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Timing Chain ZMZ-406: installation and replacement

The gas distribution system is one of the main components of any engine. It includes a chain or belt transmission. The latter is less noisy, but at the same time less reliable. The chain never breaks. But at work can make sounds. Today we will look at how the timing chain ZMZ-406 is replaced and what is this element.

Characteristic

This part is the basis of the engine. It is thanks to the chain that the phases of the timing belt ZMZ-406 can be correctly set. Recall, this is the intake, compression, working stroke and release. In order not to bend the valves and ensure the maximum efficiency, a special chain is used.

It is she who distributes the forces on the camshaft, which opens and closes the engine valves at the right time. Thus, the timing system ZMZ-406 ensures the timely supply of a combustible mixture to the combustion chamber and their output after the third stroke (working stroke). As a result, we get a powerful and economical engine.

Where is?

The timing chain ZMZ-406 is located on the crankshaft pulley. It rotates simultaneously with it when the engine is running. Also used special silencers chain timing ZMZ-406. They provide the necessary tension of the mechanism.

If it becomes unusable, the installation of the ZMZ-406 timing phases will be incorrect. The chain will stretch or skip a few teeth. During the operation of the mechanism, a water pump, a hydraulic amplifier (not all "gazelles") and an intermediate shaft of the ignition system are activated. With each of these elements, the timing chain ZMZ-406 is closely connected.

About faults with timing

The main signs of a breakdown are a reduction in engine power, characteristic claps in the exhaust and intake manifold, as well as a low level of compression. It should not be less than 10 kilograms per square centimeter. But it is not necessary to buy a new set of timing ZMZ-406. Perhaps, only the chain went out of action. By the way, she with a malfunction publishes metal knocks. Such malfunctions of the timing of ZMZ-406 can be caused by a loose fit of valve seats. As a result, carbon deposits are formed, valve springs fail. The clearance between the rocker arm and the valve stem is not normal. If the engine does not provide sufficient opening of the valves, this may cause damage to the hydraulic compensators. The crankshaft and camshaft gear are also worn out. As a result, it is necessary to repair the engine ZMZ-406. The timing is a serious mechanism. In order to avoid trouble, it is necessary to monitor the tension of the chain and regulate the silencer. This must be done at least once every 80 thousand kilometers. The chain, in contrast to the belt - a fairly reliable mechanism. It does not tear and does not provoke the bend of the valves, but only stretches during prolonged use. The resource of the gas distribution chain is about 200 thousand kilometers. The belt does not exceed 80 thousand. But if you have characteristic symptoms on 150 thousand (referring to the metal knocking of the chain), do not hesitate to replace. Below we will consider how to repair this system with your own hands.

Instruments

To replace the timing of ZMZ-406 successfully, we need to prepare a set of tools. We need a set of heads and hex keys, a torque wrench, a hammer and a chisel. Next, consider the step-by-step process of replacing the timing chain ZMZ-406.

Preparatory work

To begin with, we need to prepare containers for draining working fluids. First we pour out the antifreeze. In "GAZelle" it contains a lot, about ten liters. It is fused by unscrewing the plug in the bottom of the radiator. Be careful - at first the antifreeze will run in great pressure. As the pouring out, it will be less. It is recommended to use a bulky canister or a bucket. It is important that the container is clean. For a better exit of antifreeze, we unscrew the lid on the expansion tank.

What next?

After that, we take off the front apron with the radiator grille (if this is a "business" bumper, unscrew its mounts in the center and on each side). Next, remove all the clamps and nipples that are fed to the radiator. Dismantle the last element. If your vehicle is equipped with a hydraulic booster, you must remove the GUR pump drive belt.

Also we take out the belt of the generator and the pump, after loosening the tension. Now remove the cylinder head cover. All bolts need to be folded into a separate box or niche. This does not affect the repair in any way, but will significantly speed up the build process. You do not have to look for where the missing bolt or nut lies, as is often the case. Further we twist viskomuftu fan with the impeller itself.

It is recommended to put the valve cover in a clean and dry place. The presence of dust on its inner side is highly undesirable. Next, the pump and the crankshaft rotation sensor are removed (do not forget to replace it, otherwise you just do not start the engine). At the next stage, the crankshaft pulley and the oil pan are dismantled. Then unscrew the two fastening bolts of the chain tensioner. The last element goes to the outside. In total, on the 406th and 405th motor, the two hydraulic pullers are upper and lower. We need to get both mechanisms. The bottom is sorted by the same principle. Next, we need to remove the chain cover. It is attached to seven bolts. Be careful - you can damage the front crankshaft seal and the cylinder head gasket. We unscrew a bolt of the top натяжителя and we remove the lever with an asterisk. Further we unscrew the plastic silencer of the timing chain ZMZ-406. We unscrew the bolts that fasten the gears to the camshaft flange (there are two of them in this motor). Next we need another tool. To remove the lower gear, it is necessary to install a minus screwdriver (it will serve as a lever) between it and the second gear.

Bend the end of the lock plate, and, while holding the intermediate shaft, insert our tool. We take out the gears and the lower part of the chain from the crankshaft. If there are difficulties with dismantling, you need to remove the rubber seal between the gear and the bushing. The last element is also dismantled. The second gear is pressed using a puller.

After the chain was removed

So, we get the element out. The chain must be thoroughly rinsed in gasoline and cleaned of dirt. Examine her external state. After 150 or more thousand kilometers, it is stretched to 1-2 centimeters. This is enough to provoke an incorrect gas distribution. If there are signs of wear on the hubs of the mechanism, scuffing and cracks, the mechanism can not be further operated. If the gears are chipped, they also change to new ones. Inspect the condition of the depressants. If damaged, replace the element with a new one. Check the correctness of the tensioner sprockets. They should rotate freely on their own axis. Scuffing and chipping on the working surface should not be.

Reverse Assembly

First, it is necessary to correctly establish the valve timing. To do this, scroll the crankshaft until the first mark on it coincides with the second on the cylinder block. The piston of the first cylinder must be in the top dead center position. Next, install the chain stabilizer. Do not screw the bolts yet. Lubricate the lower chain with engine oil and put it on the driven gear and crankshaft. The penultimate set so that the pin enters the hole of the intermediate shaft. The mark on the gear must match the one on the cylinder block. At the same time, the part of the chain that passes through the soot is stretched. We twist fixing bolts of gear wheels of an intermediate shaft. A locking plate is installed under them.

It is recommended to use a torque wrench. Tightening torque is from 22 to 25 Nm. When the bolt is tightened with the right moment, this key starts to click - go to the second element. Do not forget to lock both bolts with the lock plate. Its edges are bent with a hammer and a chisel. Then click on the tensioner lever and check whether the marks on the cylinder block and on the gear wheel have coincided. We tighten the bolts of the silencer and lubricate the upper chain. We put it on the intermediate shaft gear. Scroll the camshaft clockwise. We put the chain on the second gear. The camshaft pin must enter into its hole.

Moments of charging and tags

Using a square key, scroll the camshaft counterclockwise. Tighten the timing chain. The crankshaft and the intermediate shaft must not rotate. The labels will coincide with the upper surface of the cylinder head. From the exhaust camshaft, remove the gear and install a chain on it. Then put it back, slightly rotating the shaft clockwise. The pins must enter the pinion hole. Rotate the shaft counterclockwise, pulling the timing chain. Then, the chain cover and pump are installed. On the top of the cover, apply a small layer of sealant. When installing, do not damage the front crankshaft seal. Then, two hydraulic pullers and a crankshaft pulley are mounted. At the latter it is necessary to observe the tightening torque - from 104 to 129 Nm.

Thus it is necessary to include 5 transfer and a lay brake. Hold the crankshaft so that it does not rotate. Then the ratchet is tightened. The latter is rotated by two turns. The crankshaft is set to the position of the top dead center (relative to the first cylinder). Then install the cylinder head cover. On it it is necessary to put a layer of sealant in order to avoid oil leaks. The cover is tightened to a torque of about 12 Nm. Then it is necessary to connect a branch pipe of ventilation of crankcase gases to the union on the valve cover. We connect wires to ignition coils and put their ends on candles. Fill back the antifreeze, put the radiator in place and start the engine. If everything was done correctly, the metal sounds will be lost, and the engine power will return to normal. This is the process of repair of the gas distribution mechanism is completed. The best timing ZMZ-406 is the one that is on the chain. To the belt drive, many car owners are still skeptical. Chain drive at times more reliable. But practice shows that every year it loses popularity, especially among foreign manufacturers.

Installation problems

There have been cases when the repair of this mechanism damaged the head gasket of the unit. In this case, it is necessary to cut off its remains with a clerical knife and use a sealant. Also, this means must be treated with all the sealing parts of the cover. The drying time of the sealant is 24 hours.

Conclusion

So, we found out what the gas-distributing mechanism on the "GAZelevsky" 406th motor is. As you can see, replacing the chain does not require the presence of additional tools. But in time it takes all day. Therefore, it is worthwhile to plan such repairs in advance. At the SRT, this service takes about 5 hours. The cost of it is six thousand rubles. The same set of gas distribution mechanism costs about five thousand. It includes chains (small and large), hydraulics, calipers and sprockets of camshafts.

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