Rear axle breather device

An engine breather (breathing valve) is a device for equalizing the pressure in a closed container relative to atmospheric pressure. In other words, the breather valve allows the closed container to communicate with the atmosphere. In internal combustion engines, the breather equalizes the pressure inside the engine crankcase.

During the operation of the vehicle and the operation of the power unit, the pressure in the crankcase may increase, as a result of which crankcase gases escape through the breather, excess engine oil is squeezed out, etc. If the pressure in the engine crankcase is below atmospheric pressure, then outside air enters the crankcase through the breather, thereby eliminating the difference between external atmospheric and internal pressure in the crankcase cavity.

We also recommend reading the article about what EGR is. From this article you will learn about the design, purpose and operating principles of the exhaust gas recirculation system.

Where is the breather installed?

Breathers on a car are installed:

in the engine itself; V.

What is a breather for?

The engine breather is part of the main unit in any car. A narrow-profile part that plays an important role during the operation of the main unit of the vehicle. The device looks like an auto valve. Breathers are installed to reduce pressure in the crankcase itself.

The device reduces pressure when gaseous substances are released from the engine housing, and it helps to quickly reduce pressure. In the automotive world you can find different cars. In some models and brands, breathers are installed not only in the engine, but also in the gearbox, for transfer cases, gearboxes and the rear axle of the car.

The principle of operation of the breather in the engine

Today, a breather valve to reduce pressure is very often installed on SUVs. This is due to the fact that the device is suitable for off-road driving. Breathers prevent oil leakage. The heated oil in the engine promotes expansion as a result.

A breather (or breathing valve) is a device by which a container communicates with the atmosphere to maintain equal pressure. In “simple” language, the breather releases air and gases that arise as a result of the operation of the car’s devices, which makes it possible for air to pass inside when the operation of the car’s mechanisms has stopped. This is necessary in order to restore equal pressure in two planes.

Where are breathers used?

In automotive practice, breathers can be found in the engine, gearbox, front axle, and rear axle. But at the same time, it performs the same functions anywhere.

Engine breather

The engine breather releases the gases and air passing through it that are created by the operation of the cylinders, thereby preventing oil from leaking from the crankcase.

If the engine stops working, the pressure in the crankcase space and the atmosphere is equalized by the intake of air from.

This can save you from more expensive repairs. In fact, the breather, although it seems like an insignificant detail, in practice is of great importance for the health of the power unit.

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.

On the upper plane of the head, the valve drive parts are fixed, which are closed with a lid with a cap 5. A breather 3 is mounted on the cap. It communicates the crankcase cavity with the atmosphere. The breather is necessary to prevent oil from being squeezed out through the crankcase seals by gases penetrating from the cylinders. Air and gases that have escaped from the cylinders into the crankcase come out through the breather. If, after stopping the engine, the pressure of the cooled air in it becomes below atmospheric pressure, the air enters the crankcase from the outside through the breather. Wire packing soaked in oil cleans the air of dust. In some engines, the breather is located on the side wall of the block (from the side of the rod chamber) or in the neck cover for pouring oil into the crankcase. Most car engines have forced crankcase ventilation.

A sump is attached to the lower plane of the crankcase, which serves as an oil reservoir and covers the lower part of the engine. At the connector site, the pan is sealed with a cork or paronite gasket.

The principle of operation of the breather in the engine

Today, a breather valve to reduce pressure is very often installed on SUVs. This is due to the fact that the device is suitable for off-road driving. Breathers prevent oil leakage. Heated engine oil expands, causing engine pressure to increase.

The pressure in engines or in other automotive devices must find a way out. This causes oil to leak out through various gaskets and gaps. To prevent oil leakage, breathers are installed.

“Quiet, the operation is underway!” or Replacing the rear axle gearbox seal on a VAZ 2107

The sequence of work when replacing the gearbox seal is as follows:

We measure and record the moment of resistance to rotation of the flange (the axle shafts must be removed!) .
Unscrew the flange nut.
Remove the flange from the shaft splines.
Using expansion pliers, remove the oil seal. If you don't have pliers, you can pry it off with a screwdriver. Be careful not to damage the surface of the socket.
We inspect the flange. If its surface has a pronounced groove in the place where the working edge of the oil seal rubbed, then before installing the new oil seal, insert a washer 1 mm thick into the socket. If the flange is damaged on the working surface, replace it with a new one.
Lubricate the outer surface of the oil seal with lithol and carefully drive it into the crankcase socket using a mandrel of suitable diameter. If there is no mandrel, press in the oil seal by evenly tapping the end along the circumference of the outer diameter. Make sure that there are no distortions - the working edge should be strictly perpendicular to the shaft axis.
We inspect the lead-in chamfer on the flange. It should not have defects that could damage the working edge. We install the flange, avoiding sudden movements and impacts, so as not to knock the spring off the oil seal. Before installation, you can lubricate the flange chamfer with transmission oil to make the process easier.
We tighten the nut, periodically checking the moment of resistance to rotation of the flange. Remember that at the end of the tightening, the resistance in the bearings increases much more intensely than at the beginning . The moment of resistance to rotation should be 1–2 kgf.cm greater than what we recorded before unscrewing the nut. In any case, if the moment exceeded 9 kgf.cm, and the bearings in the bridge were still old, remove the flange again, take out the inner ring of the bearing and change the spacer sleeve. If the bearings are new (new means they have not traveled a single kilometer, because after a hundred kilometers they can be considered old for adjustment purposes), then the normal moment of resistance to rotation after tightening the nut for them should be in the range of 16–20 kgf. cm. Replacing the rear bearing will affect gear alignment, so please refer to the appropriate manual for this procedure .

To prevent self-loosening, the flange nut has a special plastic insert, which, when crushed against the thread, creates additional resistance both when screwing and unscrewing. As a rule, such nuts can withstand up to ten unscrewings without losing their locking properties. If in doubt, get a new nut.

We reinstall the axle shafts and brake drums, screw on the driveshaft, and fill in the oil. We make a test drive and if everything is in order, we enjoy life, until we suddenly find a treacherous spot under the bridge again...

Breather in gearbox

The gearbox must convert the torque in the engine and also change the traction force. It often happens that the gearbox starts to work poorly due to the fact that the gearbox breather is clogged. To avoid any damage, you should clean not only the breather in the engine, but also all the others that are installed in different parts of the machine.

In the gearbox, the breather is located on the gearbox housing cover. Sand or dirt getting into the breather will cause the wheel mounted on the secondary shaft to jam. As a result, wear of bearings and synchronizers increases. It is necessary to wash the breather during each technical inspection, or even more often. If the valve is clogged, the pressure in the gearbox will increase, which will lead to oil leakage through the seals.

About the consequences of untimely “treatment”

And just as a runny nose can lead to serious problems in the body, even some kind of meningitis, oil leaking from the bridge can lead to serious “diseases” of the drive axle: overheating and jamming of bearings, scuffing on the surface of the gear teeth of the main pair, their rapid wear, increased noise and other troubles, including jamming of the main gear itself. Therefore, if you discover severe oiling in the area of the drive flange, or, even worse, an oil stain on the ground under the gearbox, you should not delay the “operation”. However, if “well, I can’t go on sick leave right now,” then by regularly monitoring and replenishing the oil level in the gearbox, the car can be operated for some time without any special consequences for the health of the bridge.

Bridge breathers

There is oil inside each axle that connects the wheels. The internal cavity must contact the external environment, and it does this through the breather. With the help of this valve, an increase in pressure inside the bridge itself is eliminated.

Oil pressure rises when it heats up during forward gear operation. The breather also performs a protective function. It protects the bridge from water entering it when the car overcomes a water barrier. There is also a special hole in the middle of the bridge through which oil drains.

Particular attention should be paid to the rear axle crankcase breather. It is located on the rear axle boat, on the right side, in the upper part. As a result of this valve being clogged, oil may leak. To get rid of this problem, you need to clean the breathers from dirt. You also need to check the free movement of the breather cap. It should move in all directions.

After cleaning the breather, you should check it again after a short run of 20 km. If traces of oil are detected again, this will indicate a malfunction of the device that needs to be replaced. The rear axle breather must always be in good condition, because it plays an important role in the operation of the entire vehicle.

The vast majority of motorists, even those who have been driving for decades, will find it difficult and will not be able to answer if you ask them what an engine breather is, where it is located and what it is needed for. This is not surprising, because this small part does not fail very often and many do not even know about it.

A little anatomy

In the last years of its life on the AvtoVAZ assembly line, the classic Zhiguli remained perhaps the only passenger car in the world with a rigid drive axle. This design is simple and technologically advanced in production, but has serious disadvantages in operation:

large unsprung mass of the bridge, which negatively affects the smoothness of the vehicle;
tendency to steer when one of the wheels hits an obstacle - at this time, due to the misalignment of the bridge, both wheels tilt from the vertical and tend to roll in the direction of the tilt;
reduction in the useful volume of the trunk, because there must be free space between the axle and the car body for the axle to move during the compression of the suspension.

The advantage of a rigid axle, in addition to manufacturability, is its better adaptability to bad roads: the ground clearance under the axle practically does not change depending on the load, and the wheel drive is reliably protected from external influences by the axle housing.

The Zhiguli bridge consists of a stamped-welded bridge beam (such beams are called “Banjo” for their characteristic shape), a main gearbox with a differential, and axle shafts. The gearbox is made in a separate open housing, the flange of which is bolted to the crankcase. A drive gear with a driveshaft mounting flange and a differential with a driven wheel are mounted in the housing on bevel bearings. The main gears are hypoid, that is, their axes are located at an angle of 90 degrees to each other, but do not intersect (they are crossed). The amount by which the axis of the drive gear is offset relative to the axis of the driven gear is called hypoid offset. Such a transmission, if it is precisely manufactured and well adjusted, operates smoothly and with the least noise, but due to the intense sliding of the curved teeth, it is very sensitive to the quality and quantity of oil in the bridge.

The design of the bridge is relatively simple and technologically advanced, although it is not without its drawbacks

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.

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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.

How to replace the rear axle gearbox seal of a VAZ 2107 with your own hands: step-by-step instructions.

Secure the driveshaft using a screwdriver/spade identical to the photo and remove the 4 bolts securing the driveshaft.

Carefully hang the disconnected shaft, for example, on a rope to the muffler.
Determine the moment of resistance to turning the drive gear (it will help you avoid making mistakes during assembly), this can be done in different ways.

Method No. 1 - the most accurate - involves using a torque wrench or a dynamometer and a rope.

If using the latter tools, wind the rope around the flange a couple of turns, as shown in the photo, and attach a dynamometer to its free end. Then start winding the rope, gradually pulling back the device. As soon as the flange begins to rotate with the rope, pay attention to the readings of the device and write them down. After replacing the oil seal and installing everything in its place, this figure should remain unchanged.

If you have chosen a torque wrench as an assistant, make sure that its measurement range (scale) is at least 147 Ncm (15 kgfcm), and start tightening the flange mounting nut with it. The force that you need to move it from its place is the required moment of resistance.

Method No. 2 is useful for those who do not have any measuring equipment at hand, but have a colored marker. All you need to do is make 2 marks with it: the first on the nut, the second on the flange itself - as shown in the photo.

Pay attention to the mark on the nut - it should be made exactly on top, and not on the edges, otherwise it may simply be erased when unscrewing.

Using a wrench and a socket, unscrew the central fastening nut of the gearbox flange, but first you will have to lock the flange itself. The most convenient way to do this is with a homemade wrench made from a piece of pipe and two bolts (see photo).

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.

Necessary tool

To clean the breather on a VAZ engine, check and replace the hoses, you don’t need any special skills or specialized equipment; a standard kit is enough. To complete the work you will need:

set of keys No. 7-13;
flat and Phillips screwdrivers;
washing liquid, kerosene will do;
container where washing will take place;
rags;
breather gasket;
heat-resistant silicone-based sealant;
if necessary, a set of new hoses will be required - separately for the carburetor and injector.

This tool can be found in any garage, so there are no problems with its selection. It is better to take rags that do not separate into individual elements, since during washing they can get into the engine.

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.

Useful tips

As a general rule, you should check all existing breathers on a particular vehicle (engine breather, transmission breather, axle breather, etc.). The fact is that oil particles can be squeezed out through the breather during its operation, which leads to active contamination.

In practice, breathers need to be dismantled and cleaned of dirt and oil residues. If cleaning does not produce results (in the case when oil “presses” out of the gearbox, motor or axle precisely because of a faulty breather), the device must be completely changed.

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Also, before cleaning, you need to know how to remove the breather. On many cars, it is enough to remove the rubber cap on top and then clean the valve. Some other models may not have a rubber breather cap, and the breather is located in the 5th gear cover. In this case, cleaning is also carried out using improvised means.

Let us also add that before removing the breather for cleaning or replacing it, you should thoroughly clean the seat from dirt (so that the device does not become dirty again or the new breather does not fail after a short period of time).

Please note that when checking both old devices and new breathers, you must separately make sure that the breather cover moves freely in all directions. At the same time, we would like to add that the rear axle crankcase breather deserves special attention (on many cars it is installed in the upper part of the rear axle crankcase, closer to the right side)

This valve is subject to active contamination. If the breather becomes dirty or stops working for other reasons, oil leaks from the bridge due to increased pressure

At the same time, we would like to add that the rear axle crankcase breather deserves special attention (on many cars it is installed in the upper part of the rear axle crankcase, closer to the right side). This valve is subject to active contamination. If the breather becomes dirty or stops working for other reasons, oil leaks from the axle due to increased pressure.

In this case, you should start with cleaning. After cleaning, it is recommended to drive 20-30 km. If the leak continues, and there are no other obvious reasons, the rear axle breather needs to be replaced. If oil drips still appear, you should look for a fault not related to the breather.