What 16 valve engine does not bend the valves. Why does the valve bend? How to check if the valve is bent yourself

Many car owners have heard about such engine malfunction as a broken timing belt. This topic is a kind of horror story for novice car owners, and gives rise to many rumors, sometimes not correlated with reality.

The engine gas distribution mechanism is driven by the crankshaft gear. Initially, chains were used for this purpose, and timing belts, which began to be widely used about twenty years ago, aroused mistrust among car owners.

The undoubted advantages of a belt drive over a chain drive are its simple design, low weight and low noise. However, it is not without its drawbacks, the main one of which is the relatively short resource of the timing belt.

The chain drive has a very long service life. If the motor is not abused, the chain may well last more than 200 thousand kilometers. As it wears out, it stretches out and begins to rattle, thus signaling the need for replacement. A high-quality belt, meanwhile, lasts an average of 60 thousand kilometers, after which it needs to be replaced, even if it looks intact. If this is not done in a timely manner, the belt may break.

What happens when there is a break?

The consequences of a broken timing belt depend entirely on the design of the power unit. To imagine what will happen at this moment, you need to turn to the mechanics of the internal combustion engine.

In a running engine, the pistons continuously move from one dead center to another. During the intake stroke, the piston moves down and the intake valve opens; during the exhaust stroke, the exhaust valve opens and the piston moves up. At the moment when the piston is at top dead center, all valves must be closed.

If the timing belt breaks, the camshaft stops rotating and the valves stop in one position. At the same time, the crankshaft continues to rotate by inertia, and the pistons rush towards the open valves.

In some engines, for example, the 8-valve VAZ-2111, the pistons have special recesses to avoid contact with the valves in the event of a break. In this case, there will be no consequences, except that the car will not be able to get to the garage or workshop under its own power.

Modern multi-valve engines are designed to get maximum power from a small volume, so the pistons do not have such recesses, or they are not deep enough. For such engines, a broken timing belt means an inevitable meeting of the pistons and valves, causing the latter to bend.

If the belt breaks at idle speed, as a rule, only a few valves are bent; if the car was moving in gear and the speed was high, most likely the entire set will be replaced.

Car service technicians, as a rule, rightly advise changing the entire set of valves in any case.

The higher the crankshaft speed at the moment of the break, the more severe the consequences. In addition to bent valves, their guide bushings may burst, which in turn threatens the repair or replacement of the cylinder head or the block itself. In addition, the impact may destroy the pistons.

There are even cases where a break occurred on high speed, and all the valves were bent from the impact, the cylinder head received damage “incompatible with life”, the guide bushings burst, and their fragments pierced the pistons through and through. Repairing such motors is extremely expensive. According to statistics, double-shaft (DOHC) engines of Japanese manufacturers more often suffer such damage.

However, in comparison with diesel engines, the consequences of a broken timing belt for gasoline engines, quite light. Due to the specific design, the valves have almost no free play when the piston is at TDC. As a result of the break, the destruction takes on the character of a domino:

• valves bend;
• the camshaft and its bearings are destroyed;
• block head;
• connecting rods and pushers bend.

If a break occurs at high speeds, the pistons can also be destroyed and the cylinder block damaged.

Causes of timing belt breakage

The most common causes of a break are related to the carelessness of the car owner. Chief among them is untimely replacement worn belt. As a rule, automakers set intervals between replacements at 60 thousand kilometers ( real resource a high-quality belt exceeds the replacement interval by 5-10 thousand km). If it is changed for the first time during scheduled maintenance, then in the future car owners often forget about it.

Installing instead original spare parts an inexpensive analogue made in China, you should be prepared for the fact that it will break long before its 60 thousand “go away”. Such savings threaten to be much more expensive, so it is advisable to purchase either standard spare parts or high-quality analogues, which are sometimes more expensive.

In addition, the belt becomes unusable due to the systematic entry of dirt and oil, so you should monitor the condition of the protective casing and pay attention to the appearance of oil leaks from the engine. A foreign object caught between the belt and gear can also lead to either breakage or cutting of its teeth.

In addition to these, the most common ones, there may be other reasons for the timing belt to break, such as jamming or spontaneous release of the tension roller, pump wedge, as well as jamming of the camshaft or crankshaft. Sudden loads on the belt can lead to a break, for example, if the car is often started “with a pusher”.

Signs of a broken timing belt

The main signs of a broken timing belt are as follows:

1. the engine suddenly stopped;
2. it is not possible to start it again;
3. When the starter is running, a metallic knock is possible at the top of the engine (pistons hitting the valves).

You can determine for sure whether the belt is really broken only by looking under the hood. Most likely, there will be a torn belt itself and its damaged casing.

Valves are one of the important parts of the gas distribution mechanism and when the timing belt breaks, they are most often subject to significant deformation. And as a result, it provides expensive repairs to the car owner.

This article describes the principles of operation of the gas distribution system, the reasons why the valve bends, the consequences of a broken timing belt for the engine, and also describes on which engines the valve bends or does not bend when the belt breaks.

The following main reasons can be identified:

• Condition of the timing belt (cracks, worn teeth, the belt is overtightened or loose)
• Failure to comply with the timing of belt replacement (high mileage of the vehicle).
• Entry of a foreign body (check that the protective cover is installed correctly)

What happens in the engine when the belt breaks?

Today, engines with 8 and 16 cl are most often used. They are responsible for compression of the cylinders and for the release of exhaust gases. They move because of the camshaft, which unwinds and presses on the valve.
The engine operating cycle is a periodically repeating series of sequential processes occurring in each engine cylinder.
The engine operating cycle occurs in 4 strokes or 2 revolutions of the engine crankshaft. (such engines are called 4-stroke; there are also 2-stroke engines, but they are not used in cars now).
So you:

• Inlet
• Compression
• Extension
• Release

The valves open and close at the right time. The drive is carried out by cams located on the camshaft. When the cam rotates, its protruding part presses on the valve, causing it to open. Cl. the spring closes it.

Fist- component camshaft (drivers call it a camshaft). The camshaft has bearing journals and cams. Torque from the crankshaft to the camshaft is transmitted by a chain or timing belt.

If with the engine running drive belt breaks b, then the camshaft ceases to be connected to the crankshaft. And it can stop arbitrarily in a position in which one of the valves is completely open. In this case, when moving upward, the piston may collide with the valve, which in this case bends. And as a result, the engine faces serious repairs. The engine will need to be disassembled, the valves need to be replaced, and in some cases the “Head” of the block may also be damaged, so much so that it will need to be completely replaced.

On what cars do valves bend?

On most cars, when the timing belt breaks, the problem of valve bending occurs. It doesn’t even matter whether the engine is idling or driving along the highway. They can still bend. It is important exactly how much the gear is turned when the belt breaks. The bend can occur at 8, 16 and 20 cells. engines, on diesel and gasoline engines, small cars and cars with large displacement. That's why It is very important to promptly replace the timing belt. But a timing belt break does not always lead to bending.

On what cars does the valve not bend?

Some engines have small protection - grooves, which are small notches. These grooves are installed so that at high speeds the piston does not catch up with the closing valve. But when the timing belt breaks, they also help reduce the negative consequences, and in some cases they do not bend the valve at all.

Sometimes car owners grind them themselves, but this is not always correct. Because the presence of these recesses leads to a decrease in the engine, an increase in fuel consumption, and the content of nitrogen oxides in the exhaust gases. Many auto companies have now abandoned such protection.

The most reliable method of combating valve bending is timely replacement of the belt.

What to do to prevent the valve from bending if the timing belt breaks

To prevent the valve from bending, it is necessary monitor the condition timing belt. It is necessary to change it according to the dates specified in the service book (approximately 60–70 thousand km). But it is also necessary to periodically visual inspection belt, even if the replacement date has not arrived. Quite often, the belt breaks immediately after its installation after 1000–2000 km. This happens if the work to replace it is done poorly.

Periodically remove the cover and check the belt. Inspect it from the outside, check the belt ribs and the presence of microcracks. And also it should not be too tight. Carry out such inspections from time to time. As soon as you see signs of wear on the belt, it's time to replace it.

How to understand that the valve is bent

If the belt breaks, there is a small chance of no damage to the engine. Before removing the cylinder head, it is necessary to measure the compression in the cylinders if the crankshaft can be turned. If the valves are damaged, there will be a lack of compression. It is always necessary to disconnect the battery when carrying out repair work on the engine. To facilitate rotation of the crankshaft, it is necessary to remove the spark plugs to gasoline engine or glow plug for a diesel engine.

The crankshaft can only be rotated in its normal position (usually clockwise).

Cost to repair bent valves

Repairs of this type usually cost the car owner quite a lot, at least 15 thousand rubles, and in the event of a head injury, the amount can increase significantly. In case of severe damage, even a new head may be required, and rebuilding does not make sense.

Bent valves must not be bent back! Some unscrupulous car services say that they have spare parts for your car in stock, but in fact they bend them back, which is unacceptable. Be sure to ask to show the deformed parts after the repair.

In order to avoid bending the valves on a car, it is necessary to promptly replace the timing belt on cars, and also remember that the cost of replacing a timing belt is 10% of the cost of repair work if it breaks.

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?

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.

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 hand, broken timing belt invariably led to a collision of pistons and valves, as well as deformation of the latter.

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.

Over the next few years, car enthusiasts began to forget about bent valves and became accustomed to the reliability of the new 16 valve motors. 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.

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:

1. Which VAZ engines bend valves? This category includes the engines of the following cars: 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 not now), 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.

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. Appearance of cracks, contact with the surface motor oil, 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 the engine is expected to be repaired, then you can change the pistons, and in some cases, the crankshaft. In addition, some experts recommend (as a solution) installing a new camshaft.

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.

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.

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 still 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

1. 16-valve engine, volume 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.
2. 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.
3. 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 is due to the fact that the piston group in this engine is lightweight, so there is no space left for the recesses in the pistons - accordingly, the valves bend.
4. 1.4 16-cl. For the first time the engine was installed on Kalina and it is also unsafe, although quite economical.
5. 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.

Once I wrote about the PRIOR engines, they asked me - “”, read it very informatively. In this article, I promised to talk about the very principle of why this happens on some engines and not on others. In general, about the breakdown process itself, today I will try to sort everything out, especially for you “newbies”. I won’t delay, let’s go...

So valves are part G azorasp R dividing m car mechanism (timing mechanism). It should be noted that this part is quite important, without them there would be no exhaust gases released, and compression would not be created in the cylinders during fuel injection and ignition. Modern engines have different numbers from 8 to 32. But most use options with, they are the most common of all.

Principle of operation

“Makes” them work to open and close camshaft, which is located on top, in the block head.

It unwinds and, thanks to special ovals, presses on the valve - it opens, or releases it - it closes. In turn, the camshaft operates on a belt or chain drive from the crankshaft.

The camshaft and crankshaft are necessarily synchronized so that the opening of the valves and the movement of the piston coincide in a certain sequence - when the piston goes down, the valves open (“sink” into the chamber), when the piston rises up, they close (go up), thus creating pressure in combustion chamber, then the spark plugs ignite the mixture and the piston goes down under pressure. This cycle is repeated many times. Here is a short video clip of the work for understanding.

This is a perfectly working scheme, with proper maintenance(timely replacement) everything will run for many thousands of kilometers.

The reason why the valve bends

I would like to note that this can be on either an 8 or 16 valve engine. The reason is simple - it is a broken timing belt or chain. In fairness, it is worth noting that the “chain” very rarely breaks, mostly it stretches and the “hook” sprockets begin to jump, which may also be the reason.

When a break occurs, the camshaft stops abruptly, but the crankshaft continues to push the pistons. Thus, the valves go down and “sink” into the combustion chamber, the piston also goes up - which should not happen during normal operation. They meet at the “top point” and the piston, having high energy, simply bends or breaks the valve. As you can see, everything is quite banal.

Such a breakdown is very expensive - you need to “half” the motor and pull out the bent elements, sometimes even the block head itself suffers (but rarely), so it will also need to be replaced. You can also encounter damage to the pistons (the valve pierces it), but here everything is even more serious, you will need to remove the camshaft and pistons with “connecting rods”.

Why does a belt break and how to protect yourself from it?

1) The most common reason is a simple failure to comply with the instructions for replacing the belt from the manufacturer. As a rule, if your car is under warranty, then the replacement will be under warranty, but if you service it yourself, then many people forget or save on replacement. It “comes out” sideways.

2) Poor quality belt, now there are just a lot of fakes, especially for our VAZs. In reality, they don’t go even 5,000 kilometers (it happened several times in a company car), so it’s better to take proven options. Or exchange it at a service station with a guarantee.

3) The pump fails. In some car models, it is also engaged in the belt and if it fails, it simply jams and will wear out the belt in a matter of hours.

4) The camshaft itself wears out. It is made of metal and it is clear that after some time it will wear out (it may jam), although a lot of time should pass (high mileage).

5) The tension rollers of the timing system fail. They can fall off, they can jam - in any case, the belt will either break, or it will fly off - one end will bend the valves.

There is only one defense here guys. Change the belt on time, as well as the tension rollers and other elements of this system that are assigned to you according to the regulations. Buy “consumables” from official or trusted stores, because fakes sell much less than originals, here you risk every thousand kilometers, in general, a belt is not a spare part that is worth saving on.

Are there options that don't bend?

Of course there are, but now they are very rare. Once again I advise you - there are models of engines that were not bent before. However, unfortunately, there are practically no such people now. That’s why many people carry out such tuning of power units.

The point here is also banal, simple - instead of ordinary pistons they install . Then, even if a break occurs, the valves will simply fall into these holes and nothing bad will happen. It will be necessary to install a new belt and synchronize the camshaft and crankshaft.

“Great,” you say. BUT why then aren’t such pistons installed on all models? After all, this is 100% protection.

Again, everything is simple - such pistons eat up part of the engine’s power, and quite a lot. There is still debate about “how much”. Some say about 5 - 7%, but excuse me, this is DEcent! The thing is that such a piston is heavier, and the compression is not as effective. That is why many abandoned this decision. Many - but not all!