The timing chain, especially when buying a used car, evokes several emotions at the same time. On the one hand, the steel, flexible element fuels a sense of confidence and reliability. While, on the other hand, it causes distrust and anxiety, running into expensive repairs.
Automotive technology does not stand still. The requirements for the efficiency of motors and their power are rapidly growing upwards. Entire systems and units are changing.
So unpopular earlier, the timing drive, in the form of a toothed belt, today is almost equal in reliability to a chain drive. Meanwhile, the "strong" chain is gradually losing ground.
The resource of the latter was significantly reduced in the era of the appearance of forced and turbo engines. Literally over the past 10-15 years, the concept of "half a million" for motors has become a thing of the past.
At the same time, the life of the chain mechanism has decreased from 350 to 150 thousand kilometers, while for the belt mechanism, on the contrary, it has increased to 120 (for some models up to 200 thousand kilometers)
Rating of the most vulnerable models
SsangYong Actyon- G20 gasoline engine, 2 liter displacement, 149 hp Applies this motor, just on korean SUV 2nd generation.
The well-known weakness place - drive Timing. The average chain resource is about 70 thousand kilometers. approximate cost replacement of about 20 thousand rubles, half of which are spare parts.
Skoda Octavia- we are talking about the second generation of A5. Applied 1.8 liter turbo engine, 152 hp. and torque 250 N.m. Good traction performance and high efficiency, turned into a low reliability of the chain element.
Most often, by a run of 65 thousand, car owners are faced with such a problem. The motor was also installed on Skoda Superb 2 generations and Yeti of the first version.
Suzuki Grand Vitara- compact japanese crossover and without that, is not particularly popular on Russian market. On top of that, in the design of the car, the manufacturer clearly does not use modern technologies.
So the chain, a two-liter gasoline unit, lives about 120 thousand km. There are two of them in the drive itself, so the repair cost will be more expensive. Also, don't forget the seal. crankshaft. Its leakage on this run is not uncommon.
Volkswagen Tiguan 1.4TSI- gasoline engine With mechanical supercharger and a turbine, just a storehouse of power. Its dynamic performance delights, and its high efficiency pleasantly warms the soul.
The question remains only whether a small motor, pumped up to 150 forces, can cope with such a load for a long time. Unfortunately no. The chain transmission simply “crumbles”, sometimes without having worked even 50 thousand kilometers. Not without reason, Volkswagen abandoned this motor in new generation Tiguana.
Peugeot 308 (1st generation)- a whole range of engines built on the basis of a 1.6 liter engine with the EP-6 index. Most often, there is an atmospheric version and a turbo version, with capacities of 120 and 150 hp. respectively.
All these related power plants, got general illness. Low chain resource. Basically, troubles occur on a run of 80-90 tons. Km. The engine was also installed on the Peugeot 3008, Citroen C3 Picasso and Citroen C4 models.
Skoda Fabia- a small and nimble car, from the Czech concern. The range of motors is extensive. Among which, the family with a working volume of 1.2 liters stands out.
These power units, have three cylinders and are famous for their high efficiency. The disadvantage is the same as the above cars. The limit of operation of the chain, about 90 thousand.
UAZ Patriot- Russian full SUV With carrier frame. Decent off-road potential and ease of repair, this is the main trump card of the Ulyanovsk all-terrain vehicle.
Weak spot in the timing drive, typical for all modifications gasoline engines ZMZ-409. The resource of the chain and tensioner is excessively small, about 35-50 thousand kilometers. It was also installed on the Hunter and the Cargo pickup.
In custody
Manufacturers stopped making eternal cars. Now they are more like disposables. As if after a certain mileage, you just need to throw it away and buy a new one.
Repair, too, "keeps pace" with the times. Instead of replacing one part, we are often forced to buy the entire assembly. Moreover, the design is such that the car owner has no choice.
Let's start with the history of the issue. In the early days of engines internal combustion the simplest and most logical was the camshaft drive using gears. It is necessary that the camshaft rotate twice as slowly as the crankshaft, and therefore two gears with a number of teeth related as 1: 2 were represented ideal solution. The gear drive circuit has the most high reliability. No wonder the famous T-34 tank was installed, which has not only a valve drive, but also all auxiliary units done with gears. Pre-war, and some post-war cars domestic production also had a timing gear drive with a lower camshaft.
On his chain!
Constructors automotive engines pretty quickly came to the conclusion that the place of the camshaft next to the valves. This solution simplifies the valve drive and reduces inertia, which is especially important for high-speed motors. And the distance between the camshaft and crankshaft has become quite large, especially on long-stroke engines. These are called motors, in which the piston stroke is larger than the diameter of the cylinder. By that time, bush-roller chains had already been mastered in production, which they began to use to drive camshafts. gear ratio provided a twofold difference in the number of teeth of the driving and driven gears. And the chains were used in two rows, for reliability.
For the first time in mass domestic engine chain drive appeared on, developed in the first half of the 60s of the last century. And soon the triumphant procession of the Zhiguli began, on which, until the beginning of the eighties, the camshaft chain drive reigned supreme.
I note that when using a chain drive, complex oscillations of the system always occur, caused by the uneven operation of the chain. To dampen these vibrations, minders have to install dampers in the form of plastic (sometimes rubber-coated steel) plates. In this case, the chain must be tensioned. This has to be done immediately after assembling the motor, and during operation due to the lengthening (drawing) of the chain.
Where does the "extraction" come from? Interest Ask. Of course, there can be no question of elongation under load of each individual plate that makes up the chain. Calculating the strength of these elements is easy. The elongation of the chain occurs with wear, an increase in the gap in each hinge, and there are usually more than a hundred of them. Accordingly, the total length of the chain can grow by several millimeters as it wears.
If this model the engine is not famous for its short chain resource (reviews on specialized forums will help you), then a chain drive is better than a belt drive. The belt drive can only withstand mileage up to scheduled replacement, and the chain can go longer. No wonder there is advice: buy used car- Immediately replace all belts, including timing.
I don’t want to offend anyone, but the owners of cars where the timing is driven by a chain look somewhat condescendingly at those who periodically think: “How is my belt doing there? ..”.
Tell us in the comments what type of timing drive you like and why.
Many car buyers are often faced with such concepts that are often encountered among motorists as “timing chain” or “timing belt”.
For those who already have some experience in operating a car, the meaning of these terms usually does not raise questions.
From this article you will learn:
However, the widespread availability of the car and high level the convenience of its use entails the appearance of everything more people who have little idea of what a “timing mechanism” is and what advantages a chain or belt has for its operation.
In order not to fall for the bait of servicemen, who often offer to pay for work that they did not perform, you need to have at least general idea about how the engine works and why it needs a chain or belt.
How the timing mechanism works
Timing - gas distribution mechanism. With the help of this mechanism, fuel mixed with air enters the engine and the gases resulting from combustion are removed (clearly visible in the moving picture).
The fuel-air mixture enters the cylinders through intake valves(valves) that open at a certain point in time. After the combustion of the mixture, the resulting gases are removed through the exhaust valves, which also open at a certain point in time. Special camshafts (Camshafts) are responsible for opening and closing the valves at a certain point in time.
Most modern engines, installed mainly on cheap cars, have two camshafts located on top and actuating the valves. This type of engine has the abbreviation DOHC - Double Over Head Camshaft.
To ensure the rotation of these camshafts V various models motors use a special drive with a belt or with a chain (Timing belt).
The condition of the timing belt (or chain) must be constantly monitored, since the possibility of further operation of the engine depends on the correct operation of the entire timing mechanism.
When a belt (or chain) breaks - a fairly common failure with improper engine care - on most modern engines, the pistons "meet" the valves. After such a "meeting" the engine will need overhaul, which is very expensive.
Pros and cons of the timing chain mechanism
The main and main plus of the chain in the timing mechanism is its durability. On some engine models, the chain can serve for a very long time - about 300-500 thousand kilometers without requiring any action from the owner, except for inspection for deviations in operation.
Engines with a timing chain drive are very much appreciated by taxi drivers, car owners who have very big runs and people who prefer to spend as little time and money on a car as possible.
As for the disadvantages of the timing chain, most experts point out the noise of the operation of such a mechanism, which often greatly interferes with recognizing other “unhealthy” engine sounds that can lead to its breakdown.
Also, the disadvantages of the timing chain mechanism include the complexity and rather high cost of replacing it (when reaching maximum mileage, or, in rare cases, an open circuit).
Pros and cons of the timing mechanism with a belt
The advantages of the timing belt drive mechanism include its very low noise level, the engine with the belt is noticeably quieter than the engine with the chain.
However, this fact can be appreciated mainly by car service masters, since on most modern cars there is good sound insulation of the engine compartment and the car owner will not feel the difference in the noise of the chain and belt engines.
Also, the advantages of the belt include the relatively low cost of replacing it (in comparison with the chain).
As for the cons of the belt, there are much more of them than the pros.
The main disadvantage is the low belt life. On most cars, the timing belt “walks” no more than 100 thousand km (there is also a replacement period every 80, 60 or even 40 thousand km).
When the timing belt has reached the end of its service life, it must be replaced. The procedure is quite complicated, it is best to go through it in a specialized service, since the service life of the engine will directly depend on the quality of the work performed.
For each car model, the timing belt replacement procedure has its own cost (about 10-20 thousand rubles), which increases the total cost of operating the car.
Many other problems follow from the need to regularly change the timing belt for the owner of a car with such a mechanism.
For example, the owner needs to find a place where they sell quality spare parts(prices official dealer does not suit everyone) and good service, where they will make a quality replacement. The owner also needs to constantly monitor the timing of belt replacement so that they do not exceed the maximum.
Another problem for a potential car owner can be with a timing belt. Not all sellers can say for sure when the belt was last changed (some people forget, while others try to hide it in this way). real mileage cars).
What to buy and how to choose?
Based on the reliability and cost of operating the machine, the timing chain drive is, of course, preferable.
However, before making a choice, a potential buyer needs to find out which engines are generally installed on the selected machine.
It often happens that the selected car has no alternative at all - all the engines of the selected car have a chain, or vice versa - all the engines of the selected car have a belt.
For every motorist, the choice of a future car is a combination of all kinds of pluses and minuses. The design of the timing mechanism in this set cannot be decisive, it can only add one plus or one minus.
In internal combustion, gasoline and diesel engines, the camshaft is located at the top of the cylinder head. The classic timing design provides for the transfer of rotational force from the crankshaft to the camshaft through a chain drive. The timing chain drive has a number of advantages and its own specific disadvantages.
History of the timing chain drive
The chain drive has a fairly long history. The mass use of the chain (as well as the timing belt) refers to the end, that is, by the time of the transition to a design with an overhead camshaft.
The main disadvantage of the chain is noisy operation. The main advantage is durability
Recently, toothed chains have become more widespread, gradually replacing roller chains. They have greater flexibility and advantages that are more characteristic of a belt drive, the main of which is low level noise at work.
Chain drive design
Typically, single and double row roller chains are used for the drive. They carry out the transfer of force from the sprocket, mounted on, to another sprocket, put on the end of the camshaft.
The chain has practically zero ability to stretch and compress, and rather limited flexibility. Therefore, in order to provide it with a constant tension during operation, it is necessary to use powerful hydraulic tensioners, similar to miniature oil ones. There can be from one to three such tensioners, depending on the number of camshafts.
In order for the chain to "sit" in its place at any speed, it has to be literally shackled, surrounded by a system of tensioners and dampers
Even a well-tensioned chain retains the ability to "play" in those places where there are no sprockets or tensioners. The chain is a design that develops large inertia, so the chain drive requires vibration damping. This problem is solved by dampers - additional spring-loaded clamping bars. They have a steel frame covered with a layer of durable rubber. The dampers are equipped with weak springs that allow the chain to "play", but only to a limited extent. Tensioners and dampers effectively dampen vibration and noise. The chain is prevented from falling off by a restrictive pin that is screwed into the block or. At normal operation the chain does not touch it.
Advantages of Timing Chain Drive
The performance and durability of the timing chain drive depends on the material and quality of the heat treatment of the chain itself and the sprockets.
Precision manufacturing and cleanliness of work surfaces are of great importance. The main advantage of the timing chain drive is its durability. On modern engines chain resource is from 100 to 200 thousand kilometers. If high-quality materials were used in the manufacture of components, and during operation they provided correct tension, then the chain will last no less than the engine itself.
Circuit breakage is rare. The deterioration of its condition can be tracked by increased noise during engine operation.
Disadvantages of timing chain drive
Of course, a timing chain drive is more complicated, and therefore more expensive than a belt drive. However, chain drive reliability is often more important than higher cost.
The chain is an attribute of expensive and powerful motors requiring special care for the reliability of the design
The main disadvantage of the chain is its inaccessibility. The chain drive requires a constant supply of oil, so the mechanism is usually located inside the cylinder block (and, partially, inside the cylinder head). The chain is practically not subject to wear, which cannot be said about the shoes (damper) and hydraulic tensioners. Even for visual inspection of these elements, not to mention the replacement, you have to disassemble half of the engine.
The disadvantages of the timing chain drive, in addition to cost and complexity, include noise during operation, more weight. But despite these shortcomings, it is the chain drive that is used in the motors most prestigious cars- Jaguar, Mercedes, BMW and others. This is explained by the desire of manufacturers to provide expensive, but reliable equipment.
Hard to believe: Last year about 40% of complaints about cars were related to ... timing chains. Our readers began to complain about them much more often. For comparison, the same timing belt is less frequently complained about: we encountered complaints about it in 28% of letters. It's funny, but unlike the one that is subject to periodic replacement, it is the chains that are designed for an extended service life.Why do timing chains cause so many problems?
Automakers order almost all parts from contractors. But both are trying to cut costs. Therefore, costing and reducing production costs are as important as production itself. You have to save on development, materials, technological processes. Ultimately, such savings affect quality.
When to expect a problem?
Trouble comes too soon. Still fresh in my mind is the timing chain report. TSI motors(on VW concern cars), when, according to our data, problems appeared already at 20,000 km or even less. On average, a timing failure occurred at a range of 40,000 to 60,000 km. Everything used to be much better: old double chains (for example, motors Mercedes W123) served forever, and simple single chains easily survived the "age" of 200,000 km.
Are there any symptoms of an upcoming problem?
Eat. A running engine makes unusual sounds, reminiscent of "knocking / crackling / rattling". At first, they can be heard when the engine is running cold, right after the morning start. When the chain stretches or skips significantly, the dashboard lights up" check engine". You need to immediately go to the service station, otherwise the engine can simply be ruined.
Who will pay for repairs?
If a breakdown occurs during the warranty period, then the repair should be free of charge for the customer. However, trouble with the timing chain can also occur when guarantee period ended. In this case, manufacturers offer the client to pay part of the cost of work and spare parts. But in order for the manufacturer to meet halfway, you need to provide complete history proper vehicle maintenance.
What manufacturers are doing to prevent such breakdowns?
Actions depend on what caused the breakdown. BMW 116i and 2.2-liter engines Diesel Opel received improved chain tensioners. The VW concern changed the chains, because. the problem was the quality of their manufacture. Many of the newest engines again have timing belts, but the interval between their replacements has been increased to 200,000 km.
Letters about these cars come to the "complaint box" of AUTO BILD magazine
What causes problems with the timing chain
This is how a 4-stroke engine works: fuel and air are mixed in the combustion chamber. Piston ( 1) compresses the mixture, then it ignites, doing work and pushing the piston down, after which the piston rises again, pushing the combustion products through exhaust valves(if there are several). Then all 4 measures are repeated. But in order to synchronize the movements of the piston with the opening and closing of the valves, you need a chain (2) connecting camshaft (3) And crankshaft (4) . If the chain stretches or jumps over a tooth, opening the valves (5) and the movement of the pistons ceases to be synchronous. In the worst case, the valves (inlet or outlet) will start to open when the piston reaches the top dead center. In this case, the piston will hit the valves: the result of this is shown in the photo.
In addition, the connecting rod may bend (6) hit piston. In any case, the engine will receive serious internal mechanical damage. The sectional drawing shows a 2-litre diesel bmw engine, which has one feature: the timing chains, of which it has two, are located on its rear end, from the flywheel and clutch side. This means that replacing chains will take a very long time and be expensive. for this operation, the motor will have to be removed from the engine compartment.
MY ADVICE
If you're looking to buy one of those used cars pictured above, try to collect as many as you can. more information about service. Stretching or jumping the timing chain will result in a costly repair. Especially in the case of the 2-liter BMW diesel. A used car must have a completed book with a proper service history. But the most ideal option: when in this very book the fact of eliminating this characteristic problem is noted. If the problem with the timing chain shows up on a non-warranty car and the engine is damaged, then it will be cheaper to buy and install a "used" unit than to repair your own.
Bernd Volkens
