Often in the conversations of motorists, phrases flashed: “I got to be repaired, the belt broke, the valve was 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.
This interaction is strictly coordinated, otherwise the normal operation of the engine will not be ensured.
The principle of operation of the valve-piston system
Let's take a compression cycle as an example. When the piston, compressing the combustible mixture, approaches the top dead center, it almost comes close to the combustion chamber (on diesel engines - to the surface of the head). If at this moment any of the valves is not closed, then the loss of compression will be the lesser evil. Most likely, the valve, the rod of which is rigidly held by the rocker arm (or the cam of the camshaft) from above, will take the piston strike.
The valve bends in the event of a collision of the valve with the piston
In very rare cases, the piston crown has recesses in the piston crown to avoid collisions. From the above, 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.
The coordination of the timing with the crank mechanism is ensured by the precise installation of gears or sprockets. To do this, alignment marks are made on them and at certain points of the engine.
By the type of torque transmission, the drive of the gas distribution mechanism can be:
- Belt
- Chain
- Gear
Consider their common malfunctions, which can lead to bending of the valves.
Timing drive device
Consequences of a broken timing belt
Some curious motorists are interested in the question: is it possible to bend the valve with a starter? The answer is easy! Just do not set the sprockets or gears "by the marks" - and the key is ready to start! If the engine starts, you will immediately learn to recognize the symptoms of kinked valves. Although, if you do not "miss" much, then everything can be fixed by assembling the timing drive according to the rules.
If only one valve is bent, the engine will run unevenly. Even if it's a V-shaped "six" - hear it.
If, after the restoration of the camshaft drive, the engine runs smoothly and develops the same power, then you are in luck and the manufacturer has prudently supplied pistons with sufficient indentations in the bottoms. But, unfortunately, this is not always possible. First of all, when designing a motor, the designer achieves a combination of many seemingly contradictory qualities of his "brainchild". Let's say such as economy and power. This can to some extent serve as an excuse for the fact that on 16-valve motors, the valve often bends when the timing belt breaks.
Such problems are especially acute for the creators of diesel engines, in which the compression and the necessary swirling of the fuel mixture set the power characteristics. Therefore, the combustion chamber is made in the piston crown and often has a whimsical shape.
On diesel engines, the valve bends more often than on gasoline
However, behind this is the accurate calculation and simulation 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 the most efficient combustion of the fuel mixture. The piston comes very close to the block head. Therefore, it is not yet known for certain whether there are diesel engines that “do not bend the valve”. Although, perhaps, the human genius coped with this disaster.
Repair
Curved auto engine valves
Never try to repair bent valves in any way!
Replacement, and only replacement!
If you straighten the valve "by eye", then you risk making yourself more trouble. The hand-rebuilt valve is unlikely to be aligned with the guide bushing and will press firmly against the seat. And if you want to "slightly" trim the rod, then 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 carefully as possible. After all, a blow can damage the guide bushings, valve seats. There are cases when the connecting rods were bent. Breakage of rocker arms is also not uncommon.
Models of VAZ engines, the valves of which are not “afraid” of breaking the timing belt:
VAZ 2111 1.5l; VAZ 21083 1.5L; VAZ 11183 1.6l (8 valve); VAZ 2114 1.5l and 1.6l (both 8 valves)
It is known that the 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 in his favorite car bent at least one valve, even once, such a person already begins to understand that even “glands” do not have iron patience and will try to become a good master of their “horse”.
In conclusion, it is not superfluous to add - watch your car, do not hesitate if there is a reason to “look under the hood”.
The gas distribution mechanism (GRM) is one of the most important elements in the design of diesel, gas and gasoline engines. There are not so many possible breakdowns for this node, but if they happen, then you should tune in to the most serious consequences. Most often, the timing belt breaks, which on most modern cars is made of high quality rubber. The danger of this malfunction is very high, because an interrupted drive often bends the valve. For more information about the essence of belt breakage, methods of eliminating its consequences and preventing breakage, read below.
Risk of malfunction
For more or less experienced motorists, it has long been no secret that monitoring the health of some units significantly extends the service life of others. This rule is more than ever applicable to the timing belt under consideration today. In many ways, this state of affairs is due to the fact that the drive of the gas distribution mechanism performs the most important function, connecting its elements into a perfectly working system. The latter, by the way, ensures the synchronous operation of the valves and pistons of the motor, and in such a way that they do not interact with each other at all and serve their full operational life.
Timing operation is truly debugged, however, a failure can occur in such a device. The most dangerous of these, primarily for the condition of the engine, is a belt break. This malfunction provokes the asynchronous operation of the valves and pistons of the motor, which results in the following sequence of phenomena:
- First, the valves get stuck in the open position;
- Then the pistons start hitting them. The blows continue until the motor that has lost its compression stalls;
- As a result, either the valves, or the pistons, or other elements of the engine (cylinder head, valve tracks, timing) fail and require expensive repairs.
In rare cases, of course, it is possible to "get off with a little blood", that is - exclusively by breaking the timing belt, but this happens infrequently, so it is worth preparing for the most serious consequences.
Belt break diagnostics
Many inexperienced motorists often ask themselves the question - "How to diagnose a broken timing belt?" In fact, it is very simple. The specificity of this breakdown is such that if it is present, the motor will simply refuse to work. Immediately at the moment the belt breaks, a short but loud bang occurs in the area of the engine compartment, after which the engine stalls. At the moments following the break of the belt, starting the engine becomes impossible, and the starter turns quite easily and with a characteristic metallic knock (the piston hits the valves). Naturally, all this is accompanied by the loss of compression engine.
For a better and more correct diagnosis of a timing failure, an analysis of what happened is not enough. At a minimum, you need to "get" under the hood and check the condition:
- valves (up to a third of all available can be affected);
- parts of the pistons visible through the cylinder head;
- the belt itself.
On most modern cars, the procedure for such a check looks like this:
- The timing is located (it is either in the public domain or under the protection of the motor);
- An assessment of his condition is carried out;
- The cylinder head or its protection is removed and the condition of the internal elements of the motor is assessed.
Due to the fact that the process of replacing the timing belt is very simple, it is quite possible to carry out such repairs in the place where the breakdown occurred, therefore, as an ambulance, it is better to have a spare drive with you specifically for the operating model of the motor.
Reasons for the break
Most often, the valve is oppressed due to a broken timing belt, but few know why it breaks. Naturally, operational wear is at the top of the causes of this malfunction. It is important to understand that a rubber belt, even of high-quality production, is not capable of driving more than 70,000 kilometers, so it needs to be changed every 60-65,000. You can determine if a drive should be replaced ahead of schedule by examining it in detail. The surface of the belt, at a minimum, should not contain any cracks, torn teeth or oil stains, and in the best case, no wear and tear.
In addition to wear and tear, the timing belt can break for the following reasons:
- the wedge of the gas distribution mechanism due to its internal breakdowns (rollers and tensioner often suffer);
- installation of the drive with a weak or excessively strong tension;
- frequent use of the machine under heavy load conditions;
- violation of the tightness of the engine protection;
- oil on the belt due to leakage of gaskets or wear of oil seals.
The complete elimination of the factors noted above, the timely replacement of the belt and the use of only high-quality parts are exactly what will help to reduce the risks of its breakage to a minimum. Otherwise, it is worth preparing for the consequences that take place when the timing belt breaks.
Replacement procedure
The process of replacing a broken belt is conventionally divided into the organization of three main activities:
- Purchase of necessary spare parts;
- Tool preparation;
- Directly repair.
For a better understanding of the entire procedure, it will not be superfluous to consider each stage separately. Let's start, of course, with the purchase of the necessary spare parts. In addition to the belt itself, it is also required to purchase bypass rollers and tensioners. All auto experts agree that they need to be changed together with the timing belt and not save on this. When purchasing certain spare parts, it is important to make sure that they are identical to the parts installed earlier. Achieving the goal is not so difficult if you turn to the technical documentation of the engine being repaired or remove the old timing elements and use them as an example.
As for the toolkit, its minimum list includes:
- Screwdriver Set;
- mount;
- jack;
- wrenches and heads;
- pliers.
Having prepared and purchased the necessary parts, you can begin repair work. The replacement process itself looks like this:
- Disconnect the battery (just disconnect the negative terminal);
- We get access to the belt;
- We combine the timing marks;
- We dismantle the replaceable rollers and tensioner;
- We unscrew the faulty drive;
- We clean the seats;
- Installing new elements;
- We are replacing other consumables of the removed motor units (gaskets, for example);
- We assemble the car in the reverse order;
- We use the machine, henceforth not forgetting to monitor the condition of the entire timing belt and the belt in particular.
Note! If, in addition to the torn belt, any other breakdowns were identified, be sure to eliminate them as well. Otherwise, the repair will have a short-term effect and, in fact, become useless.
If you have any questions - leave them in the comments below the article. We or our visitors will be happy to answer them.
VAZ cars of the 2112 family were produced with one of four engines. Two of them are 8-valve, two more are 16-valve. The 8-valve motors have grooved pistons so the valves cannot bend. But this property does not apply to any Lada cars: almost all 8-valve valves during the transition. It is known on which of the engines VAZ-2112 never bends the valve - it remains the motor 21124 (1.6 16v).
See how difficult it is to change valves on a Ten. All steps in one video
We are talking about 2111 and 21114 engines. They are injection engines, and the shape of the pistons was inherited by them from the 2110 carburetor engine.
ShPG elements (pistons) 2110-1004015
Actually, the same pistons were installed on three different 8-valve valves: 2110, 2111 (1.5 8v), 21114 (1.6 8v). The piston article number is 2110-1004015.
Two deep grooves ensure that any of the valves, intake or exhaust, can not "meet" the surface of the piston, even if the timing belt breaks.
The standard 8-valve valves on the VAZ-2112 do not bend the valve, no matter what some owners say. Sometimes, and if the valves fly out more than provided by the VAZ, then there will be no guarantee against bending. Therefore, follow the regulations.
And the following is provided:
- Intake valve lift - 9.4 mm;
- The lift of the exhaust valve is 8.95 mm.
We quote the values taking into account the thermal gap. Whoever exceeds them will get the result.
Are 16-valve engines bent?
ShPG elements (pistons) 2112-1004015 and 21124-100401504
In pistons 2112-1004015, the grooves are indeed made. The probability of kinking is reduced, but it is not reduced to zero. Therefore, always pay attention to the rollers and rollers on a 16-valve engine.
The VAZ-21124 engine is one of those 16-valve engines that do not bend their valves. The grooves are made so that no valve meets the piston.
Items:
- 2112-1004015 - the piston of the VAZ-21120 engine (1.5 16v);
- 21124-100401504 - the piston of the internal combustion engine VAZ-21124 (1.6 16v).
Make no mistake when choosing.
Motors 21124 are in short supply!
One of the most beloved engines on a 12-ke is 124. It does not bend the valve, it rides well, but what else is needed?
The number of VAZ-21124 engines produced for the entire time is difficult to calculate. Maybe it even exceeds the number of 20 motors. The 21124 engine had a Euro-4 version, and this engine, regardless of the version, is in short supply. Prices also remain high. Well, a less voluminous 16-valve valve is rated lower, despite the fact that it is more powerful!
Used motors that bend their valves are no longer needed by anyone. It cannot jam, the belt will break and the owner "got" on the capital. Draw conclusions.
Tuning example video: increasing the volume from 1.5 to 1.6
Greetings to you friends on the do-it-yourself auto repair site. Experienced motorists know that a broken timing belt can lead to dire consequences. In particular, there is a great risk of "meeting" the valves that have already come out of the seats and the pistons rising by inertia.
The result is the deformation of the vital elements of the motor, as well as an urgent need to visit the service station and carry out major repairs. But does the valve always bend when the timing belt breaks? Should I be afraid of this?
A bit of history
On the new "tens" 8-valve engines with volumes of 1.5 and 1.6 liters were immediately installed. The first power units (from the point of view of the problem we are describing) were ideal, and the valves did not bend. Although on earlier models of the type eight, nines with a volume of 1.3 this problem was. The reason was that the piston constructively could not "meet" the valves.
Over time, a more modern model VAZ 2112, equipped with a one and a half liter engine, with a 16-valve engine, appeared in the “dozen” family. It was from this moment that the problems began. Many motorists and specialists could not understand why the valve was bending.
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 power of the car to 92 "horses", and on the other - broken timing belt invariably led to collision of pistons and valves, as well as deformation of the latter.
After that, I had to go to the service station and hand over the car for expensive repairs. The constructive fault lay with the pistons themselves, which lacked the necessary recess. As a result, a timing belt break always ended in the same way.
Updated car engine
A similar oversight was adopted and more advanced 1.6-liter 16-valve engines were installed on the new VAZ 2112 cars. Structurally, the power units did not differ much, but one feature was still present. In the new engine, the pistons had certain notches, so the problem described above was eliminated.
Over the next few years, motorists began to forget about bent valves and got used to the reliability of the new 16-valve motors. But the updated Priora model with a 1.6-liter power unit was unpleasantly surprised - the valves also bent when the timing was broken.
At the same time, the final repair was much more expensive. On the other hand, the developers made the belt as wide as possible to minimize the chance of belt breakage. Only those motorists who got a defective belt or those who did not watch their "iron horse" were unlucky.
Unfortunately, even on the new 1.4-liter Kalina engines with 16 valves, repairs cannot be avoided if the belt breaks in motion. So monitoring the status of this node is mandatory.
On which VAZ engines the valve bends, and on which not
Let's draw intermediate conclusions, as well as highlight the most "dangerous" and "safe" models from the standpoint of the likely deformation of the valves in case of belt damage:
1. What kind of engine valve bend? This category includes motors of cars of the following model range - 21127, 21116, 2112, 1194.
2. What kind of VAZ engine does not bend the valve? Motors of such VAZ models as 1183, 21114, 21083, 21124, 21126 (bent until 2013, and now not), 21128 are more reliable.
The current problem has caused a lot of controversy among motorists. Many owners of "problem" VAZs are interested in what to do so that the valve does not bend. 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. The appearance of cracks, contact with the surface of engine oil, excessive stretching, peeling of the edges - all this is a reason to install a new timing belt and not wait for a rupture.
2. Secondly, if the engine is expected to be repaired, you can change the pistons, and in some cases the crankshaft. In addition, some experts recommend (as a way out) the installation of a new camshaft.
But here, of course, one cannot do without consulting specialists. After that, you may need to flash and remove the catalyst.
If you got a car where the valve bends, then do not despair ahead of time. The ideal solution would be maximum attention to the engine and more frequent timing belt replacement... Even that will be enough to keep the risks to a minimum.
As for the replacement of units and expensive repairs, these costs, as a rule, do not justify themselves. Good luck on the road and, of course, no breakdowns.
Sometimes cars give their owners a lot of problems. One of the worst breakdowns is bent valves. This happens when the timing belt breaks. After a break, the valves completely fail. Let's look at the reasons, as well as find out how to prevent and repair.
Why are valves in an engine?
First you need to learn the theory. Probably, every car enthusiast knows the number of cylinders in the engine of his car, but not everyone can answer the question about the number of valves. Most modern internal combustion engines can have 8 to 16 valves. There are such power units, where there can be 24 or more. The valve is an important part of the engine. It is responsible for supplying the fuel mixture to the combustion chamber and for the exit of exhaust gases to the exhaust system. For each cylinder there are two valves: one inlet, the second - outlet. In 16-valve engines, there are four valves for each cylinder, if the engine is four-cylinder. There are also engines where there are more intake elements than exhaust ones. These are three- and five-cylinder engines.
The valve consists of two parts - a poppet and a stem. It is the rod that gets hit when the timing belt breaks. The valves are driven by the action of the camshaft. It, rotating around its axis in the cylinder head, can raise and lower the valves.
It is driven from the crankshaft - these two elements in any internal combustion engine are interconnected by a belt, gear or chain drive. By means of a gear train, the camshaft rotates inside the cylinder block. This gear drives the camshaft in the cylinder head. Today, ICEs are more common, where belts are used.
The latter have a simple design, such a mechanism is cheaper to manufacture. However, their reliability is much lower than in the case of a chain drive. The latter is more complicated - there are also additional elements. These are chain guides and idler rollers.
Why bend?
The situation when the valves are bent can happen in any engine of any design. It does not matter how many cylinders are in the engine and how many valves there are. The reason for the breakdown is simple, and it is one. This is a broken belt in the drive or chain. The latter are torn much less frequently compared to belts. In the case of the chain, it stretches, and the stars jump.
The camshaft stops abruptly after the timing belt breaks. At the same time, the crank will continue to move. For example, valves that are recessed in the cylinders will collide with the pistons when they reach top dead center. And since pistons have a lot of impact energy, they can easily bend or break open valves.
Elimination of the consequences of this breakdown is very expensive. It is necessary to pull out all the damaged valves from the engine. Also, the entire cylinder head and the cylinder head are necessarily affected. It is far from always possible to restore the cylinder head, and then only replacement with a new or contractual one will help.
Causes of a broken timing belt
The most common reasons that lead to breakage of a drive belt is the owners' failure to follow the manufacturer's instructions for replacement. When the car is new and is under warranty, the owners very rarely look under the hood - all the maintenance work will be done by an authorized dealer. When the warranty ends, many try to save money on belt replacement.
Often the pump may fail. In many car models, it is driven by the timing belt. If the pump fails, the system will jam, and the belt will wear out in a few hours. Also one of the most popular reasons is poor quality belts. Therefore, it is better to purchase high-quality and original consumables.
Camshafts can also fail, as well as the latter fall off or can jam - the belt either flies off the gears or breaks. That's why the valves on the VAZ bent.
It is not only a breakage that can occur with a belt. Teeth are often sheared and not easy to find. Teeth can slip if the tension roller spring breaks. On some engines, the camshaft gear has a special.Only a tightened bolt serves as an insurance against turning the gear. If you do not reach it, then there is a risk that the gear will turn, and as a result, the valves will bend. Replacement is the only way out of the situation.
How to avoid trouble?
There is only one way. It is necessary to strictly follow the manufacturer's instructions for replacing consumables. Not only the timing belt is subject to replacement, but also the tension rollers, as well as other elements that mesh with the belt and are indicated by the manufacturer in the regulations.
All components should be purchased only from trusted automotive stores.
Can I bend with a starter?
The starter bends the valves, and easily. This happens if the stars or gears of the timing mechanism are incorrectly installed according to the corresponding marks. Then just turn the starter. If the engine starts, the driver will immediately learn how to recognize when the valves are bent. But if you miss a little in the marks, then breakage can be avoided. In order to solve the problem completely, it remains to assemble the drive according to the rules.
How to identify bent valves?
It is impossible to determine by eye what the valves are bent. This will require simple, simple actions. First, you need to install the timing belt according to the marks, and then turn the crankshaft by hand. It usually takes two to five turns to find out that the valves are indeed bent. If the crankshaft rotates easily and calmly, then the timing elements are intact. When rotation is difficult, the valves are damaged.
It also happens that with free and light rotation of the crankshaft, the valves are still bent. In this case, the problem can be identified by measuring the compression. If the compression is at zero, then the timing elements are damaged. Many do not know how to check if the valves are bent. It will be heard. The engine will run unevenly. This is felt well even on large engines with six or more cylinders.
On which engines the valves will not bend?
Such motors exist. Some engines were even produced by AvtoVAZ. The whole secret lies in the pistons with special grooves on the working part of the piston. These recesses are specially made for the valve. If the timing belt breaks, the element will simply go into these pits, and the structure will remain intact. It will only be necessary to set the gears according to the marks and install a new belt.
How do you know if the engine is bending the valves?
But this will not work. There are no tricks or signs here. It will not work to visually identify whether the motor is safe.
Also, there are no inscriptions or any mentions. Information can be obtained from the instruction manual or from an authorized dealer.
Conclusion
In order not to engage in valve replacement, it is recommended to change the timing belt on time. If this is an AvtoVAZ car, then you can install special protected pistons. But they eat up some of the power and increase fuel consumption. It must be remembered that if the timing belt breaks, not only the valves fail - the entire head can also break. This makes repairs even more expensive. It is not worth saving on the timing belt.
