Hydraulic chain tensioner: device and operating principle

As you know, the engine of the car uses a belt or chain drive gas distribution mechanism. The latter type appeared a little earlier and is considered the most reliable. But recently the chain becomes irrelevant to foreign producers. But while domestic "GAZel" and "Niva" (including the "Chevrolet Niva") are equipped with this type of drive. In today's article, we will look at the timing chain hydraulic tensioner , its operation principle and the replacement order.

Characteristics of the mechanism

This element performs the function of adjusting the chain tension in the timing gear. It is installed on all cars with this drive. The chain tensioner compensates for weak tension. Over time, the part wears out. The chain constantly rotates while running the motor and has the property of stretching. It comes to the fact that the piece jumps on one or more teeth. As a result, an incorrect gas distribution occurs. As a consequence - the later or early closing of the intake and exhaust valves. Stretching the chain is quite normal. For its lifetime, it can be stretched by one to two centimeters. The chain tensioner smoothes this tension.

Device

This node consists of several parts:

• Valve bodies.
• The locking ring.
• Plunger.
• Springs.
• Locking ring.

Also, the chain tensioner ("Niva Chevrolet" is no exception) has a hole for the supply of oil.

How does it work?

The principle of operation of the element is based on the operation of the spring. When the oil from the line comes through the valve body, the plunger presses on the plastic tension shoe. Some engines use a lever with an asterisk. In this way, the surface of the working element is in continuous contact. When the engine speed changes, the element's plunger moves back. The spring contracts. Vibration damping occurs due to the flow of lubricant through the plunger and the housing. The pressure of the oil is controlled by the ball valve of the hydrotensioner. When the chain is pulled out, a plunger extends from the housing. The retaining ring moves along the grooves, ensuring proper tension. Also, the unit compensates for thermal elongations, which are formed as the engine warms up.

How to check the chain tensioner?

It is necessary to control the appearance of new knocking in the engine compartment. If shocks were found in the cylinder head cover, this indicates a malfunction of the tensioner. These sounds are clearly audible when the accelerator pedal is abruptly reset. What are the reasons for the fact that the hydraulic puller of the chain of the 406th engine has become unusable? This can be wedged plunger and breakdowns in the ball valve, which causes a mismatch in the oil pressure. Also, the plastic shoe (or an asterisk, if any) and the soot wear out.

Where is he located?

This element is located in the engine compartment on the left side. It is necessary to find cooling tubes in the front part of the cylinder head - underneath it there is a hydraulic puller of the chain.

How to change?

If the above symptoms are observed, an urgent replacement of the chain tensioner is necessary. To do this, we need a new element, as well as a set of heads. Using a key for 10, unscrew the pipe union of the cylinder head and remove it. Further we find two fixing nuts of the tensioner. We unscrew them with the same key. We take the protruding part of the mechanism with our hands and remove it from the seat. It should be noted that the chain tensioner has its own gasket, which must also be replaced. Before installing a new element, carefully smear the seats with silicone sealant. Install the gasket and tighten the bolts. By the way, before installation it is necessary to remove the transport stop. This element is needed to prevent the tensioner from discharging (so that the plunger does not come out of the housing) when transporting it. To "charge" the element and bring it into working state, after assembling it is necessary to press a minus screwdriver on the part with great effort. As a result, the body of the hydraulic tensioner under the action of the spring will move to the cover until it stops. The plunger itself will produce the proper tension of the chain through the sprocket or shoe (depending on the engine's design features). Before "charging" you need to tighten all bolts carefully. Otherwise, this will lead to premature wedging of the element. Do not forget to install the union again. After installation, start the engine and check it for extraneous sounds.

What if the replacement did not help?

It happens that knocking does not go away after replacing the tensioner. In this case, it is necessary to check the length of the circuit itself. After 150 thousand kilometers it can stretch out so much that even a new tensioner can not compensate for this. Therefore, when this mileage is reached, the chain also changes.

Is it possible to repair the old one?

The old hydraulic chain tensioner can be repaired in 60 percent of cases. But first you need to make sure it's faulty. To do this, press the finger onto the spherical end of the element. If it is not pressed, then the tensioner is jammed. This is due to the skewing of the locking ring. At the ends of the cut, it has small burrs. They interfere with the work of the element. The disassembled tensioner must be thoroughly rinsed in kerosene and replaced with a locking ring. Its outer diameter is 16.6 by 3 millimeters. The ring can be made of spring wire. It happens that the ball valve goes out of order - it lets in excess oil. To check its tightness, it is necessary to take out the plunger and the spring from the housing. Insert the last end (spherical) part into the opening of the body. Push your finger against the opposite end of the element. If there are large traces of oil leakage, the part must be replaced. From the plant, small emissions are allowed through two risks on the end part of the tensioner body. They serve to remove air from the insides of the mechanism. You can try to rinse the element, thereby restoring it. But the result is not always effective. To do this, it is necessary to rinse the ball valve in gasoline or kerosene, pressing it with a thin wire through the oil hole. If the flushing has not yielded results and the element still passes oil, it should be replaced.

Manual chain stretching

To eliminate the characteristic knock of the chain drive in the area of the valve cover, without changing the element itself, you can manually pull the part. Let us consider how this procedure is performed using the VAZ-2106 car as an example. Here we use an asterisk in the tensioner. So, first you need to remove the air filter with the body and the casing. Further we twist the tensioner (not to the end) and produce 2-3 turns of the crankshaft. You can do this with a regular key, setting it to the third position. After several rotations of the crankshaft, a chain drive is activated. Then check the level of its tension by pressing your finger on the links. It should not sag at two or more centimeters. With the proper tension of the chain, the hydraulic tensioner is twisted and the attachments assembled in the reverse order. This procedure must be repeated at every occurrence of knocking under the hood.

Price

The cost of this element is from 500 to 900 rubles. In the absence of time for repairs, you can limit yourself to buying a new tensioner assembly.

Conclusion

So, we have found out the device and a working principle of a hydrotensioner of a chain. Remember that driving with knocks under the hood is fraught with engine damage. If the chain is stretched, it begins to vibrate. The phase of the gas distribution is violated. Watch the regulations for the replacement and listen to the work of your engine.