which is the small resource of the timing belt.
The question of what to do if the timing belt is torn arises when there are signs of damage, which are that the vehicle begins to stall, after which it cannot be started. If an attempt is made to turn on the ignition, a metallic knock appears, the cause of which is the impact of the pistons on the valves. It is worth noting that a breakdown can cause a rather serious problem: at high speed – this is a guaranteed failure of the valves, which will have to be changed. If we talk about the worst consequences, this is damage to the pistons, gaskets and pastels.
The signs suggesting that the timing belt has broken and something needs to be done should include the following:
- the motor stalls suddenly;
- it is impossible to start a car;
- there was a metal knock at the top of the engine when the starter was working (pistons hit the valves).
However, before looking for an answer to the question of what to do if the timing belt is torn, you need to make sure that a break has indeed occurred by looking under the hood of the car. You will see a torn timing belt and its damaged casing.
As for the chain drive, it has a fairly long service life. If the motor is not “forced”, the chain can last more than 200 thousand kilometers. Over time, it begins to stretch and rattle, which indicates the need for its replacement. If we talk about a high-quality belt, then it is able to last about 60 thousand kilometers, after which it is changed, even if it is not damaged in appearance. If this is not done in a timely manner, a break can occur.
Causes of Timing Belt Break
The timing belt connects the crankshaft and camshaft. In addition, thanks to it, the valves in the engine are opened in a timely manner, as a result of which the required amount of the fuel mixture enters the cylinders.
Since the timing belt can break only when the vehicle is in motion, it is easy to determine this failure. The car engine stalls, which may require a major overhaul.
Reasons why the timing belt may break:
- Wear. Since this element is of great importance, only the most durable materials are used for its manufacture. The term of its operation in this case is about 150 thousand kilometers. If you do not replace it in a timely manner, the timing belt may break.In addition, it is worth considering that some vehicles have a shorter shelf life, so it is advisable to do diagnostics every 15 thousand kilometers. On average, replacement is necessary every 80-140 thousand kilometers. However, you should first of all adhere to the manufacturer’s recommendations.
However, in practice, if the unit is serviceable (generator, pulleys, pump in order), then the belt can last about 100 thousand kilometers. But at the same time, do not forget that a lot depends on who the manufacturer is.
- Desynchronization of tension rollers. Thanks to these elements, the belt is tensioned, which prevents it from flying off the teeth. If you do not change them on time, this will lead to premature abrasion. The cause may be jamming of the pump.
- Poor quality spare parts. Manufacturers, especially when it comes to European, Japanese and American brands, install only high-quality parts. Therefore, if, after wear, instead of using cheaper analogues, they can quickly break, causing damage to the belt.Often there is a situation when the timing belt breaks after 5,000 kilometers. As a rule, saving on the purchase of this consumable leads to very sad consequences. If we compare the difference in the price of a quality and low-quality product with global consequences that may arise, then this ratio is in-commensurable.
- Faulty pulleys, shafts, tensioners. If one of these nodes fails, the timing belt breaks. Therefore, manufacturers, as a rule, recommend changing the tensioner rollers with it.
- Insufficient or excessive belt tension. Incorrect adjustment of the tension leads to the same consequences as malfunctions of the units. For example, if the tension is weak, the timing belt slips due to insufficient adhesion to the working surface of the pulley, so it overheats, loses elasticity and begins to collapse. Otherwise, stretching and further rupture of the reinforcing fibers occurs. Understand that with the tension of the timing belt something is wrong, it is possible by a characteristic whistle. Most often, this happens in wet weather.
Sometimes the belt does not break, but the teeth wear out, as a result of which it ceases to fulfill its functions.
What happens when the timing belt breaks
The consequences of a timing belt break are affected by the design of the power unit.
In order to understand what will happen in this case, you need to understand the mechanics of the internal combustion engine.
When the engine is running, the pistons continuously move from one dead center to another. At the time of the intake stroke, the piston moves downward and the intake valve opens, during the release, the exhaust valve opens and the piston moves upward. When it is at top dead center, the valves should all be closed.
When the belt breaks, the camshaft stops and the valves are fixed in one position. At this time, the crankshaft continues to move by inertia, and the pistons rush towards the valves that are open.
It is worth noting that some engines, for example, the 8-valve VAZ-2111, have recesses designed specifically to avoid contact with the valves in the event of a break. This helps to get rid of the consequences, except that the car simply can not get to the workshop or garage.
The design of modern multi-valve motors is designed in such a way as to obtain maximum power with a small volume, so the pistons do not have such grooves or they do not have enough depth. In this case, if the timing belt breaks, this will certainly lead to the meeting of the pistons and valves, as a result of which the latter will bend.
If it broke at idle, most often only a few valves are bent, if it happened in the gear at high speeds, the whole set will have to be changed.
The greater the crankshaft speed at the time of the cliff, the worse the consequences. In addition to the bending of the valves, the guide bushings may burst, and this in turn leads to the replacement of the cylinder block and its head. In addition, the impact often causes the destruction of the pistons.
There were cases when, at a break at high speed, all valves were bent from an impact, the head of the block was damaged, the guide bushings burst, and fragments from them pierced through the pistons. It is worth noting that in such cases, engine repair is very expensive. According to statistics, such damage is most often received by Japanese twin-shaft (DOHC) engines.
If we compare gasoline engines with diesel engines, for the first, the consequences of the timing belt breaking are lighter. Their design is arranged in such a way that the valves have virtually no free play when the piston is in TDC.
In this case, if the belt breaks, the following occurs:
- bend the valve;
- the camshaft with bearings is destroyed;
- the head of the unit fails;
- pushers and rods bend.
When a break occurs at high speeds, the pistons may collapse and the cylinder block may be damaged.
Since this problem is quite common, manufacturers began to make recesses at the top of the piston, which are aimed at preventing “jamming” of moving parts. If the timing belt is torn on the road, then just need to be replaced.
What to do if the timing belt is torn
If the question arose about what to do if the timing belt broke, then:
- Open the engine compartment, raise or remove the protective cover of the mechanism.
- Assess the appearance of the belt. If it is torn, then it will certainly be seen. In the case when the cliff occurs below, to detect it, you need to scroll the crankshaft half a turn.
- Then, using towing, the vehicle must be delivered to the garage or to the service station. With an automatic transmission, a tow truck cannot be dispensed with, since towing in the case of such vehicles is not at all permissible.
In addition to the attendant details, you will need to buy:
- A new timing belt or repair kit with a bypass and a tension roller.
- Gaskets for the manifold (intake and exhaust).
- Valve covers and gaskets for cylinder head.
- A set of bolts for fastening.
- The pump is suspected of wear.
If the timing belt is torn, it is easiest to replace it on the lift. This will require the following tools:
- keys set;
- timing pins for timing marks;
- special tool if necessary.
When dismantling, you must proceed according to the following plan:
- Remove the cover that is fastened with bolts.
- Remove crankcase bolts.
- Remove the compressor and put the belt back in place.
- Remove the alternator belt.
- Remove the terminal from the battery, thereby disconnecting the contacts.
- Unscrew the fasteners from the engine, remove the generator, terminal, as well as the pump pulley, before unscrewing the bolts that hold them.
- If necessary, remove engine mount.
- Remove the cover protecting the timing belt.