Engine breather: what is it, where is it located and how does it work?

Not all motorists, especially beginners, know what an engine breather is for and what it is. This element is often mentioned in vehicle operating recommendations. This element helps diagnose important problems that are directly related to the car’s engine. Why? Yes, because often problems with this element can subsequently lead to problems with the power unit. And as a result, all this will result in expensive repairs. For this reason, every motorist should know everything about such a device and have at least the slightest idea of how malfunctions in its operation can be prevented.

What is an engine breather and why is it needed?

Everyone knows that the internal combustion engine, the same one that is installed under the hood of your car, does not run on gasoline, diesel or gas, but on their mixture with air. Moreover, it is air, which costs nothing (unlike fuel, for which we regularly pay a tidy sum at the gas station), that is required many times more. But in addition to the influx of clean air and the removal of exhaust gases through the exhaust pipe, parasitic gases are formed during the operation of the internal combustion engine.

A breather is nothing more than a breathing valve that constantly relieves excess pressure that forms inside the engine during operation. The need for this simple, relatively inexpensive part is difficult to overestimate.

Why do you need to clean the valve?

The external conditions created during the operation of the breather valve often lead to the accumulation of dust and dirt in it, which interfere with its normal functioning. Because of this, excess or, conversely, insufficient pressure occurs, leading to oil leakage.

If situations arise when oil is thrown through the unit, first of all you should check whether it is clogged. To prevent oil from being thrown out, you need to remove the valve for cleaning or replacement.

The breather should be replaced with a new one in cases where it is too contaminated, and before installing a new unit, it is recommended to thoroughly clean the place where it is installed, which will avoid rapid contamination again. Breathers of other important components of the car also need to be cleaned in a timely manner to prevent car malfunctions.

Where is the engine breather located?

From engine to engine, different car manufacturers may place the breather in different places. But in most cases it is located on the valve cover, next to the filler neck. Although there may be options: it is better to clarify in the description instructions for the car or find out on thematic forums.

In the picture on the right is the crankcase ventilation system of the VAZ 2111 engine, which includes a breather:

Crankcase.
Breather.
Hose from the breather to the valve cover pipe.
Oil separator under the valve cover.
A thin hose from the valve cover to the fitting with the throttle body nozzle.
Fitting with jet on the throttle valve block.
Thick hose from the valve cover to the intake pipe..

But the breather is installed not only in internal combustion engines. It is in:

Gearbox. Otherwise, the gearbox would begin to operate jerkily, and the wear of the gears on the secondary shaft would increase many times over. Something similar is observed when the breather becomes clogged and ceases to perform its function.
If the design of the car provides for a separate transfer case, then a similar mechanism may be in it.
Front, and in rear-/all-wheel drive vehicles - in the rear axle. Moreover, this inconspicuous detail not only equalizes pressure, it protects the mechanisms from dirt and moisture when overcoming water obstacles.

However, even their appearance is often similar, and often identical: they perform the same function.

Crankcase VENTILATION SYSTEM

The power plant of any car is a very complex device, including mechanisms and systems that interact with each other. At the same time, the engine is not a closed hermetically sealed circuit and it also has ventilation. Crankcase ventilation is a scheme that ensures the removal of gases from internal cavities. The fact is that during combustion of the working mixture in the cylinders, exhaust gases are formed, which are under pressure, due to which part of them penetrates into the sub-piston space - the crankcase, where it mixes with oil mist and moisture formed as a result of condensation. This whole mixture is called crankcase gases. If the engine were sealed, with an increase in the amount of gases in the crankcase, the pressure inside it also increased. Because of this, a breakthrough of gases along with oil through the breather, oil seals, seals or the hole in the oil dipstick is possible. Based on this, it follows that the main task of the ventilation system is to maintain pressure inside the engine and prevent it from exceeding the permissible norm by removing crankcase gases.

Breather device

Typically, the internal structure of the breather is very simple. Let's look at it using the example of a breather for a gearbox/axle.

External breather housing. It is made of metal, so it cannot be damaged while driving.
Pressure spring. Thanks to it, the mechanism does not need an electrical/mechanical drive, everything is autonomous.
Rubber gasket. It is this that ensures tightness when excess pressure is not released.
Lock nut. The simplest method of fixation: although in other models there are a variety of options.
The breather body itself. The through hole allows the unit to “breathe”, relieving excess pressure.

Although this breather is not used for engines, the principle is the same. An elementary module that you simply cannot do without.

VENTILATION DESIGN FEATURES, OPERATING PRINCIPLE

The simplest diagram of the crankcase ventilation system used on internal combustion engines previously consisted of only one fitting - a breather installed in the crankcase. This breather connected the internal cavity of the cylinder block with the external environment, and crankcase gases simply escaped through it into the atmosphere. But this scheme had one significant drawback - the exhaust gases contained oil particles, which also entered the external environment. And this is not only loss of lubricant and the need for periodic refilling, but also air pollution. On modern cars the ventilation system is closed. It also has a breather, but a pipe is connected to it, allowing gases to be vented into the intake manifold or air filter housing, from where they enter the cylinders and burn. That is, the atmosphere is not polluted by them. Additionally, the system includes elements that ensure oil separation and return back to the crankcase so that it does not enter the cylinders along with the gases.

There are several options for oil separators, and on cars from different manufacturers they may differ in design and operating principle. It is worth noting that part of the exhaust gases enters the supra-valve space, and they must also be removed. Therefore, the entire circuit of the engine ventilation system on a modern car consists of a breather, an oil separator and two pipes. Additionally, a special valve can be included in the system to regulate the pressure of gases entering the intake manifold. The configuration of the system can be very different, but this does not change its purpose and operating principle. For example, consider the ventilation design of the VAZ-2110. At the bottom of the cylinder block of this car there is a breather, onto which a pipe is attached; the second end of this hose is connected through a fitting to the cylinder head cover. At the same time, an oil separator is located inside this cover at the inlet of the pipe. On its other side there is another fitting, to which a tube is connected that goes to the air inlet pipe.

The principle of operation of such ventilation is simple - gases enter the cylinder head cover space through the breather and pass through the oil separator, while the separated oil flows to the valve assembly. After this, the gases are mixed with those that have broken into the supra-valve space and are supplied to the air pipe, and then to the manifold. There is no pressure regulating valve in this car. On other machines, the oil separator may be located immediately next to the breather, and a valve is installed behind it.

Why is there smoke coming from the breather?

There can be only one malfunction of the breather: it began to poorly pass accumulated gases, comparing the pressure inside the engine with atmospheric pressure. But the smoke coming from it can say a lot:

The cylinder oil scraper rings were stuck or worn out. Simple decarbonization using traditional methods or special chemicals will not help here, so you will have to disassemble the engine.
Likewise, if one/several exhaust valves burn out. A simple compression test will help determine this.
Oil seals. Just replace them when it's time or they show signs of increased wear.
The shaft seals, which allowed oil vapors to pass through, were worn out. Change them without hesitation, preferably without shelving them.
The oil in the engine is old and needs replacing for a long time. No comments: as practice shows, repairing the “heart” of a car is tens of times more expensive than replacing it.
White smoke on a hot engine - coolant enters the lubrication system. You'll have to look for where exactly the leak is.
Oil overflow. In an internal combustion engine, it is just as dangerous as underfilling: engine wear/fuel consumption increases significantly, so check its level with a dipstick on a level surface when the engine is well warmed up. Then you will see how well the technicians at the service station (or you yourself) performed its replacement/topping up.
The oil is of poor quality/not suitable for the car/counterfeit. There is only one way out - replace it. Likewise, if you filled up with fuel at an unknown gas station: just don’t do it again.
Finally, the breather itself clogged from time to time, not working at 100%. Simple cleaning and preventive maintenance will eliminate this.

An impressive list of different situations. And there is no doubt that if your car’s breather is smoking, you have definitely found your case among them.

Purpose

What is an engine breather? Before answering this question, it is important to understand what it is intended for. This is directly related to the principle of its operation. The main task of this device is to reduce the pressure in the engine crankcase. When the power unit operates, various gases collect in the crankcase. Gradually they accumulate and create quite a lot of pressure. If you do not bleed them, the engine may stop, the pressure will back up the pistons.

In this case, the gas will seek an exit through any available hole. To prevent this from happening, a breather is installed. This device is also used to ventilate the crankcase. Unnecessary gases are removed from it. Thus, the temperature inside the engine is slightly reduced. The engine breather has two tasks: ventilation and releasing excess pressure. In some cases, the operation of the breather can indicate the presence of problems in the engine. If the rings are stuck or the piston is damaged, gray smoke characteristic of the exhaust will fly out of the hose. This way you can diagnose these faults without disassembling the engine. In normal condition, a slightly noticeable transparent smoke comes out of the breather.

Malfunctions

The most common cause of problems with the breather is that it is clogged. This is manifested by squeezing oil through any available holes. The most common problem is the crankshaft seals. This is where the oil usually passes through. It is much less common for grease to be forced through the spark plugs or under the valve cover. The dipstick can also often be knocked out. When the pressure increases, it “shoots off” with a characteristic pop. The impact may be so severe that it leaves a mark on the hood. If any of these signs appear, you need to clean the breather valve.

DIAGNOSING THE CAUSE OF OIL RUSSIAN

Since there are a large number of reasons for oil leaking through the breather, a comprehensive check of the engine is necessary to determine exactly why the problem arose. At the same time, to carry it out, you don’t even need to disassemble the power plant, it’s just enough to take measurements of some parameters, as well as visually assess the condition of the ventilation. For example, let's take the already mentioned VAZ-2110. Let's assume that in the engine of this car, plaque and oil deposits were noticed in the intake manifold, which indicates oil leakage through the breather.

To determine what caused this problem, you will need little - a set of open-end wrenches, a screwdriver, a compression gauge. We'll start the test by assessing the exhaust gases. To do this, just start the engine and look at their color shade. If it is gray or black in color, this indicates oil getting into the cylinders due to wear or sticking of the CPG rings or problems with the timing belt. Only this can help determine the cause; read more here - the causes of smoke from the exhaust pipe. It is also necessary to check the compression in all cylinders. In the normal state of the cylinder-piston group, it should be in the range of 11-13 MPa. The difference between the readings in the cylinders is allowed to be no more than 1 MPa.

If the compression in one cylinder is significantly lower, it can cause oil leakage. But why exactly this is happening - rings or valves - can be determined by the spark plug that was installed on this cylinder. Heavy carbon deposits on it will indicate a problem with the CPG.

But if the compression is low, and the spark plug has a normal working appearance without carbon deposits, you should check the valves. If the compression in all cylinders is normal, we proceed to inspect the elements of the ventilation system.

Service

To eliminate the possibility of the seals being pressed through, you need to periodically clean the engine ventilation system. If you remove dirt twice a year, there will be no problems with the work, since the dirt is removed with a rag.

Dirty breather of Skoda Octavia

You should start with the breather itself. In some engines it is secured with bolts, while in others the breather is tightly seated in the seat.

After removing the breather wall, carefully wipe it with a rag. If the contamination is strong, then they are removed with wire or a screwdriver. Before installing the breather, wipe the seat.

We wash and clean the ventilation system pipes with a cleaning rod made of rags and wire.

The oil trap screen installed in the valve cover also needs to be cleaned. If it is slightly dirty, just wiping is enough.

If the mesh is heavily contaminated with deposits, then everything will have to be removed using a knife, screwdriver, or wire. You can also simply burn out the deposits. To do this, pour a little gasoline onto the grid and set it on fire.

Such simple actions allow you to keep the crankcase ventilation system, which includes the breather, in working order and prevent the seals from being pressed or oil being squeezed out through the dipstick.