Valve clearance: what should it be? The instruction on correct adjustment of valves VAZ and foreign cars

The engine of the car is equipped with two or more valves per cylinder. One is designed to let the fuel mixture into the cylinder. The other serves for exhaust gases. Technically speaking, they are called "inlet and outlet valves." The gas distributing mechanism of the engine establishes the sequence of their opening at a certain moment of the gas distribution phases.

In view of the fact that the engine of the car, its parts and mechanisms are exposed to high temperatures, the valves of the gas distribution mechanism are provided with installation thermal gaps.

Regulation and consequences

When the thermal gap of the valve changes during a long operation or if the individual components of the system fail, the efficiency of the engine and the life of the parts decrease noticeably. Also, this is accompanied by increased fuel consumption and a characteristic knock in the engine compartment. If, for example, the gap is more than normal, the element can not open completely, and this contributes to a drop in power characteristics. Burning of the valve and its seat is possible in the case of a very small gap. In any case, these malfunctions do not work well on the reaction of the engine when the accelerator pedal is depressed.

Advice of specialists

To rarely encounter this problem, it is recommended that periodically, approximately every 30,000 km of the car run, check what gaps are on the valves. If necessary, they should be regulated.

Setting the clearance

To begin with, several important points should be noted when carrying out these repairs. Firstly, adjustment is only necessary on a cold engine. Secondly, it is worthwhile to know that for various valves (inlet, outlet) there are different installation dimensions, the same applies to varieties of car brands.

Also there are engines that do not need periodic adjustment of the gaps. This is due to the design of the gas distribution mechanism. The valves are activated by means of hydraulic compensators, which, in turn, compensate for the gap by means of engine oil. At the same time, the service life of those is about 60 000 km, all depends on the manufacturer and the manner of driving. In this review, the instruction on how to adjust the thermal gaps of the valves of VAZ engines and some foreign cars will be presented in detail. To perform this operation, it is additionally recommended to purchase a new valve cover gasket, since after removing the cover, it is possible later to leak oil from the gasket.

The gap is checked by a special measuring probe, the thickness of which must correspond to the technical requirements of a certain car brand.

Adjustment process

In general, the process of installing valves is not very different depending on the engine and looks about the same.

To begin with, it is necessary to bring the piston of the cylinder on which the adjustment will be performed to the top dead center during the compression stroke. At this point, the inlet and outlet valves will be closed, and their rockers will move radially within the specified clearance.

Next, release the control nut on the adjustment screw. Install the dipstick between the camshaft cam and the valve end, and then use the adjusting screw to set the recommended clearance and touch the screw. If properly installed, the test probe must pass through the gap with little effort. If there is even the slightest discrepancy, you need to re-run the setup procedure.

Turning the crankshaft to one hundred and eighty degrees, you should repeat the operation on the next cylinder. It is important to consider the order of operation of the engine's cylinders .

Installation of the gap on the car VAZ "nine"

Valve clearance VAZ-2109 is regulated by selection and installation of special adjusting washers. They are placed between the end part of the valve and the camshaft cam.

The installation of the necessary clearance is a simple and fully executed process, but requires the master to be very attentive and carefully approach the matter.

Tools and accessories

To carry out the work, it is necessary to have a number of tools and adaptations:

• Standard set of keys.
• Set of control probes.
• Set of washers for adjustment.
• The device for squeezing valves.

The process itself

First remove the valve cover. For this purpose, we first dismantle the air filter housing, the breather hose and the throttle actuator cable.

In order to measure the clearance between the cylinder valves, it is necessary to periodically crank the crankshaft. And that it easily scrolls, it is recommended to unscrew all spark plugs.

Then remove the protective plastic cover of the timing belt. Then scroll the crankshaft in the clockwise direction until the timing marks on the camshaft gear coincide with the mark on the metal cover. It is recommended to rotate the crankshaft for the nut of the generator pulley, using the key for seventeen.

After the moment of coincidence of marks it is necessary to turn a shaft on three more prongs приводной a belt of the mechanism газораспределения.

After carrying out the preparatory work, it is possible to measure the clearance of the exhaust valve on the first cylinder and the intake valve on the third cylinder. The optimal clearance of the intake valves should be two tenths of a millimeter with a maximum permissible error of five hundredths of a millimeter. And at the graduation he is 0.35 mm. When the actual gaps do not correspond to the norm, then using the device, it is necessary to pull out the washer, before lowering the piston to the bottom dead center.

Next, the thickness of the required washer is determined. From the measured value it is necessary to take away the size of the recommended gap, and to add the size of the washer to the result. All washers are laser marked with a value of its thickness. In the event that, for some reason, the marking is poorly seen, you should use a micrometer.

The way in which the valve clearance should be set during adjustment is indicated in the car service book .

In the future, with each revolution of the crankshaft at one hundred and eighty degrees, the values of the gaps are measured: the fifth and second exhaust and intake valves, the eighth and the sixth exhaust and intake, the fourth and the seventh, respectively. After installing the washers of the required size, the gap size is checked again.

Adjustment of valve thermal gaps on imported cars

Timely installation of the correct size of the gap is necessary for engines imported from foreign manufacturers. As a rule, the adjustment process differs little from carrying out these operations on domestic engines. So, for example, on Honda cars, valve gaps can be installed with your own hands, without the help of a specialist, using only a screwdriver and a wrench. As an exception, we can name several rare power units of the manufacturer, in which the hydraulic compensation system is used (C32A type engines). In the remaining engines of different series (B16-18-20, D13-14-15-16-17, R18-20, ZC and others), repairs are carried out quite simply and without the use of additional equipment and equipment.

Valve clearances "Renault"

Before you - a detailed instruction for self- adjusting the valves of the engine "Renault Logan".

We unscrew bolts of fastening of the case of the filter of air and we remove it. Dismantle the valve cover. We remove the armored car with the spark plugs and twist them alternately. Next, unscrew the bolts of the valve cover and carefully remove it. Then, using a jack, you need to hang out the front of the car and turn on the fourth gear. Then rotate the front wheel until the mark F on the camshaft gear appears. It is important to monitor the valve of the first cylinder. Using the probe, we check the thermal gap, first loosening the lock nut of the setscrew. After the clearance has been established, tighten the locknut and repeat the measurement. After this, proceed to adjust the second element of the same cylinder.

Then crank the crankshaft half turn and adjust the valve clearance on the third cylinder. In the same way, the installation of the elements on the fourth and second cylinders is carried out.

After carrying out the work, we perform control measurements. We rotate the crankshaft to three hundred and sixty degrees and check the gaps of all the valves.

According to the technical characteristics of the engine, the installation rates have the following indicators:

• Valves inlet - 0,1-0,15 mm.
• Graduation - 0,25-0,3 mm.

In the case of a complete replacement of the exhaust valves, there are special clearance gaps of 0.2-0.25 mm.

The order of adjustment on the engine ZMZ-402

Valve clearance of the 402 engine is set approximately the same as on other cars.

The first thing to do is to rotate the crankshaft clockwise, put the piston of the first cylinder in the TDC (compression stroke) and match the pulley and lid marks. In this case, the valves must be closed. First we adjust the outlet. Its clearance should be 0.35-0.4 millimeters. The clearance of the intake valve should correspond to 0.4-0.45 millimeters. After working with the first cylinder, go to the second one. Do not forget to turn the crankshaft half turn.

Further we work with the fourth and third cylinders, preliminary turning crankshaft each time.

At the end of the work we make control measurements, if necessary, make a adjustment. We establish a lining of a cover of valves and a cover in place. This completes the operation.

The result

If the repair process is properly carried out, the engine of the car will be more pristine, the characteristic noises from under the valve cover will disappear, and fuel consumption will decrease. The resource of the gas distribution mechanism will increase significantly. Also, to prevent damage to the timing components, it is necessary to monitor the degree of tension of the camshaft drive belt. In this case, the power unit will last much longer than its life.

So, we found out how to independently adjust the valves on the car.