2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:41
The car engine is equipped with two or more valves per cylinder. One is designed to let the fuel mixture into the cylinder. The other is used to release exhaust gases. In technical terms, they are called "inlet and outlet valves". The gas distribution mechanism of the engine sets the sequence of their opening at a certain point in the valve timing.
Due to the fact that the car engine, its parts and mechanisms are exposed to high temperatures, installation thermal gaps are provided on the valves of the gas distribution mechanism.
Misadjustment and consequences
When the thermal clearance of the valve changes during long-term operation or when individual elements of the system break down, the efficiency of the engine and the life of parts are significantly reduced. This is also accompanied by increased fuel consumption and a characteristic knock in the engine compartmentspace. If, for example, the gap is greater than the norm, the element cannot 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 have a bad effect on the reaction of the engine when you press the accelerator pedal.
Expert Tips
In order to encounter this problem less often, it is recommended periodically, approximately every 30,000 km of a car, to check what clearances are on the valves. Adjust if necessary.
Gap setting
To begin with, there are several important points to note when carrying out these repairs. Firstly, it is necessary to carry out adjustment only on a cold engine. Secondly, it is worth knowing that for different valves (inlet, outlet) there are different installation dimensions, the same applies to varieties of car brands.
There are also engines that do not need periodic clearance adjustment. This is due to the design of the gas distribution mechanism. The valves are actuated by hydraulic lifters, which, in turn, compensate for the gap using engine oil. At the same time, the service life of those is approximately 60,000 km, it all depends on the manufacturer and driving style. This review will provide detailed instructions on how to adjust the thermal clearances of the valves of VAZ engines and some foreign cars. To carry out this operation, it is additionally recommended to purchase a new valve cover gasket, sinceafter dismantling the cover, oil leakage from the gasket is possible in the future.
The gap is checked with a special measuring probe, the thickness of which must meet the technical requirements of a particular brand of car.
Adjustment process
Basically, the process of installing valves does not differ much depending on the engine and looks about the same.
First, you need to bring the piston of the cylinder on which the adjustment will be carried out to top dead center during the compression stroke. At this point, the intake and exhaust valves will be closed and their rocker arms should move radially within the set clearance.
Next, loosen the control nut on the adjustment screw. Install a feeler gauge between the camshaft cam and the valve end, and then use the adjusting screw to set the recommended clearance and lock the screw. When properly installed, the control probe should pass through the gap with little effort. If there is even the slightest discrepancy, you need to redo the setup procedure.
Having turned the crankshaft one hundred and eighty degrees, the operation should be repeated on the next cylinder. In this case, it is important to consider the order of operation of the car's engine cylinders.
Setting the gap on a VAZ "nine" car
The valve clearance of the VAZ-2109 is regulated by selecting and installing special shims. They are placed between the end of the valve and the camshaft cam.
Installing the necessarygap - the process is simple and quite executable, but it requires special care and a careful approach to business from the master.
Tools and fixtures
To carry out the work, you must have a number of tools and devices:
- Standard set of keys.
- Set of control probes.
- Adjustment washers set.
- Valve squeeze tool.
Direct process
First remove the valve cover. To do this, first dismantle the air filter housing, breather pipe and throttle cable.
In order to measure the gap between the valves of the cylinders, it is necessary to periodically scroll the crankshaft. And in order for it to scroll easily, it is recommended to unscrew all the spark plugs.
Next, remove the protective plastic timing belt cover. Then we scroll the crankshaft clockwise until the alignment marks on the camshaft gear coincide with the mark on the metal cover. It is recommended to turn the crankshaft by the nut of the generator pulley, using the key for seventeen.
After the moment the marks coincide, it is necessary to rotate the shaft by another three teeth of the timing belt.
After carrying out the preparatory work, you can measure the clearance of the exhaust valve on the first cylinder and the intake valve on the third. The optimum intake valve clearance should be two tenths of a millimeter with a maximum allowable error of five hundredths.millimeter. And for graduation it is 0.35 mm. When the actual clearances are not correct, then, using the tool, you need to pull out the washer, after lowering the piston to bottom dead center.
Next, the thickness of the required washer for installation is determined. From the measured value, you need to subtract the value of the recommended clearance, and add the size of the washer to the result. All washers are laser marked with the value of its thickness. In the event that for some reason the marking is poorly visible, you should use a micrometer.
What valve clearance should be set when adjusting is indicated in the car's service book.
In the future, with each revolution of the crankshaft one hundred and eighty degrees, the value of the gaps is measured: the fifth and second exhaust and intake valves, the eighth and sixth exhaust and intake, the fourth and seventh, respectively. After installing washers of the required size, the gap size is checked again.
Adjustment of thermal valve clearances on imported cars
Timely installation of the correct gap size is also necessary for imported car engines. As a rule, the adjustment process differs little from carrying out these operations on domestic engines. So, for example, on Honda cars, valve clearances can be set by hand, without the help of a specialist, using only a screwdriver and a wrench. As an exception, several rare power units can be calledmanufacturer, in which a hydraulic compensation system is used (C32A engines). In the rest of the engines of various 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.
Renault valve clearances
Before you - detailed instructions for self-adjusting the valves of the Renault Logan engine.
Unscrew the bolts securing the air filter housing and remove it. Dismantle the valve cover pipe. We remove the armored wires from the spark plugs and unscrew them one by one. Next, you need to 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 fourth gear. Next, rotate the front wheel until the F mark appears on the camshaft gear. It is important to monitor the valve of the first cylinder. Using a feeler gauge, we check the thermal gap, after loosening the locknut of the set screw. After the gap is set, tighten the locknut and re-measure. After that, we proceed to adjust the second element of the same cylinder.
Next, turn the crankshaft half a turn and adjust the valve clearance on the third cylinder. The installation of elements on the fourth and second cylinders is carried out in the same way.
After the work, we carry out control measurements. We rotate the crankshaft three hundred and sixty degrees and check the clearances of all valves.
According to specificationsengine characteristics, the installation standards have the following indicators:
- Inlet valves - 0, 1-0, 15 mm.
- Graduation - 0.25-0.3 mm.
In the case of a complete replacement of the exhaust valves, special grinding gaps are provided - 0.2-0.25 mm.
Adjustment procedure on the motor ZMZ-402
The valve clearances of the 402nd engine are set approximately the same as on other cars.
First of all, you need to turn the crankshaft clockwise, set the piston of the first cylinder to TDC (compression stroke) and match the pulley and cover marks. In this case, the valves must be closed. First, we adjust the outlet. Its gap should be 0.35-0.4 mm. The intake valve clearance should be 0.4-0.45 mm. After working with the first cylinder, we move on to the second. Don't forget to turn the crankshaft half a turn.
Next, we work with the fourth and third cylinders, first turning the crankshaft each time.
At the end of the work, we make control measurements, if necessary, we make adjustments. Install the valve cover gasket and the valve cover itself. This completes the operation.
Result
If the repair process is carried out correctly, the car's engine will be more responsive, 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 elementstiming system, 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 figured out how to independently adjust the valves on the car.
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