The gas distribution mechanism of the engine is designed for the timely supply of fuel mixture to the engine cylinders and the removal of exhaust gases. The valve mechanism is driven by the rotation of the crankshaft. In this case, the torque from the crankshaft is transmitted to the distribution using a belt or chain. It depends on the car model. But, as a rule, a toothed belt is installed on most modern cars. The timing chain is installed on earlier models, such as the VAZ-2101-07. Unlike a belt drive, a chain drive is more reliable, but it has its drawbacks, one of which is the high noise of the distribution mechanism when the drive is loose.
Appointment of the timing tensioner
To ensure the normal operation of such a drive element as a chain, chain tensioners are installed in the engine design. During the operation of the car, the camshaft drive chain and its tensioner fail quiterare, but it does happen.
Often the chain simply stretches, at this moment noise appears in the motor in the tenacious area. If the chain drive breaks or jumps off, more serious engine damage can occur, which will entail costly repairs. To prevent this, it is important to monitor the condition of the drive and service the timing chain tensioner in a timely manner.
Features of the device of the tension mechanism
Let's consider the design on the example of a VAZ car of the seventh model. The machine is equipped with a plunger-type tensioner. The required degree of tension occurs due to the plunger with a spring.
The operation of this device is as follows - under the influence of spring pressure, it leaves its seat and rests against the shoe of the chain tensioner. Thus, the part pushes the shoe until it meets the resistance of the grip. Due to the action of a powerful spring, the sagging of the drive disappears and tension occurs. In this case, after adjusting the tension, the plunger of the mechanism is locked with a cracker. During long-term operation, the auto chain gradually stretches, and it needs to be re-tensioned. To do this, unscrew the locknut of the plunger lock, after which the spring will again sample the sag.
This type of chain tensioner has one major drawback.
Namely, the possibility of small particles of litter getting into the seat of the plunger, while increasing the likelihood that it will jam incase. You can fix such a malfunction by tapping on the body of the mechanism with a wrench, sometimes this repair method helps. If the tensioner housing is damaged, it must be replaced.
It is not always convenient to carry out a periodic operation to remove the sagging of the drive element, and in order to get rid of this procedure, motorists often install an automatic chain tensioner, which independently tightens as the chain loosens. The design features of such a device exclude the possibility of its wedging.
Design and operation of the automatic mechanism
This type of part is equipped with a ratchet mechanism, due to which the slack in the chain is removed automatically as it is stretched. The tensioner consists of a housing and a spring-loaded ratchet pawl located in it. It is also equipped with a spring-loaded toothed bar. The teeth on the bar are inclined to one side, and their pitch is one millimeter.
How it works
Depending on the degree of sagging of the chain, the spring of the mechanism acts on the toothed bar, and it, in turn, on the chain tensioner shoe. At the same time, the return of the bar to its original position is impossible due to the pawl of the ratchet device.
The dog gets between the teeth of the bar and does not allow it to move back. Thus, the spring constantly acts on the bar and tightens the chain, and the ratchet does not loosen.
Replacing the chain tensioner
You can make a replacement at home. Just enoughhave a set of tools and, accordingly, a new tension element. This device is located on the outside of the engine crankcase, under the water pump. For repair work, you will need locksmith yews and open-end wrenches for ten and thirteen.
Dismantling the device
We put the car on a flat surface and apply the parking brake. In order to remove the VAZ chain tensioner, you do not need to remove anything from the engine. It is enough just to unscrew the fixing nuts of this device and get it. When doing this, be careful not to damage the gasket.
Installing a new device
If the mechanism is a plunger type, then before installing it on the engine, you need to drown the plunger into the body.
To carry out this operation, the chain tensioners are carefully clamped in a yew. Then, with a wrench, loosen the lock nut by thirteen. After that, under the influence of the spring, the mechanism will move out of the housing. To push it back, the tensioner is taken out of the yews. Holding the part in hand, with the other hand we press the plunger inside the body and, holding it in this position, tighten the lock nut. After that, you can install the regulating mechanism on the engine. In order for the element to work and tension, loosen the nut and then tighten it.
Change the shoe of the VAZ chain tensioner ‘a
Changing the shoe is a little more difficult than the tensioner itself. Here, in addition to dismantling the mechanism itself, it is additionally necessary to remove the pulleys of the gas distribution mechanism drives located infront of the power unit.
Then it will be necessary to remove the protective metal cover of the drive, drive gears of the camshaft and the shaft of auxiliary mechanisms. Only after the dismantling work has been done, you can proceed to remove the shoe. Regardless of the type of engine power system, chain tensioners make no significant difference in terms of replacement.
Installation of automatic type tensioner
When deciding to replace the standard device with a more modern one, the removal of the first one should be carried out as described above. Using the example of the "seven", it can be noted that it is possible to install an automatic circuit adjustment device on the engine. The Pilot chain tensioner is very good for this. As a rule, this mechanism is sold already with a working rod inserted into the body, which has a fixation (pin) on the end side of the device. First you need to install an automatic device on the engine, which occurs in the same way as installing a standard regulator.
After installation, you need to pull out the lock pin with pliers, and the spring will press on the bar. Next, screw the bolt into the end of the housing, which prevents the spring from falling out. Often this bolt comes with a tensioner.
As you can see, the processes of replacing and installing various types of tensioners do not differ much in the sequence of execution, and you can repair the car yourself.
Previously, cars of this model were equipped with engines with tensioners, the design of which provided for the presence of a spring. These models are now equipped with hydraulic drive tensioners. The plunger rod of the device is driven by oil pressure. This type of device is also fully automatic and does not require human intervention to adjust the degree of tension on the flail.
But, like any part of the machine, the hydraulic chain tensioner (Niva is no exception) can become clogged and damaged during operation, and it will have to be replaced.
The removal process is carried out as on all VAZ cars up to the seventh model, with only one difference - the need to remove the hydraulic oil supply pipe, the supply of which is located at the end of the part. In order to prevent oil from leaking out of the pipe in the future, it must be plugged with a piece of rag or a suitable bolt.
It is important to note that after dismantling the part, it is worth checking for its further suitability, perhaps it is simply clogged. The oil that enters the tensioner can carry soot, elements of the production of metal and rubber parts, so the plunger rod may be wedged.
To clean, place the part in a small container of gasoline, let it soak for a while, then rinse thoroughly and dry with compressed air.
Check carefully the body and the plunger part of the mechanism for defects in the formscratches and dents. In the absence of such, we check the operability of the device. We take it in hand, and the second we try to move the plunger in the body. The plunger-rod should move smoothly and without various jams. If the movement of the plunger is difficult, repeat the flush again. When and after that nothing changes - replace it with a new one. Installation of the hydraulic part is carried out in the reverse order of removal.