Every time before buying a car, we think about what engine size it has, how many “horses” are under the hood, what fuel consumption is, we compare the car by color, interior trim, and various exterior elements. Of course, these issues are important, but no less important is such a parameter as the timing belt drive, in short, the timing belt.
Reference!
The timing belt is an engine element that serves as a connecting link between the crankshaft and camshaft on any modern car.
Renault Logan engine options
Let's consider the option that you are going to purchase the beloved people's car, Renault Logan. The designers of the Renault concern equipped the cars (except for the top-end configuration) with two types of engines, which passed all kinds of technical tests and have the indexes K7J, K7M, which indicates engines with a volume of 1.4 and 1.6 liters 8V (valves), respectively. And the LUX class car has a 1.6-liter engine with a 16-valve “head” with the index K4M. In each of them, a belt acts as a drive for the gas distribution mechanism. And about which engine to choose in the material:
Now let's look at each engine separately and figure out which of them will bend the valves if the timing belt breaks.
K7J – 8-valve engine with a volume of 1.4 liters (valve bending)
The most popular engine among domestic consumers bends valves
The four-stroke four-cylinder gasoline engine K7J has evolved in our time straight from the 80s of the 20th century. Due to the fact that the motor is a continuation of the line of engines of the previous generation, it has a clearly prominent feature in the form of an outdated design with increased consumption fuel. However, this does not prevent it from remaining one of the most maintainable engines in the line.
On this engine There are no hydraulic compensators, so every 15-25 thousand kilometers it requires a valve adjustment procedure. And periodically oil leaks occur at the crankshaft oil seal.
Bent 3 valves out of 4
Some Logan drivers prefer the more powerful K7M version to this engine.
K7M – 8-valve engine with a volume of 1.6 liters (valve bending)
A less popular 1.6-liter 8-valve engine is the K7M.
The K7M engine from Renault is practically no different structurally from its predecessor K7J. , the same liquid cooling and combined lubrication system. The same problem of oil leakage and lack of hydraulic compensators remains - we adjust the valves.
Bent valve
However, if you look at specifications, then this engine has a 10.5 mm increased piston stroke (due to the fact that the block height is changed), as well as the largest engine volume and flywheel.
However, all the above-mentioned advantages did not help in any way to save the engine valves; when the timing belt breaks, they bend.
K4M – 16-valve engine with a volume of 1.6 liters (valve bending)
Bent valve on K4M engine
A distinctive feature of this “top” engine from the previous ones is two lightweight camshafts in the cylinder head and a new piston system. As a result, the power increased by 20 hp compared to the K7M, while efficiency and operational stability increased. On the K4M engine there is no problem with adjusting the valves after a certain mileage interval, since the above-mentioned hydraulic compensators are already present there.
The timing drive is still carried out using a belt and bends the valves in the same way as on previous engines when it breaks.
Causes!
The timing belt can break for various reasons.
From all of the above, we understood that on all types of Renault Logan car engines, when the timing belt breaks, the valves bend. And below we will describe the reasons why breaks occur in general and how to avoid it.
- Timing belt wear (poor quality or technical wear), oil ingress, etc.
- Various foreign bodies getting under the belt
- Pump jams
- Tension roller(s) jam or loosen
- The crankshaft or camshaft is stuck
In order not to worry about the condition of the timing belt, you must constantly monitor its external condition, the degree of tension, replace it according to the regulations or change it immediately if there is any damage to it. Make sure that oil and other liquids do not come into contact with the belt (this will cause premature wear).
This was once a piston and part of an engine
If, when the timing belt breaks, only the valves are bent, we can say that this is great luck. In some situations, such a breakdown may damage the pistons themselves and the surfaces of the cylinders.
Symptoms and behavior of the car that require replacing the timing belt
As a result of increased loads or wear of the connecting rod and piston group, the timing belt may jump one turn, resulting in... This phenomenon is a symptom of checking the condition of the belt and its correct installation.
Repair cost
Specifically in each situation, depending on the condition of the engine, after it stops due to a broken timing drive, auto mechanics will calculate the cost of repairs strictly individually.
Considering the usual example of a broken belt in a K7J engine, the average cost of repair (including materials) will be approximately 10-15 thousand rubles.
Welcome, friends, to the DIY auto repair website. Experienced car enthusiasts know that a broken timing belt can lead to dire consequences. In particular, there is a high risk of “meeting” valves that have already come out of their seats and pistons rising by inertia.
The result is deformation of vital engine elements, as well as an urgent need to visit a service station and carry out major repairs. But does the valve always bend when the timing belt breaks? Should we be afraid of this?
There are so-called non-interfering engines, in which valves and pistons will not collide and where a belt break will have no more effect than a new timing setting. The drive belts have two sides. The inner gear is the one that drags the elements that need to be perfectly synchronized. The outer surface is smooth, and on this surface are supported tension rollers, which force the belt to undergo, and other elements, such as the water pump, which do not need absolute synchronization.
A little history
The new “tens” were immediately equipped with 8-valve engines with volumes of 1.5 and 1.6 liters. The first power units (from the perspective of the problem we are describing) were ideal, and the valves did not bend. Although earlier models like eight and nine with a volume of 1.3 had this problem. The reason was that the piston structurally could not “meet” the valves.
The timing belt is an optional preventative maintenance item, although changes will take longer over time and will be one of the most expensive vehicle maintenance items. Respect for time is important to avoid belt failure, which deteriorates over time.
There are a number of conditions that make it advisable to pay more attention to the condition of timing belts and, if necessary, change them at an early stage. For example, those who make a lot of short trips and in the city should take special care, as should those who live in extreme climates, or park a car on the street or move in very dusty, rainy or dirty environments.
Over time, a more modern VAZ 2112 model appeared in the “ten” family, equipped with a one and a half liter engine with a 16-valve engine. It was from this moment that the problems began. Many car enthusiasts and specialists could not understand why the valve bends.
In fact, the reason was in the design of the power unit. On the one hand, the appearance of a 16-valve head made it possible to increase the car’s power to 92 “horses,” and on the other, a broken timing belt invariably led to a collision of pistons and valves, as well as deformation of the latter.
When replacing a belt, it is important not to waste or replace all the peripheral components. So we have to change all the tensioners and the water pump if it is driven by a belt. It is also recommended to replace the camshaft and crankshaft seals to avoid possible leakage due to deteriorating camshafts in the future. In the case of countershaft shafts, the drive belts and the necessary bearings also need to be replaced.
After that, I had to go to a service station and have the car undergo expensive repairs. The design fault lay with the pistons themselves, which lacked the necessary recess. As a result, the timing belt break always ended in the same way.
Updated car engine
A similar oversight was taken into account and more advanced 16-valve 1.6-liter engines were installed on new VAZ 2112 cars. Structurally, the power units were not very different, but one feature was still present. In the new engine, the pistons had certain recesses, so the problem described above was eliminated.
Bypassing these items could mean that someone has defects post hoc, which would imply reimbursement for all the labor, which is the most expensive part of replacing a timing belt. Removing and assembling a timing belt is a complex task and should preferably be carried out by specialized personnel. This requires some know-how and the appropriate tools. Failure to follow the steps correctly can result in breakdowns and breakdowns that can easily reach all four digits.
Mechanical valve problems begin to occur when the engine is subject to overheating, lack of lubrication, or over-torque. Bent valves not only damage pistons, but also valve guides, camshafts, and camshaft components. If your engine's drive belt breaks while driving, severe damage to the internal engine can occur. This is especially true if your vehicle is equipped with an interference engine. Interference motors have tight tolerances between valves and piston caps.
Over the next few years, car enthusiasts began to forget about bent valves and became accustomed to the reliability of the new 16-valve engines. But the updated Priora model with a 1.6-liter power unit was an unpleasant surprise - the valves also bent when the timing belt broke.
At the same time, the final repairs were much more expensive. On the other hand, the developers made the belt as wide as possible to minimize the likelihood of the belt breaking. The only unlucky ones were those car enthusiasts who received a defective belt or those who did not take care of their “iron horse” at all.
Engine overspeed
Once the timing belt is damaged, the engine continues to rotate long enough for the pistons and valves to touch. Damage may include bent valves, broken pistons and damaged engine heads. Depending on the engine your vehicle is equipped with, there is a maximum RPM that your engine can safely run. When the maximum RPM is exceeded even for a short time, engine damage can occur, including bent valves.
Unfortunately, even on the new 1.4-liter Kalina engines with 16 valves, repairs cannot be avoided if the belt breaks while driving. So monitoring the state of this node is mandatory.
On which VAZ engines does the valve bend, and on which ones does not?
Let’s draw intermediate conclusions and also highlight the most “dangerous” and “safe” models from the perspective of probable valve deformation in the event of belt damage:
When the engine accelerates excessively, the valves can "stretch" and come into contact with the pistons. When overspeeded, the engine cannot maintain proper timing and allows the valves to contact the top of the pistons and cause severe damage to the piston and valves to flex.
Problems such as lack of lubrication and engine overheating can also cause bent valves. If you continue to run the engine while it is overheating, the engine's internal tolerances are reduced to the point that the valves can stick to the valve guides, causing the valves to contact the pistons. Likewise, when there is insufficient lubrication, it can cause the valves to stick to the guides, causing the valve to bend when it hits the pistons. In engines with overload valves, lack of lubrication and overheating can cause the lifters to stick, resulting in two bent valves and bent lifters.
1. Which VAZ engines bend valves? This category includes car engines of the following model range - 21127, 21116, 2112, 1194.
2. Which VAZ engines do not bend valves? More reliable are the engines of such VAZ models as 1183, 21114, 21083, 21124, 21126 (they bent until 2013, but now they don’t), 21128.
The current problem has caused a lot of controversy among car enthusiasts. Many owners of “problem” VAZs are interested in what to do to prevent the valve from bending. In fact, there are several recommendations.
When rebuilding an engine, care must be taken to ensure that proper clearance is provided between the pistons and valves to ensure that the valve reliefs on the piston caps are properly aligned with the intake and exhaust valves. Be careful when milling the heads to ensure that the valve is supported in the direction of the piston. Specification for lifting the control valve before assembling the exhaust valve. If any of these specifications are incorrect, you may cause bent valves when the engine is first rebuilt.
Find out that a modern car has several hoses that can stick or clog and even a terrible pressure when opening the gas cap. Previously, a carbureted car needed one hose to feed the engine, but nowadays the engine requires at least two, and any defect in them can cause your car to fail, stall, or even consume more fuel at its best. leaks. The tank is an example of this issue as it clearly shows the existence of most hoses and their fundamental functions for good engine performance and allowing gases that were previously released into the environment.
They are as follows:
1. First, try to periodically assess the condition of the timing belt and replace it at the first sign of damage. The appearance of cracks, contact with engine oil on the surface, excessive stretching, peeling of the edges - all this is a reason to install a new timing belt and not wait for a break.
2. Secondly, if engine repairs are expected, then you can change the pistons, and in some cases, the crankshaft. In addition, some experts recommend (as a solution) installing a new camshaft.
The main hose is the fuel pressure line that takes the pressurized fuel to the groove that feeds the injector jets, but pay attention to the filter that stays on that line and its maintenance because if it gets clogged, the fuel won't reach the pressure and flow correctly into the nozzles. In addition, it is important to evaluate the general condition of the pressure hose for possible folds or wrinkles that impede the flow of fuel, but we cannot help but point out possible leaks that often occur even inside the tank, since there is a small hose that directs the fuel collected by the electric pump, onto the cap, and that very often cracks or leaks are found in the clamps, which ultimately create a loss of pressure in the system.
But here, of course, you can’t do without consulting specialists. After this, flashing and removal of the catalyst may be necessary.
If you get a car with bent valves, then don’t despair ahead of time. The ideal solution would be maximum attention to the engine and more frequent timing belt replacement. Even this will be enough to minimize risks.
When there is a loss of the required pressure for the engine to operate properly, the vehicle may fail or deteriorate, fuel consumption will be high due to low pressure, since the electronic injection module will have more injectors, and at low pressure, the fuel flow will be changed and poorly controlled.
The return hose is responsible for the unnecessary engine starting fuel that is released by the throttle body, but be careful as this regulator also has a screen that can become dirty and this can prevent the fuel from flowing properly and create a defect in the system. Fuel feedback has been used in the past to increase fuel pressure in unofficial methods that allowed a gasoline engine to run on alcohol, and it is always worth checking to see if there is an external component in the return hose that was used for this function, or even if For some reason the hose is not bent or obstructed.
As for replacing components and expensive repairs, these costs, as a rule, are not justified. Good luck on the roads and of course no breakdowns.
Often the phrases flash in the conversations of car enthusiasts: “I got in for repairs, the belt broke, the valves were bent.” Of course, in such cases we are talking about the timing belt. In order to understand the causes of the “catastrophe”, let us consider in general terms the interaction of the connecting rod-piston group and the gas distribution mechanism.
The returning fuel is routed to the pump bowl or housing so there is no shortage of fuel to the last drop within the system, but unfortunately the pump bowl or reservoir is not handled very well by some unsuspecting professionals who may break or not care about its proper assembly. which can allow the lack of fuel with low levels or curves because the fuel can roll and the pump traps air instead of fuel.
The most common fuel leak occurs at the fuel pump assembly seal, especially after replacing the primer pump due to the common practice of not replacing the pump liner, which can allow a leak when the tank is filled to the maximum or even a persistent smell of fuel that is exhaled by the pump seal. Fuel couplings on the pump cover are also often abused when moved and are always evaluated.
This interaction is strictly coordinated, otherwise normal operation of the engine cannot be ensured.
Operating principle of the valve-piston system
Let's take the compression stroke as an example. When the piston, compressing the combustible mixture, approaches top dead center, it comes almost close to the combustion chamber (on diesel engines, to the surface of the head). If at this moment any of the valves are not closed, then loss of compression will be the lesser evil. Most likely, the valve, the rod of which is rigidly held by the rocker arm (or camshaft cam) from above, will take the impact of the piston.
The gases absorbed by the container will be burned by the engine, and this process is controlled by the injection module, which controls the valve that allows these gases to be absorbed by the engine. Fuel supply hoses, which direct fuel from a bottleneck into the reservoir, are victims of drying and road objects that often get thrown around the wheel and require a visual inspection whenever vehicle is being reviewed or when the smell of fuel is detected.
A strong fuel odor can also come from the fuel cap or its bottleneck, since this cap is not indestructible, therefore timeless, since it is one of the busiest components due to reserves. The cap seal is in most cases located in the neck itself, and this neck can break or the rubber seal fails. The fuel cap still needs to be replaced, allowing fuel to evaporate through the key entry slot, and this is very common.
The valve bends in the event of a collision between the valve and the piston
In very rare cases, the manufacturer provides recesses in the piston crown to avoid collision. From what has been said, I hope it is clear why the valve bends when the timing belt breaks: the camshaft stops rotating, some of the valves remain in the open position, being a “convenient target” for pistons moving by inertia.
Now that you know the function and major drawbacks of fuel lines, it's interesting that you talk to your mechanic about reviews to evaluate these important components. Existence had brought us there at this moment, now it depended on us to look and understand. He came to the end of the laboratory visits, even those that had been reserved earlier, in the days when he was working on earthquakes with other laboratory machines. We were there for two days, but he stayed there after we left. In general, from a phone call later, we realized that we had been working on it for almost a week.
The coherence of the timing with the crank mechanism is ensured by the precise installation of gears or sprockets. To do this, installation marks are made on them and on certain points of the engine.
According to the type of torque transmission, the gas distribution mechanism drive can be:
- Belt
- Chained
- Geared
Let's look at their common malfunctions, which can lead to bending of the valves.
Timing drive device
Consequences of a broken timing belt
Some inquisitive motorists are interested in the question: is it possible to bend the valves with a starter? The answer is easy! Just do not install sprockets or gears “at the marks” - and the key is to start! Once the engine starts, you will immediately learn to recognize the symptoms of bent valves. Although, if you don’t “miss” too much, then everything can be corrected by assembling the timing drive according to the rules.
If just one valve is bent, the engine will run rough. Even if it is a V-shaped “six”, you will hear it.
If, after restoring the camshaft drive, the engine runs smoothly and develops the same power, then you are lucky and the manufacturer prudently supplied the pistons with sufficient recesses in the bottoms. But, unfortunately, this is not always possible. First of all, when designing a motor, the designer strives to combine many seemingly contradictory qualities of his “brainchild”. For example, such as efficiency and power. This may, to some extent, justify the fact that on 16-valve engines the valves often bend when the timing belt breaks.
Such problems are especially acute for creators diesel engines, in which compression and the necessary swirl of the fuel mixture determine the power characteristics. Therefore, the combustion chamber is located in the piston bottom and often has a whimsical shape.
However, behind this lies the precise calculation and modeling of vortex flows on a computer. Such chambers are called undivided and making recesses for the valves is impractical from the point of view of high-quality atomization and maximum efficient combustion of the fuel mixture. The piston is almost close to the head of the block. Therefore, it is not yet known for certain whether there are diesel engines on which “the valves do not bend.” Although, perhaps, human genius coped with this disaster.
Repair
Bent car engine valves
Never try to repair bent valves in any way!
Replacement, and only replacement!
If you straighten the valve “by eye”, you risk getting yourself into even more trouble. A valve restored by hand is unlikely to be aligned with the guide bushing and will press tightly against the seat. And if you want to straighten the rod “a little”, it will work like a pump, pumping oil into the combustion chamber - no cap will hold it.
It would be prudent to troubleshoot other parts as thoroughly as possible. After all, an impact can damage guide bushings and valve seats. There are known cases when connecting rods were bent. Breakage of rocker arms is also not uncommon.
Models of VAZ engines whose valves are not “afraid” of timing belt breakage:
VAZ 2111 1.5l; VAZ 21083 1.5l; VAZ 11183 1.6l (8 valve); VAZ 2114 1.5l and 1.6l (both 8 valve)
It is known that old 8-valve Opel engines (such as those on the DAEWOO Nexia and Chevrolet Lanos) also calmly endure this trouble.
As a rule, if a person has bent at least one valve on his favorite car, even just once, such a person already begins to understand that even “hardware” does not have iron patience and will try to become a good owner of his “horse”.
In conclusion, it would be useful to add - keep an eye on your car, do not doubt whether there is a reason to “look under the hood”.
The automotive industry knows of thousands of engine options that are not very pleasant to operate. In particular, on such power units, when the timing belt breaks, the valves bend and meet the pistons in a chaotic inertial stroke. Bent valves will have to be treated by replacing them, as well as rebuilding the entire upper part of the engine. This will cost the owner of even an inexpensive domestic car more than 15,000 rubles. Therefore, if such an opportunity exists, it is better to choose power units in which the valves do not bend when the belt breaks. Today we will look at domestic developments in the field of automobile engines. It turns out that in this regard, the engines on domestic cars were quite adequate. Many of them did not know such a problem as bent valves for various problems.
AvtoVAZ generally designed quite interesting power units. Yes, most of them did not have much potential and consumed a lot of fuel. But in reality it turned out that the engines did not require any maintenance at all. They simply served for years without causing any problems or negative situations. In many units, they didn’t even change the oil, filling once with 30-40 thousand cheap mineral water, which they could get in the days Soviet Union. So there is no point in criticizing the engines of the first VAZ models, up to the VAZ 2108 and 2109. It turns out it was best time domestic auto industry, which showed maximum potential and a minimum of problems in use.
VAZ engines from 2101 to 2106
Often in older cars, VAZ used maximum simple technologies. The developments of the 70s of the last century actually served until recently, because the latest version 2106 was discontinued just a few years ago. It is very interesting that the entire range of these cars had engines that received a lot important advantages in operation:
- power units often had 8 valves, as well as places for folding them in case of problems;
- the timing belt or chain was of quite high quality, lasted 50-60 thousand kilometers (or more than 200 in the case of a chain);
- the engines operated in all weather conditions without problems and received a lot of positive feedback from experts;
- some export cars have become popular in very civilized countries of the world.
At the time of development of each of the VAZ cars in the 2101 - 2106 range, the transport was simply amazingly good. Even today, after 40 years from the release of some models, you can find them on secondary market cars with engines that never bend valves, and the power unit is not afraid of other problems. These are the features of old VAZ designs.
VAZ 2107 engines with timing chain
Most VAZ 2107 power units, including all the latest engine modifications, had special timing chains that serve quite adequately and do not fail for years. You can drive about 200-250 thousand kilometers on one chain, then replace it simply because the motorist’s conscience begins to remind you of maintenance.
It is important to remember that if the chain begins to make some unpleasant sounds, it should be changed at that very moment. But even if the chain will break, most modifications of the VAZ 2107 engine will not cause the valves to bend. Therefore, the owner of this car can be completely calm about the safety of his car’s engine.
VAZ 2108 and VAZ 2109 - a whole era in Russian cars
Hatchbacks, which were popularly called “Chisels”, gained fame as reliable and durable cars, they were produced until our time, assembled in Ukraine for several years, but have completely lost their relevance appearance and technology. Today you can buy on the secondary market great option"Nines" are quite recent year of manufacture in perfect condition. The engine in this car has the following features:
- In the history of the model there were 1.1, 1.3 and 1.5 liter power units with a carburetor, as well as a 1.5 liter injection unit;
- all engines were protected from the influence of timing belt rupture, the valves in the power unit did not bend;
- the car had quite adequate engine reliability - this unit was the last one to break down in the car;
- All presented competitors at one time were distinguished by their advanced design, excellent comfort and other benefits.
At the very beginning of their production, VAZ 2109 and 2108 cars were a real revolution in the domestic automotive industry. Buyers of such cars have become real lucky ones in the eyes of their acquaintances and friends, exactly the same as buyers of the latest Mercedes models today. And there were certain logical reasons for this, such as the incredible reliability of the main components.
VAZ 2110 - “Tenth” family and new problems
“Tens” appeared in the VAZ model line quite a long time ago, but they gained popularity in 1998. Ten years later they were discontinued, giving way to new domestically developed products. Today, the “Ten” is considered a completely adequate vehicle with certain assembly problems. These models had different engines and had different characteristics:
- The 1.5-liter 8-valve simple power unit did not bend the valves, but showed only 72 horsepower;
- a modified 1.5-liter engine with 16 valves began to actively bend these same valves;
- a more modern 1.6-liter power unit in an 8-valve design should have been gentler, but it didn’t;
- You also won’t get cheap repairs after a broken timing belt on the most powerful 1.6-liter 16-valve VAZ 2110 engine.
The entire family of “Tenth” models was of quite high quality and reliable, but the further the plant tried to keep up with power, modernity and relevance, the more trouble the car got into. The most durable and high-quality engine was the 1.5 engine with 8 valves and 72 horses, but latest models with powerful 16-valve units we encountered only problems, judging by the reviews of car owners.
The modern era of VAZ engines - the main problems
For Lada Kalina was slightly modified the lineup power units. This car was the first in the new generation VAZ family to have all engines that bend valves when the timing belt breaks. Also Lada Granta received three types of power units that actively bend valves. All budget VAZ power units in modern design have bent valves. Priora and Largus offer the following types of engines:
- the base engine of the Priora is a 98-horsepower power unit, the only one that spares valves in the modern VAZ model line;
- the second power unit has the same design, but 106 horses, and these extra 8 horses will cause the valves to bend;
- The 1.6-liter engine with 8 valves of French origin in the Largus does not bend the valves;
- but its twin brother with 16 valves actively bends them when the timing belt breaks and mercilessly turns the upper part of the unit.
These are the contradictory and unusual characteristics in modern cars VAZ concern. But don’t forget about another important representative of the company. Lada car 4x4 offers a good 1.7-liter power unit with 8 valves, which has protection against bending of these same valves. The unit may not be very powerful, but it is quite reliable. We offer you a short overview of VAZ engines with recommendations for their operation:
Let's sum it up
VAZ cars can hardly claim to be the optimal and best solutions even in their price range. But today Granta or Kalina often turn out to be the only possible purchase for a Russian family. The sharp increase in prices for other new cars is reflected by the need to buy domestic developments. It should be noted that AvtoVAZ is doing a tremendous amount of work to update its equipment, but even this work has not yet given the desired results.
In modern VAZ lines there is only one own engine that does not bend the valve. This is a 98-horsepower unit on the Priora. However, here everything is arranged in such a way that you may not be lucky, so 16 valves will have to be replaced after a belt break. In other engines, valves and other parts will definitely have to be changed after a belt break. It is much cheaper to monitor the condition of the roller and belts by replacing all these parts in a timely manner.
Job valve mechanism happens as follows: when the piston reaches top dead center, both valves in the combustion chamber close - a certain pressure is created in it. Belt break leads to the fact that valve they do not have time to close in time before the piston arrives. Thus, their meeting occurs - a collision, which directly leads to the fact that the valve bends. Previously, in order to prevent such a problem, special grooves were made for the valves on older engines. On new generation engines there are also similar notches, but they are intended only to avoid valve deformation during engine operation and in the event of a belt break they do not help at all.
From a physical point of view, from the moment the timing belt breaks, the camshafts immediately stop, under the influence return springs, which slow down his fists. At this moment, the crankshaft inertially continues to rotate (regardless of whether the gear was engaged or not, whether the speed was low or high, the flywheel continues to spin it). That is, the pistons continue to work, and as a result, they hit the currently open valves. Quite rarely, but it happens when the valves damage the piston itself.
Causes of timing belt breakage
- wear of the belt itself or its poor quality (shaft gears have sharp edges or oil from the seals).
- crankshaft jams.
- pump jams (the most common phenomenon).
- Several or one camshaft is jammed (for example, due to one of them becoming unusable - however, the consequences here are slightly different).
- the tension roller unscrews or the rollers jam (the belt becomes loose or overtightened).
Modern engines, since they are more powerful compared to their predecessors, have much lower survivability. If we consider the cause based on the valves, this problem arises due to the small distance between them and the piston. That is, if at the moment the piston arrives the valve is slightly open, then it immediately bends. Since for greater compression and contraction in the bottom of the piston there is no groove for the valve of the required depth.
On what engines do valves bend?
On cars with 8 valve engine bends less often, but 16 and 20 cl., be it gasoline or diesel, bending occurs in most cases. True, sometimes it can be one or more valves, and if the engine was idling, then trouble will come. But there are few such cases, mostly the consequences are irreversible. A table with a list of engines on which the valves of all popular cars bend when the timing belt breaks.
| Engine | Oppression | Engine | Doesn't bend | |
| 1C | oppression | Camry V10 2.2GL | doesn't bend | |
| 2C | oppression | 3VZ | doesn't bend | |
| 2E | oppression | 1S | doesn't bend | |
| 3S-GE | oppression | 2S | doesn't bend | |
| 3S-GTE | oppression | 3S-FE | doesn't bend | |
| 3S-FSE | oppression | 4S-FE | doesn't bend | |
| 4A-GE | oppression (does not oppress at idle) | 5S-FE | doesn't bend | |
| 1G-FE VVT-i | oppression | 4A-FHE | doesn't bend | |
| G-FE Beams | oppression | 1G-EU | doesn't bend | |
| 1JZ-FSE | oppression | 3A | doesn't bend | |
| 2JZ-FSE | oppression | 1JZ-GE | doesn't bend | |
| 1MZ-FE VVT-i | oppression | 2JZ-GE | doesn't bend | |
| 2MZ-FE VVT-i | oppression | 5A-FE | doesn't bend | |
| 3MZ-FE VVT-i | oppression | 4A-FE | doesn't bend | |
| 1VZ-FE | oppression | 4A-FE LB | ||
| 2VZ-FE | oppression | 7A-FE | ||
| 3VZ-FE | oppression | 7A-FE LB | does not bend (running on a lean mixture (lean burn)) | |
| 4VZ-FE | oppression | 4E-FE | doesn't bend | |
| 5VZ-FE | oppression | 4E-FTE | doesn't bend | |
| 1SZ-FE | oppression | 5E-FE | doesn't bend | |
| 2SZ-FE | oppression | 5E-FHE | doesn't bend | |
| 1G-FE | doesn't bend | |||
| 1G-GZE | doesn't bend | |||
| 1JZ-GE | ||||
| 1JZ-GTE | doesn't bend | |||
| 2JZ-GE | does not bend (in practice it is possible) | |||
| 2JZ-GTE | doesn't bend | |||
| 1MZ-FE type "95 | doesn't bend | |||
| 3VZ-E | doesn't bend |
| Engine | Oppression | Engine | Doesn't bend | |
| 2111 1.5 16cl. | oppression | 2111 1.5 8kl. | doesn't bend | |
| 2103 | oppression | 21083 1.5 | doesn't bend | |
| 2106 | oppression | 21093, 2111, 1.5 | doesn't bend | |
| 21091 1.1 | oppression | 21124, 1.6 | doesn't bend | |
| 20124 1.5 16v | oppression | 2113, 2005 1.5 engineering, 8 classes | doesn't bend | |
| 2112, 16 valves, 1.5 | bending (with stock pistons) | 11183 1.6 l 8 cl. "Standard" (Lada Granta) | doesn't bend | |
| 21126, 1.6 | oppression | 2114 1.5, 1.6 8 cl. | doesn't bend | |
| 21128, 1.8 | oppression | 21124 1.6 16 cells | doesn't bend | |
| Lada Kalina Sport 1.6 72kW | oppression | |||
| 21116 16 class. “Norma” (Lada Granta) | oppression | |||
| 2114 1.3 8 cells and 1.5 16 cl | oppression | |||
| Lada Largus K7M 710 1.6l. 8kl. and K4M 697 1.6 16 cl. | oppression | |||
| Niva 1.7l. | oppression |
Mitsubishi
VAG (Audi, VW, Skoda)
| Engine | Oppression | Engine | Doesn't bend | |
| ADP 1.6 | oppression | 1.8RP | doesn't bend | |
| Polo 2005 1.4 | oppression | 1.8 AAM | doesn't bend | |
| Conveyor T4 ABL 1.9 l | oppression | 1.8PF | doesn't bend | |
| GOLF 4 1.4/16V AHW | oppression | 1.6 EZ | doesn't bend | |
| PASSAT 1.8 l. 20V | oppression | 2.0 2E | doesn't bend | |
| Passat B6 BVY 2.0FSI | bends + breaks valve guides | 1.8PL | doesn't bend | |
| 1.4 VSA | oppression | 1.8 AGU | doesn't bend | |
| 1.4 BUD | oppression | 1.8 EV | doesn't bend | |
| 2.8 AAA | oppression | 1.8 ABS | doesn't bend | |
| 2.0 9A | oppression | 2.0JS | doesn't bend | |
| 1.9 1Z | oppression | |||
| 1.8 KR | oppression | |||
| 1.4 BBZ | oppression | |||
| 1.4ABD | oppression | |||
| 1.4 VSA | oppression | |||
| 1.3 MN | oppression | |||
| 1.3 HK | oppression | |||
| 1.4 AKQ | oppression | |||
| 1.6 ABU | oppression | |||
| 1.3 NZ | oppression | |||
| 1.6 BFQ | oppression | |||
| 1.6CS | oppression | |||
| 1.6 AEE | oppression | |||
| 1.6 AKL | oppression | |||
| 1.6 AFT | oppression | |||
| 1.8AWT | oppression | |||
| 2.0 BPY | oppression |
| Engine | Oppression | Engine | Doesn't bend | |
| X14NV | oppression | 13S | doesn't bend | |
| X14NZ | oppression | 13N/NB | doesn't bend | |
| C14NZ | oppression | 16SH | doesn't bend | |
| X14XE | oppression | C16NZ | doesn't bend | |
| X14SZ | oppression | 16SV | doesn't bend | |
| C14SE | oppression | X16SZ | doesn't bend | |
| X16NE | oppression | X16SZR | doesn't bend | |
| X16XE | oppression | 18E | doesn't bend | |
| X16XEL | oppression | C18NZ | doesn't bend | |
| C16SE | oppression | 18SEH | doesn't bend | |
| Z16XER | oppression | 20SEH | doesn't bend | |
| C18XE | oppression | C20NE | doesn't bend | |
| C18XEL | oppression | X20SE | doesn't bend | |
| C18XER | oppression | Cadet 1.3 1.6 1.8 2.0 l. 8kl. | doesn't bend | |
| C20XE | oppression | 1.6 if 8th grade. | doesn't bend | |
| C20LET | oppression | |||
| X20XEV | oppression | |||
| Z20LEL | oppression | |||
| Z20LER | oppression | |||
| Z20LEH | oppression | |||
| X22XE | oppression | |||
| C25XE | oppression | |||
| X25X | oppression | |||
| Y26SE | oppression | |||
| X30XE | oppression | |||
| Y32SE | oppression | |||
| Corsa 1.2 8v | oppression | |||
| Cadet 1.4 l | oppression | |||
| all 1.4, 1.6 16V | oppression |
How do you know if a valve is bent?
Checking the engine to see if the valves are at risk of bending after a timing belt break
Neither will help you in this matter visual inspection, nor the numbers given in the “valve bend” tables. Even if you have information from the manufacturer about damage in the event of a broken belt, it is unknown how reliable it is.
If you want to check for the possibility of the valve piston bending when the timing belt breaks, you need to remove the belt, set the first piston at TDC, and rotate the camshaft 720 degrees.
If everything went well and it didn’t get stuck, you can continue checking - move on to the second piston. When everything is fine there, then a possible belt break will not lead to negative consequences for the engine of your car.
To avoid this problem (bending valves when broken), it is necessary to constantly monitor the condition and tension of the timing belt. If the slightest unfamiliar noise appears during operation, you should immediately try to find out the cause of its occurrence and inspect the condition of the rollers and pump.
When purchasing a used car, do it immediately no matter what the salesperson tells you. And then such a pressing question as Do valves bend when broken? It won't bother you.
Bent valve signs
When the belt breaks, simply changing the timing belt, hoping that everything went without consequences and you will start the engine, is not worth it. Especially if the engine is on the list of those on which the valves bend. Yes, there are cases where the bend was not large and several valves no longer fit snugly in the seat, then you can turn it with a starter, but often such actions will further aggravate the situation. Since with minor damage everything will work and spin, but the engine will shake, and the consequences will only get worse.
It is best if you remove the “head” in order to check this visually or fill it with kerosene, however, there are several ways to check whether the valve is bent without disassembling the engine.
Main symptom if the valves are bent - small or completely no compression. Therefore it is necessary in cylinders. But, such actions are relevant if the crankshaft can be turned and nothing rests anywhere. So the first thing you need to do is install a new belt, manually, using the bolt on the CV, turn the entire gas distribution mechanism a few turns (you need to unscrew the spark plugs).
How to check if a valve is bent
To determine whether any valve stem is bent, literally five turns of hand turning the crankshaft bolt with a wrench will be enough. If the rods are intact, the rotation will be free; if the rods are bent, the rotation will be heavy. There should also be clearly perceptible 4 points (with one revolution) of resistance to the movement of the pistons. If such resistance is imperceptible, then screw the spark plugs back in, unscrew them one by one and turn them again crankshaft.
Based on the manual torsion force, with one of the spark plugs missing, it is relatively easy to understand in which specific cylinder the valve(s) were bent. However, this method will not always help to accurately determine whether the valve is bent or not.
If the crankshaft rotates freely, then you can check with a compression gauge. Don't have such a tool? Means do a pneumatic test, and checking the tightness of the cylinders is the most The right way, which will give an answer to how the valve plates fit in the seats, without additional consequences when cranked by the starter and without installing a new belt.
How to check if the valve is bent yourself?
For a pneumatic test, there is no need to take the car to a service station; you can find out for yourself whether the cylinder is sealed or not. The easiest way is:
- select a piece of hose according to the diameter of the spark plug well;
- unscrew the spark plug;
- set the cylinder piston to top dead center (valve closed) one at a time;
- insert the hose tightly into the well;
- Trying with all your might to blow into the combustion chamber (air passes through - it’s bent, doesn’t pass through - “blown away”).
The same test can be done using a compressor (even a car compressor). True, you will have to spend a little more time, as you need to prepare. Drill out the central electrode in the old spark plug, and put a hose on the ceramic tip (fix it well with a clamp). Then pump pressure into the cylinder (provided that the piston in it is at TDC).
The hissing sound and pressure on the pressure gauge will tell you whether the valve caps are seated or not. Moreover, depending on where the air goes, determine the inlet bent or exhaust. With curved graduations, air flows into the exhaust manifold (muffler). If the intake valves are bent, then into the intake tract.
Many owners, before purchasing a car, are not yet aware of such a problem as a broken timing belt, and as a result, on some engines the pistons collide with the valves and bend them. This problem is not only experienced by domestic cars, but also in modern foreign cars, and this threatens quite expensive repairs. Older Lada models had this problem, but now we are interested in modern engines and it is them that we will consider. And the picture on the left shows the consequences of this trouble, so carefully read the information below to avoid such a picture, because, as they say, no one is immune from this.
Bends valves on the following engines
- 16-valve engine, 1.5 liters. Although it is no longer installed on cars, at one time there were quite a lot of them on the tenth family. That's when the owners of these cars felt what it was like. Using the 2112 as a personal example, my valves bent 2 times. And in both cases, not even 10,000 km had passed after replacing the timing belt.
- Model 21126, which is currently installed on both Kalinas and Priors and Grants. As is already known, a collision between valves and pistons is also inevitable when the belt breaks. Moreover, repairs can be very expensive, since in addition to all this, the entire piston system can break, starting from the pistons themselves and ending with scuffs on the cylinders and bent connecting rods.
- Modification 21116, which is now installed on both Grants and Kalinas recently. Although this 8-valve unit has remained virtually unchanged, it will bring a lot of trouble when pistons and valves meet. This happens due to the fact that piston group This engine has a lightweight one, so there is no space left for the recesses in the pistons - accordingly, the valves bend.
- 1.4 16-cl. For the first time the engine was installed on Kalina and it is also unsafe, although quite economical.
- VAZ 21127, which will be installed on the Lada Kalina for the first time. It has a volume of 1.6 liters with a similar design to its predecessor from Priora, but with slightly more power. It also belongs to this list of “dangerous” motors.
The valves do not bend on engines such as:
- 1.5 8-cl. and 1.6 8-cl. Power unit with a smaller volume was installed on earlier versions of cars. And 1.6 for later ones, including Kalina too. Everything is fine here and no timing belt breaks are scary, since the pistons have deep recesses for the valves, which are quite enough to avoid a collision.
- 1.6 16-valve modification 21124. This engine was installed on the VAZ 2112 at one time and was in quite popular demand, as it was both powerful and reliable in this regard.
To at least somehow reduce the likelihood of getting into expensive repairs, be careful when choosing components and spare parts. Change the belt in a timely manner and before purchasing it, carefully inspect it for the presence of a seam, and if there is one, it is better to discard it. And don’t forget about the videos, which should also be of high quality.
