How to check the crankcase gas valve?

If the UCSG in the engine is not working correctly, then it can deliver more problems to the car owner. In the ICE crankcase, the force of the gas pressure increases , because of which the oil is squeezed out from under the gaskets. Gases will look for any cracks to come out. Therefore, oil will also flow from the omentum. In order to allow gases to escape from the engine block, so-called forced ventilation systems are used in modern cars. Here, through rarefaction, gases are sucked into the intake path, and then they enter the combustion chamber, where they are burned. The crankcase gas valve is responsible for this. Sometimes it has various malfunctions that affect the efficiency of the power unit.

The classic scheme of the crankcase ventilation system

It's quite simple. The cavities of the motor are connected to the intake manifold. Due to the resulting discharge effect, the gases in the crankcase are sucked into the intake manifold. Afterwards, they enter the combustion chamber. One of the elements of the system is the crankcase gas valve. It is directed only in one direction, therefore gases can move only in one direction. They can not get back into the motor cavity. The system of ventilation of gases according to the principle of operation resembles a breather, which is available in the design of the transmission and in the bridges of the car. However, if in the transmission mechanisms the HF is opened, thereby releasing the gases into the environment, then in the engine they are discharged much better in the power unit due to the discharge. One of the examples is the engine ZMZ-24. It used an open-type ICGS. Gases could escape into the atmosphere through a special tube that was in the lid of the pusher. Since 1977, this system has gone and began to use a forced ventilation system. It was a closed type. Through a special hose that came from the engine's valve cover, the gases came out under the carburetor. Due to the introduction of such a solution, the release of harmful and dangerous substances into the environment has decreased. It was possible to seriously reduce the level of pressure inside the crankcase. This allowed to solve the problems with squeezing the stuffing boxes and gaskets. The engine was short of air, the power of the power units increased. The classical scheme of the UCSG provides for two types of mechanisms for the removal of gases - this is a direct flow and forced. An example is a system running on ZMZ-402. On this engine, gases from the valve cover are directly discharged to the carburetor through the upper branch pipe. There is also a lower branch pipe. It is designed to divert the KG bypassing the carburetor directly into the intake path.

Crankcase gas valve: from history

We examined the basic scheme of the forced ventilation system. As already noted above, the design is based on a special valve responsible for the recirculation of gases. This is a simple device that helps to reduce the level of harmful substances. For the first time the need for these devices began talking in the 70's. It was during this period that we began to seriously think about the environment and about the harmful effects that exhaust gases exert on it . By using the recirculation valve, the crankcase gases are burned in the cylinders. So burn various harmful impurities, oil and other substances. The valve of crankcase gases changed significantly several times over 15 years. Engineers changed its device and operating principle. In the 77th year, a mechanical design with positive back pressure was developed and applied. After 2 years, in the 79th year, it was replaced by the same mechanical valve, but with negative back pressure. In 1988, the introduction of discrete valves with three solenoids began. Since the 1990s, discrete devices with two solenoids have been actively used. This mechanism can control the flow of gases through one large and one small hole. Three different flows are provided. This design proved to be the most reliable and successfully used even now on modern cars (for example, the crankcase gas valve "Kia Sorento").

Operating principle

When a mixture of fuel and air burns in the chamber at very high temperatures, nitrogen is released. Together with oxygen, it can form dangerous substances that have a destructive effect on the environment. These are nitrogen oxides. With a certain condition in the combustion chamber of the engine, the combustion temperature is higher than the standard one, which is why the amount of nitrogen oxide emissions significantly increases. Most of them try to break into the bottom of the engine block. In order that the pressure does not grow to a critical level, it must be vented. Until the recirculation system was introduced on the engines, the gases, as already noted, were discharged through the breather in the engine crankcase. Let's look at how the crankcase gas valve works. The principle of operation is very simple. It is based on the effect of vacuum in the intake manifold. Due to this, by means of a vacuum converter, the valve shaft moves, thereby opening the device. In modern cars, two types of devices are used. These are mechanical and electronic systems. In turn, electronic divide into two more types - discrete and linear. In the vacuum diaphragm case on the cylinder block there is a vacuum branch pipe. He joins the carburetor or throttle corner. Depending on what kind of discharge occurs in the intake manifold, the diaphragm blind opens the infinitely variable shift lever during opening. As a result, a special signal is generated to open the diaphragm of the electronic valve. When the signal level rises, the diaphragm begins to move upward, overcoming the force of the spring and moving the plunger. This results in a hole in the valve. Gases can get into the intake manifold. If the engine is running at idle, or when the level of discharge in the manifold is small, the plunger closes. Gases in the collector will not arrive.

Valve device VKG

In modern internal combustion engines, a PCV membrane valve is most often used. Its device is extremely simple. The element consists of a body with two fittings. One serves for feeding, the second - for the removal of gases. There is also a cover, diaphragm or diaphragm and a return spring.

Features of the PCV valve

This construction works as follows. When the engine is not running, under the force of the spring, the crankcase gas valve "Audi A4" will be shut off due to the membrane. When the engine is running at idle, then due to the discharge, the membrane begins to gradually overcome the spring. Part of the gases from the engine goes to the intake manifold. At high speeds, the membrane is completely open. Gases are fully absorbed into the collector.

Typical malfunctions

All the problems that can arise with this device can be divided into two types - these are different valve failures and clogging. We'll talk about them below. Very often, among the reasons why the crankcase gases fail (the "Polo 1.4" is no exception), the natural wear of the components and parts in the cylinder-piston group is highlighted. If there is a weak compression in the combustion chambers, and the oil ring on the piston does not retain lubricant, then the pressure of the gases in the crankcase increases. The ventilation system can not cope with this phenomenon. Oil, soot and other products of combustion literally clog pipes and hoses, thereby violating the integrity of the valve membrane. In the event that the nozzles of the ventilation system are clogged and clogged, the gases will try to exit through any possible places and connections. Therefore, the gaskets flow and oil is squeezed out through the oil seals.

About the clogs

The crankcase gas valve "Passat B3", like all the others of this type, is susceptible to clogging. This may cause the machine to jam. The phenomenon will necessarily affect the characteristics of the engine. If the valve is jammed in the open position, idling speed rises, fuel consumption may increase to a considerable extent. The engine idling will become unstable. If the crankcase gas valve (Skoda Octavia often suffers this) jams in the closed position, then there will be an increase in the pressure of the gases in the crankcase. There are oil leaks from all kinds of seals and seals. Often with such malfunctions, the operation of the lubrication system is severely impaired .

How to check the device? Method number 1

If the car has these symptoms, you need to check the operation of the PCV valve. There are two ways to test. If you remove the crankcase gas valve "Passat B3", then its blowdown must pass only one way. In the reverse air should not practically pass. Allowed only a small amount of it, which can pass. If this is the case, then the system is OK.

Method number 2

The second option is testing on a running engine. To do this, disconnect the valves from the side of the intake manifold from the valve. If the element is working, then it will be empty. This can be felt by attaching a finger to the nipple. You will feel, as the finger is sucked to the hole. If the crankcase valve "Tuareg Volkswagen" is faulty, then there will be no discharge in this place.

Features of the crankcase ventilation system for VAG vehicles

The crankcase ventilation on VAG vehicles has a relatively complex device. The system uses a huge number of parts from plastic and rubber nipples. During the active use of the car, the hoses are coked. Then you have to clear all the elements. Previously, in this case, the problem was solved simply. Bypassing the ventilation system, a branch pipe or hose was installed on the lid of the valve system and gases released into the environment. But this method has a lot of drawbacks. Gases seriously pollute the environment, the driver and passengers in the car also breathe them. On modern cars, no one else does this, and if the VW crankcase valve is clogged, the owner must clean the entire system. Crankcase gases on VAG group engines are not output from the valve cover, but from the engine block in the hole of which the oil separator is installed (located on the right side of the unit). The device does not allow the oil to rise on the nozzles in the CWC. There are exactly gases and nothing more. A plastic tube is attached to the oil separator, and a tee is installed between the hose and this tube, in which the valve is located. It can work in three modes. At idle and high revs, it is closed, and opens when the engine is running at medium revs.

Conclusion

As can be seen, the efficiency of the engine depends on one small element. When the car is actively used, it is necessary to monitor the condition of the valve and the entire ventilation system, and, if necessary, clean up.