The timing belt is the part that drives the timing belt and crankshaft... The main function of the part is to supply gasoline to the car engine. Without this mechanism the car will not be able to move. The belt not only drives the shafts, but is also involved in the cooling system.
It is a very important part in a car. Its breakdown can stop several running systems at once. Where the belt is located depends on the make of the car. Usually located at the front of the vehicle. On older models, it can be found between the engine cylinder and the radiator. Now car manufacturers are trying to hide this part well. But to get to it, it's enough, unscrew a couple of protective plates and it can already be repaired. The belt itself is made of rubber or rubber. It has a closed-type toothed shape. The teeth are in inside... They serve to grip the rotating gear well. The belt is made for each car model separately.
Causes of a broken timing belt
A broken belt can bring many problems to the car, because with its help the main parts of the engine are involved. When the belt breaks, the shaft stops in one position. While the wheels continue to spin, the stress on the valves is so great that they begin to bend. It's good when it happened with no high speed car. But if somewhere, then on the highway, where the minimum speed is 100 kilometers per hour, the result can be tragic. The repair may not end with the replacement of one part. It turns out to be a very costly breakdown. The complexity of the breakdown directly depends on the complexity of the engine itself. Let's consider the main engines. A simpler 8-valve engine can simply get off with a belt change. The main problems arise with a 16-valve engine, it is necessary to change the main engine parts. Driving this type of car is not only dangerous, but also very expensive. But if, constantly monitor the belt, problems may not arise. Let's designate the main ones.
There are several reasons for a broken belt:
- Not high-quality material from which the belt is made.
- Careless assembly of the engine itself.
- Excessive wear on the part.
- Deterioration of the elasticity of the material, consequent rupture of the belt.
- Poor pump roller tension.
- When the shaft is jammed, the load is distributed to the rest of the parts. The belt breaks down and breaks. This case is very rare, but still it is.
Timing Belt Wear Signs
So, how can you determine if the belt can still be used, or it's time to change it. Let's mark some signs of wear on this part. The main marks will appear on the jagged part. Identify the part that cannot be exploited. So, worn out belt may flake, shag or crack. The working time of the part is usually affected by bad roads, dirt, or the use of a car in constant city traffic jams. It is recommended to change the timing belt every 50 thousand kilometers traveled by the car. Some drivers, in a place with a belt, change the rollers along which it moves. After all, if the rollers jam, the belt will surely break. Problems can arise with the engine itself. Change worn-out parts during the time, because then big problems may arise.
If you're lucky, a torn belt did not bring problems with other parts. Any master in the service station will help you with its replacement. But replacing the belt is a fairly simple repair that almost everyone can handle. To start, rear wheels need to be fixed, we substitute the wheel chocks under the wheels. If you don't have them, then you can get by with simple bricks. The front of the car, jack up. In this case, you need to unscrew the front right wheelso that the shaft is visible. It is necessary to dismantle the pulley, we must remove the belt from the hydraulic booster, behind it we remove the spark plug generator and the air condenser pump. After this dismantling, you need to remove the engine support, which covers the belt we need. Then we remove the belt, unscrew the bolt that fixes the roller. In its place you need to put a new belt. It is very important, when installing, the belt must be tightened well. We return all parts to their original position. The repairs are completed safely!
In this article we will talk a little about the signs of timing belt malfunctions.
The timing belt is critical nodeensuring the correct functioning of the gas distribution system and power unit generally. After all, it provides simultaneous rotation of the crank and camshafts and, therefore, the synchronous operation of the pistons and motor valves.
In addition, if there is a breakage or slipping of the timing belt teeth, in many engines this leads to irreparable consequences when the piston "meets" the valves. As a result, you have to fork out for expensive repairs to the cylinder head, and possibly for replacement piston group.
Signs of a faulty timing belt
As you can imagine, the role of the timing belt is very important. Therefore, its condition must be monitored in the most careful way. Let's consider the main signs of failure or impending breakage of the belt.
There are some signs of a timing belt malfunction:
(typography list_number_bullet_red) 1. Exhaust turned black; || 2. Excessive vibration of the power unit during operation; || 3. Complication of starting the motor; || 4. The appearance of extraneous noise from the engine. (/ Typography)
In any case, if at least one of the described symptoms appears, it is necessary first of all to check the condition of the timing belt. It is better to carry out this procedure at a service station, however, due to its simplicity, experienced motorists may well do this on their own.
In addition to the above-described indirect signs of a timing belt malfunction, there are direct "symptoms" of its failure. In this case, a certain amount of work will be required. However, they do not differ in complexity, therefore they can well be produced independently. Moreover this procedure is the next and mandatory stage of verification in case of revealing indirect signs.
So, you will need to remove the belt guard or part of it. It all depends on specific brand and car model. Next, you need to inspect the entire length of the belt, turning the engine crankshaft. It is important to inspect the condition of the timing belt teeth, as well as pay attention to the presence of cracks and other signs of damage or wear on it. In addition, it is necessary to check the degree of its tension. If this element of the timing system is found to be contaminated with oil or coolant, then it is necessary to eliminate the cause of the leakage of the latter in order to exclude their further getting on the belt. After all, oil and antifreeze can destroy the material for making the belt.
There are also indirect signs of a timing belt malfunction, which can subsequently provoke its breakage or excessive wear and overshoot of the teeth. These include critical wear on the belt tensioner or belt pulleys. In this case, there is no possibility of normal tension of this element. This leads to overshooting of the teeth. high revs... In addition, a loose belt is more prone to breakage. The tensioner on some models may be a pump. Therefore, with its wear or failure, the belt tension is also weakened, which leads to the above-described consequences.
(typography pre_red) SUMMARY ... (/ typography)
It is necessary to know the characteristic signs of a timing belt malfunction - this way you can prevent serious damage to the system. Finally, it is worth noting that each car manufacturer indicates in the owner's manual the timing for replacing the timing belt. It is necessary to strictly adhere to this instruction and replace this unit even a little earlier than the specified mileage.
And when choosing a belt, give preference only to original spare parts from well-known and reputable manufacturers. In this case, the durability of the timing system, and, consequently, the entire power unit will be ensured.
Timing Belt SymptomsThe timing belt is part of the timing mechanism required for the injection of fuel fluid and the exhaust of exhaust gases. Often, car service specialists insist on replacing this part, even if it seems that the car is working properly. To avoid sudden damage, it is worth figuring out how often to change the belt, what are the causes of the breakdown and how to determine the need for replacement.
It is necessary to remember how the engine works in order to understand what the timing belt is for. First, fuel is injected into the cylinder, the inlet valve opens and the piston is lowered. When this valve is lowered, the spark plug sparks and the fuel ignites.
The principle of operation of the timing
Then another valve opens - the outlet, the piston goes up, and the released gas comes out. As a result of the engine operation, the shaft is started and the car moves. It is the timing belt that ensures the synchronous operation of valves and pistons, connects the camshaft to the crankshaft. Thanks to him, they rotate simultaneously, while the first one rotates twice as slow as the second.
The belt also rotates the water pump drive gear. The timing or gas distribution mechanism includes two rollers located under the camshaft pulley. The first one is tension, it is on the left and creates required level belt tension. On the right side there is a support roller.
Timing device
A spare part is made of reinforced rubber with teeth on the inner surface, thanks to which it does not slip during operation. These teeth correspond to the toothed surface of the pulley. crankshaft and timing gears. The belt itself consists of three layers:
- The cord is made of fiberglass threads.
- The next layer is usually nylon.
- The outer rubber jacket protects the inner layers from damage and makes it more elastic.
Timing belt
Now the most common models are made of metallized rubber. But over time, any modification can stretch, crack, break. The wear increases under the influence of external and internal factors.
Timing belt cracks
When the engine is running, the pulleys rub against the belt, so it gradually wears out and becomes unusable. This does not happen if the car uses a chain drive instead of a belt drive. However, the installed chain is corroded and the motor runs noisy with it.
To avoid emergency situations it is advisable to check the condition of the part every month. The resource is reduced when dirt, soot, technical fluids or machine oil. This problem occurs when the protective cover is damaged or engine components are worn out.
Dirt inside the timing
The rollers also affect, if you refuse to replace them in a timely manner, they can damage the gear rubber at any time. The selected manufacturer also affects the service life. Doubtful products at a suspiciously low price can fail at any time.
The product you have purchased may be counterfeit, especially if purchased from a location other than authorized dealer... When overloaded, such a part will fail first. Causes of breakdowns - low quality fake models made of inferior material.
Torn timing belt
Timing belt eight-valve the motor must be changed after every 50,000 km.
Have sixteen-valve engines, this spare part wears out faster and requires replacement after 40,000 kilometers.
Based on the figures indicated, the average replacement period is 50 thousand km.
Experts recommend checking the belt tension at 25 thousand km and, if necessary, tightening it. If soon after replacement it was necessary to change the part again, but the rollers remained, this should be taken into account. Then, from the resource of the new part, you will have to subtract the number of kilometers that the rollers worked before. However, it is recommended to change the rollers together with the belt.
Complete set of a new timing belt
Many manufacturers indicate that when operated in hot climates, the service life is reduced by 25-30%. You should always take into account the make of the car and follow the recommendations of the carmaker. In rare cases, the resource can reach up to 90,000 km.
You can compare the frequency of replacing the timing belt with other parts in the table:
Incorrect installation, such as too much or too little tension, often leads to damage. Weak tension will cause overshoot on the pulleys. If the belt moves even 1 notch, it will cause problems with iCE operation up to complete failure.
In the event that the belt is overtightened, it begins to stretch and eventually breaks off. Then the wear of the timing elements, including rollers and bearings, increases. Also, a common mistake during installation is non-compliance with the alignment of the marks.
Many elements are labeled, including pulleys. They allow you to set the valve timing. Incorrectly aligned marks will at least lead to a decrease in motor power. In an unfavorable combination of circumstances, even with a working belt, the valves may bend.
If the alignment is not observed, the timing belt may slide off the gears
You can determine that the installation was done incorrectly by the sound of the motor. It should work without extraneous noise, for example, if the tension is excessive, the hum of the rollers is heard. To avoid premature wear, loosen the fastener, rotate the roller 15 degrees and fasten.
A common mistake when replacing is a new belt is installed, but the rollers are old. You need to change these elements at the same time, after a certain run. The only exceptions are cases when a recently purchased belt is broken and the rollers are new.
Replacing the timing belt rollers
A worn roller is jammed or slipping. It is capable of damaging the belt at any time, and during diagnostics it can work normally. As a result, the replacement will have to be done again. Malfunctions of other timing units - the crankshaft, camshaft or pumps.
If the engine is running extraneous noise the belt drive area is most likely defective. When loud noise, you should immediately turn off the engine and contact the service center.
Timing inspection in order to identify breakdowns should be carried out every month
During diagnostics, small cracks on the rubber may be found, but this does not mean that you need to buy right away new part... Since the product is reinforced as long as the internal metal part remains intact, no replacement is required. But if the metal part is damaged, the belt is already considered unusable. Extraneous noises appear, it becomes difficult to start the engine.
Another sign of breakage is black exhaust. Strong vibrations are also possible in the area of \u200b\u200bthe engine. Often the engine overheats when traveling. In the above cases, it is better to contact a service station, but if you wish, you can inspect the belt yourself.
For checking, completely remove the protective cover. The scheme of actions depends on the specific make and model of the car. Then the crankshaft is cranked to rotate the belt along its entire length and determine its condition.
Make sure the teeth are not damaged, there are no cracks or breaks on the surface. The degree of tension must be checked. If traces of oil or coolant are found, the cause of the leak must be identified and eliminated.
It is important to check that the belt has not started to delaminate. If it has hardened, then it is also considered to be out of order. To check the rubber, you need to press with the tip of a screwdriver, if there is no dent on the surface, then it has hardened.
The main problems, their symptoms and solutions are shown in the table below:
| External signs | Probable cause | Remedies |
| Tensile tear |
1) Excessive tension. 2) Entry of a foreign body into the drive. 3) The belt is broken due to rough handling. |
1) Correct the tension. 2) Check the integrity of the box and install it correctly. 3) Follow the installation instructions. |
| Cutting a tooth | 1) Misalignment. 2) Weak tension. 3) Jamming of the conducted part. |
1) Correct the alignment. 2) Increase the tension. 3) Eliminate the cause of the jam. |
| Notches on the teeth | 1) Tension too loose. 2) Loss of tension during operation. |
1) Correct the tension. 2) Check the tightener screws are secure. |
| Teeth wear | 1) Worn pulleys. 2) Incorrect tension. |
1) Replace damaged pulleys. 2) Correct the tension. |
| Top edge wear | 1) The tension is too tight. 2) Irregularities in the pulleys. |
1) Install with the correct tension. 2) Replace deformed pulleys. |
| Base cracks | 1) Wear of the reverse damping roller. 2) High temperature. 3) Low temperature. |
1) Replace the roller. 2), 3) - eliminate the cause of the incorrect temperature. |
| Edge wear | 1) Non-parallelism. 2) The flanges are damaged. |
1) Correct the parallelism. 2) Replace damaged flanges. |
| Oil contamination | 1) Oil leak. | 1) Replace broken oil seals. |
| Extraneous noise | 1) The flanges are damaged. 2) Non-parallelism. 3) Strong tension. 4) Insufficient tension. |
1) Replace damaged flanges. 2) Correct the parallelism. 3), 4) - install with the correct tension. |
In the event of wear or damage to the timing belt, the valves will not open and close synchronously. As a result, the engine life will decrease. If it's time to replace the timing belt, then the part has exhausted its resource and can break at any time.
Therefore, with sufficient mileage, the timing belt needs to be changed, even if it seems whole. If you refuse to replace it in a timely manner, engine parts may be damaged. Most often, valves break and tension roller... Generally, the belt and roller have the same service life. Therefore, it is recommended to change them at the same time.
A great danger is the belt jumping off and breaking. Then the gas distribution mechanism stops, and the valves do not have time to close. In a matter of seconds, the pistons still moving by inertia hit the valves and bend them.
Bent valves
The pistons themselves are also damaged. In this situation, you have to pay for overhaul engine. In addition to the belt, the following elements have to be changed:
- valves;
- cylinder block gasket;
- camshaft.
In the worst cases, you will have to completely change the cylinder head
When the belt breaks during a ride, the car can be involved in an accident. Even if an accident does not occur, a tow truck call will be required. In this case, engine overhaul often exceeds the cost of a new engine.
The design of some cars is designed so that when the belt breaks, the valve does not deform. But in most new foreign cars, such protection is not provided. You can find out about the availability of protection by marking the engine.
In official service centers, belts are sold under the brand name of the auto concern that produced the car. In fact, these parts are made to order by other firms. Due to the brand, the cost for the officials is 20-30 percent higher. But the buyer will make the wrong choice, and the installation will be done by specialists.
Verified brands are listed below:
- Contitech are premium products from Germany.
- Bosch is a German manufacturer of quality auto parts.
- Dayco - inexpensive belts from the USA.
- Gates is a reinforced nitrile product that claims to have three times the resources of the competition.
If the car enthusiast knows from which company the carmaker buys spare parts, then he can choose its products. It is convenient to choose an analogue of this company, it will be cheaper, but will not be inferior in quality.
It is important to beware of fakes, if the teeth are crooked, or the inscription is crooked, you should not buy the part
The belt is sold complete with rollers, average cost set for domestic auto - from 1200 to 1500 rubles. Spare parts for foreign cars will cost 2000-3000 rubles. In some cars, you have to change the crankshaft drive gear, prices for which start at 2,000 rubles.
First, unscrew the casing with a wrench.
With a 17 mm head, loosen the generator tension bolt. The generator is squeezed out with a fitting and the old generator belt is removed.
The pulley going to the generator is fixed, a key is inserted into it and rests on the engine block. The wheel under the generator is removed or turned to the side. A head with an extension is put on the pulley bolt and begin to unscrew. When it spins, you can pull off the pulley.
Align the marks on the shafts. The mark should be against the metal strip. Each shaft is rotated with a head and brought to the desired position.
Turning the nut on the tensioner pulley loosen the timing belt until it comes off.
The new timing belt is put on the lower shaft. Then it is threaded through the rollers and the upper shaft.
Check the marks, adjust and tighten the tension roller. The tension should allow the belt to wrap on its straight part, but it should not rotate 180 degrees. Then the pulley is screwed back on, the alternator belt is put on. The generator is wrung out, the generator belt is pulled and tightened. The box cover is screwed on.
You can get acquainted with the installation process in detail by looking video:
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At the heart of any power unit and one of the main components of any internal combustion engine is the gas distribution mechanism. Its main function is to control the intake and exhaust valves. On the intake stroke open intake valves... The fuel mixture is fed into the combustion chambers. On the exhaust stroke, the exhaust valves are opened and exhaust gases are removed from the cylinder. This mechanism is generally quite reliable if you follow the rules for operating the car. But sometimes it also fails. Let's look at the main timing problems, their causes and repair methods.
Timing device
To begin with, let's briefly recall how these mechanisms work. On most engine models it consists of the following assemblies and parts.
So, the valves are controlled by the camshaft. Most often it is made from steel or cast iron. It is installed in the crankcase. This crankcase covers the timing case cover. Also on modern engines the camshaft can be found in the cylinder head. As the shaft rotates, it acts on the cams, which in turn act on their valve.
Also, pushers are provided in the design - they are steel or cast iron. Their function is to transfer force from the camshaft and cams to the valves.
The mechanism has two valves - intake and exhaust. Their task is to serve fuel mixture into the combustion chamber and then removing the exhaust gases. The valve is a flat head stem. The inlet and outlet elements are different from each other. The difference concerns the diameter of the head or plate. These timing elements are made of steel and heat-resistant steel (in the case of exhaust valves). The leg is a grooved rod. It is needed so that the springs are fixed. The valves can only move towards the bushings. To prevent oil from getting into the cylinders, use sealing caps. An outer as well as an inner spring is attached to each of the valves. The rods in the timing device are necessary so that force is transmitted from the pushers to the rocker arm.
Rotates due to the drive. It can be chain or belt. The drive transmits rotation from the crankshaft. The crankcase makes one revolution per two crankshaft revolutions - this is the engine's duty cycle.
Possible malfunctions
Timing faults include incomplete valve closure, excessive clearance between the valve stem and the toe of the rocker arms. Gears, pushers, rods, rocker shafts, bearing bushings and camshaft journals also wear out.
Consider the causes and consequences of some typical breakdowns this mechanism, as well as signs of timing failure.
Reducing compression
One of the symptoms of malfunctions is a decrease in engine compression and popping in exhaust pipe... This occurs after carbon deposits and shells have formed on the valve. Often the element can burn out. The reason for the burnout lies in the loose fit of the intake and exhaust valves to their seats. Other factors also affect the reduction in compression. This is the deformation of broken or worn springs, jamming of the rod in the bushing, lack of a gap between the valve and the rocker arm.
Reduced power
Often, timing malfunctions manifest themselves in the form of a decrease in power, in the form of triplets and metal knocks. These are all signs that the valves are not opening fully. Part of the mixture of fuel and air does not enter the chambers. Subsequently, the thermal gap increases and the hydraulic compensators fail. In fact, this is the reason for the malfunctioning of the mechanism and valves.
Belt or chain worn
This is one of the most basic timing problems, which happens especially often. In this case, the engine can be completely damaged. The drive belt breaks and the pistons hit the valves that have not yet closed, as the camshaft no longer rotates. The reason lies in the wear of the belt or chain.
Timing Belt Troubleshooting and Troubleshooting
Damage to the drive belt is catastrophic and especially frequent breakdown... Let's see the reasons for the timing belt malfunction.
So, most often the element fails due to the rupture of the straight cord. This may be due to the fact that the belt was broken before being installed on the engine. The second reason is the breaking of the twisted cord.
This happens if any foreign body gets between the belt and the camshaft pulley. As a result, it cut deeply into the rubber belt, and tore the cord. It can also happen if the installation is incorrect. It happens that inaccuracy leads to this malfunction - the camshaft pulley could be rotated with a sharp screwdriver.
Shearing teeth
This happens due to a weak belt tension. Such a timing failure does not lead to catastrophic consequences, but engine operation may be disrupted. The car may not start. Camshaft pulley jamming and unbearableness can also be distinguished among the reasons.
Notches on the belt teeth
This is due to excessively low tension. It also occurs due to tension loss during operation.
Back strap cracks
Here, experts identify belt overheating, operation in low temperatures... In addition, a worn guide roller can be the cause.
Belt edge wear
If the belt is visually badly worn from one of the edges, then there may be damage to the flange or obsolescence. In this case, it must be definitely changed.
Chain
For a long time it was believed that the chain is much more reliable than a belt drive. And this is true, but the chain is far from immortal. Malfunctions also happen If the belt breaks, then there is a small but chance to save the motor. In the case of an open circuit, the situation can be much worse. The chain is more massive than the belt, and if it breaks, it literally grinds the engine. Valves and pistons are severely damaged. In general, there is only one circuit fault - it breaks.
Among the reasons are the quality of the oil. The chain resource is 250 thousand kilometers, but they rarely walk that long. Cases are widely known when the chain in the engine broke off at a run of 100, as well as 60 thousand kilometers. But this is more often a factory defect in specific cars. Often, problems are associated not only with the oil, but also with the errors of engineers.
Signs of wear
A worn chain will have several symptoms. To avoid having to overhaul the engine (which is usually very expensive), it is necessary to change the chain as it stretches.
If the engine is idling roughly and unevenly, the chain is already "fit". This work of the motor is due to the fact that the valve timing has changed. If the chain chirps in mode idle move, then this is also one of the signs that irreparable timing malfunctions may soon occur.
If, after removing the cover, you can see that the tensioner has reached its maximum distance, if wear appears on the teeth of the sprockets, then it is best to replace the chain.
Timing repair and maintenance
The main problem with this mechanism is worn journals, cams and increased bearing play. To reduce the gap, it is necessary to grind the camshaft journals. This also deepens the oil feed grooves. The necks are ground to fit the repair size. Further, after repair, check the height of the cams.
There should not be even minimal damage on the supporting parts under the necks. There must be no cracks on the bearing housings. After cleaning and washing the camshaft, be sure to check the gap between the journals and the hole in the cylinder head support.
The chain must not be stretched and have mechanical damage... As long as it is not worn out, it can be adjusted. Unscrew the locking bolt half a turn. Then the crankshaft is turned 2 turns and then the locking bolt is screwed in.
The rest of the troubleshooting of the timing is to replace the worn out elements. It is also necessary to periodically adjust the valves on vehicles that do not have hydraulic lifters.
Conclusion
As you can see, the most popular problems are drive belts and chains. This is what most often specialists have to deal with during repairs. Other breakdowns are less common. But it is worth remembering that it is difficult to independently diagnose this node - often the symptoms can correspond to other breakdowns. It is also worth remembering that most timing problems will lead to disruption of the distribution phases. And then you can start looking for the reasons and ways to troubleshoot the timing. You can independently carry out the adjustment, and it is better to entrust everything else to specialists.
