The timely supply of the engine with a combustible mixture and the release of gases from the cylinders are the functions of the valve timing mechanism. In all VAZ models, except VAZ-2105 and VAZ-2107, chain drive mechanism (Fig. 9). In addition to chain 2, the drive includes: steel drive sprocket 4 of the crankshaft, driven sprocket 1 of the camshaft, tensioner shoe 5 and chain damper 3.
To ensure normal operation of the gas distribution mechanism during operation, adjust: chain or drive belt tension; clearances between the cams and the valve drive levers. The chain is tightened to partially eliminate the noise it causes. We say "partially" because it is impossible to completely eliminate the noise, and reducing it by over-tightening the chain will only lead to intensive wear.
To tension the chain, you will need a starting handle and a key for the cap nut 6 of the tensioner. A few words about the key: the plant recommends using a 13 mm wrench. In practice, it has been established that this is not the most convenient key for this operation. Unscrewing the cap nut is significantly simplified if you follow the example of some Moscow service stations and make a special key (Fig. 10). By the way, it is successfully used when removing the cylinder head cover and adjusting the door locks.
The chain tension adjustment process must be performed in the following order: with a special key (or a 13mm wrench) loosen cap nut 6 of tensioner 5; use the starting handle to turn the crankshaft 1-1.5 turns.
The tensioner springs, acting on the shoe, will automatically set the correct chain tension. Then tighten the cap nut 6. Having completed the operation, pull out the starting handle. It is advisable to perform this operation with the cylinder head cover removed. In this case, the chain tension can be checked by pressing with your finger with a force of 49.04 N between the sprocket and the chain damper 3. The chain should bend by 4-5 mm.
Sometimes, after adjustment, a strange clicking sound appears on a hot engine. This is the tensioner rod touching the bottom of the cap nut 6. Unscrew the nut on a non-running engine, remove the collet clamp and ring, put a washer 0.2-0.3 mm thick and 16 mm in diameter under the clamp. The mechanism assembled with an additional washer will not knock. If you do not provide the necessary tension, the chain will make increased noise. Moreover, it can break the damper. It happens that a poorly tensioned chain acquires a special "agility" and jumps over the teeth of the camshaft gear. As a result, a "failure" in the valve timing phases occurs, and the engine fails to work.
You need to get used to the rustling noise of the valve timing mechanism. At first it is disturbing, it seems criminal, but it is a specific noise of the chain drive. However, it should not increase. An increase in noise is a signal to take action.
On VAZ-2105 and VAZ-2107 cars, the belt tensioning operation is also simple. Remove the protective cover and loosen the bolts securing the rotary plate 10 (see fig. 7) tension roller 11. When turning the crankshaft [to simplify the operation, it is advisable to make a key (Fig. 11)] two or three turns, spring 3 itself, without anyone's help, will tighten belt 5. It remains to tighten the bolts and install the cover.
The chain with the tensioner is only the drive of the valve timing mechanism itself (Fig. 12), which performs the functions of the distributor of the combustible mixture. In order for the fuel injection and gas exhaust process to proceed normally, there must be some gap A between the lever 6 and the cam 1. This condition is mandatory, since the valves operate at high temperatures and, naturally, increase in size. These gaps are subject to checking and adjustment. If the gap is large, i.e. more than 0.15 mm, the valve begins to knock. It is not difficult to determine this knock, since its frequency is less than any other knock (the valves are driven by the camshaft, which rotates 2 times slower than the crankshaft). There may be no knocking, but adjustment is still needed. This happens when the valve is "clamped", i.e. the gap is less than 0.15 mm.
As you can see, valves require normal clearances, otherwise compression decreases, valves burn out, become deformed, the engine does not develop power, loses throttle response, runs unstably and overheats.
It is not difficult to learn how to adjust the valves yourself, you only need attention, accuracy and skill. When performing the operation, you will need: a special key measuring 17X17 mm, the peculiarity of which is that the head of the key is located at an angle of 45° and this eliminates the possibility of damaging the breaker-distributor when adjusting the gaps of the first and second valves; 8mm tubular wrench (or a special key shown in Fig. 10); screwdriver; pliers, wrench size 17 mm; a runner angle measuring device made from an old breaker cover. Remove the breaker-distributor cover without pulling out the wires from it, and install the runner angle measuring device in its place. The contacts on the inside of the device, located at 90° intervals, serve as marks against which the rotor plate should be stopped when turning the crankshaft.
The clearances must be adjusted on a cold engine (at a temperature not exceeding 20°C). While the engine is cooling down, you can dismantle anything that will interfere with the operation. To prevent anything unnecessary from getting into the carburetor, it is advisable to cover the carburetor inlet necks with a sheet of paper or cardboard, putting it on the studs. When removing the cylinder head cover, do not apply much force, but rather, lift it with one hand and push it slightly forward with the other in the direction of the car.
You can start adjusting the clearances only after you have determined in which cylinder the piston is at the top dead center. If you use the starting handle or key (see fig. 11) for VAZ-2105 and VAZ-2107 cars, turn the crankshaft to a position where marks A and B (Fig. 13) coincide, then at this point the piston of cylinder IV will reach the top dead center. This is where you should start. You can adjust it using feeler gauges 0.14 and 0.16 mm thick or using special devices produced by the domestic industry.
At present, thanks to the ingenuity of individual car enthusiasts, several methods of adjusting valve clearances have become widespread and are recognized by specialists. Traditional feeler gauges are beginning to give way to indicators, special rulers, etc. The industry has already mastered the production of new devices for these purposes (Etalon, URZ-01, etc.), but the sequence of adjustment remains the same regardless of the method and measuring devices.
So, the first clearances to be adjusted are the clearances of the exhaust valve of cylinder IV and the intake valve of cylinder III (see fig. 13 pos. 1). Holding the head of the adjusting bolt B with one key, loosen the lock nut G with the second (curved) one. A 0.14 mm thick feeler gauge should go in and out between the lever and the cam. By screwing the adjusting bolt B in and out, achieve the required clearance. If you are satisfied with the adjustment, fix the position of the adjusting bolt by tightening the lock nut. After this, be sure to recheck the clearance.
To move to the valves of the next cylinder, the crankshaft must be turned by 180°. A device for measuring the runner rotation angle will come to the rescue here. To facilitate this operation for VAZ-2105 and VAZ-2107 engines (fix the exact angle of rotation of the crankshaft) it is possible, using the advice of a car enthusiast from Donetsk, who suggested marking the camshaft pulley, starting from the factory mark, every 10.5 teeth. Considering that the number of teeth on the pulley is 42, such marking significantly simplifies the installation of the crankshaft during the adjustment process.
Many car enthusiasts prefer to use the most modern methods of adjusting clearances and successfully master the devices (Fig. 14). Experience, however, shows that when adjusting with an indicator, the readings of the latter are not always stable. The reason: the ability of the lever (rocker) to move in the longitudinal direction. A number of proposals have been put forward on how to eliminate the effect of the unstable position of the lever. One of them is as follows: after installing the device, loosen the lock nut 3 (see fig. 12), if necessary to eliminate the skewing of the growl, unscrew the adjusting bolt 2 until the levers and cam 1 stop; loosen the bolt until a guaranteed gap of 0.01-0.02 mm appears; set the indicator scale to 0; tighten the adjusting bolt until the indicator shows a value of 0.5 minus the guaranteed clearance of 0.01-0.02 mm; in this position I tighten lock nut 3.
It should be remembered that the Volga Automobile Plant managed to slightly change the shape of the lever, due to which car enthusiasts will experience certain difficulties when adjusting the clearances on the first and eighth valves. The adjustment can be made easier if the 17 mm diameter hole in the device bar (Fig. 14) is drilled to a diameter of 18.5 mm and the indicator leg is slightly bent.
The second thing we will adjust is the clearances of the exhaust valve of cylinder II and the intake valve of cylinder IV (see fig. 13 pos. 2), then after the next turn of the crankshaft, the clearances of the exhaust valve of cylinder I and the intake valve of cylinder II (pos. 3). The operation will be completed by adjusting the clearance of the exhaust valve of cylinder III and the intake cylinder I (pos. 4). In order to avoid mistakes, you can use the diagram of the sequence of valve adjustment when turning the crankshaft (Table 2).
Once the adjustment is complete, all removed parts must be reinstalled.
Particular attention should be paid to the cylinder head cover gasket. If the gasket has dents, cracks or tears, then there is no point in installing it, since oil leakage from under such a gasket is inevitable. The new gasket should be carefully placed in place and, when installing the cover on it, make sure that the gasket does not protrude from under the flange. The gasket is rubber.
If it is pressed evenly from all sides, it will provide reliable tightness. Uniformity of efforts during tightening can only be provided by a torque wrench. The Rigaselmash plant has mastered the production of these wrenches. Buy the DK-25 wrench.
Remember that performing operations such as tightening the cylinder head, installing the camshaft bearing housing, etc., is simply impossible without a torque wrench.
When returning the parts to their place, pay attention to the condition of the various pipes, tubes and hoses put on them. All of them should be free of burrs, torn edges and folds.
The air filter should not be ignored. It should be remembered that the air filter element is not eternal. It performs important rough work and over time becomes clogged with dust and dirt. A dirty filter begins to do more harm than good. Not only is it unable to clean the sucked-in air, but it also does not provide the carburetor with the required amount of air. The intensity of contamination depends on the operating conditions. If the filter element serves 10-15 thousand km when driving on asphalt, then on dusty dirt roads it becomes clogged faster. Inspect the filter and replace it with a new one if necessary.
If there are no air filters on sale and its condition is unsatisfactory, proceed as follows: remove the contaminated filter material from the plastic frame and install a "sipron" type material on the frame instead, which is widely used in various filters.
There are red and blue marks on the air filter housing cover. They have a specific meaning. These marks and the relief arrow on the housing are used for seasonal adjustment of the air filter. The blue mark means summer, and in this case fresh outside air enters the filter. With the red mark, which means winter, the filter receives air preheated by the exhaust manifold. After installing the filter element, position the cover so that the mark corresponding to the season is opposite the arrow.
Before installing the parts removed from the engine during valve adjustment, it makes sense to perform another very important operation: tighten the cylinder head mount. The plant recommends performing this operation twice: after 2 and after 5 thousand kilometers. It is during the first thousand kilometers that, as a result of multiple temperature changes, the tightness of the aluminum alloy head fits the cast iron block. The iron-asbestos gasket installed between them is somewhat compressed, so this three-layer composition requires tightening.
What does the weakening of the tightness between the cylinder head and the block itself lead to? The tightness of the cooling and lubrication system is broken, the antifreeze leaks, gets into the engine crankcase, the oil loses its properties, etc. Tightening of the cylinder head mount should be done on a cooled engine and, most importantly, with a torque wrench.
The head is secured with ten main bolts and one additional bolt, and they must be tightened according to a specific pattern and in two steps, as specified in the vehicle's operating instructions. All ten main bolts are tightened to a torque of 112.8 N·m. Bolt A (see "Operating Instructions") is tightened to a torque of 37.3 N·m.
If possible, make the key shown in Fig. 15, and when tightening the cylinder head there will be no need to remove the camshaft bearing housing.
Having finished working with the gas distribution mechanism, move on to the ignition breaker-distributor.
The information is posted on the portal [VAZbook]