Why Does Oil Squeeze Through A Breather? How To Troubleshoot?

A relatively common problem in many cars of domestic and foreign production is driving oil through the breather. In winter, especially with the onset of a significant cold snap, a malfunction can be encountered when the breather has frozen, has squeezed out the oil and there are visible leaks on the outer surface of the power unit. Immediately, we note that this symptom, as well as smoke and oil from the breather, are the reason for the immediate diagnosis of the engine, since ignoring the indicated problem can lead to a quick and costly repair of the engine.
Note that if the oil goes through the breather, the diagnosis of the root cause may be difficult. Skills, special equipment, etc. will be required to determine the exact problem. However, in some cases, the driver can understand why oil is running from the breather without the involvement of third-party specialists. In other words, diagnostics is carried out independently in the garage. In this article, we will talk about why the oil drips from the breather, as well as what the car owner should do if the oil throws through the breather.
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Oil from the breather: what to do and how to find the cause?

To begin with, during the operation of the engine, so-called crankcase gases accumulate in the crankcase. In order not to create excessive pressure, there is a special valve for ventilation. This solution allows the closed crankcase to communicate with the atmosphere. The lid is a breather. In simple words, the breather on the internal combustion engine is needed to equalize the pressure inside the engine.
You should note that in the crankcase, gases mix with oil mist. As a result, particles of grease fall into the breather. Although there is a special oil trap inside the unit, a certain amount of oil may come out. Considering this information, slight contamination of the system is allowed, which is the norm. In cases where there is a lot of lubrication, you should look separately for why the oil throw from the breather.
On injection engines there are visible traces of oil ingress in the throttle area, the power unit also loses its acceleration and power, and fuel consumption increases significantly. It turns out that to check it is necessary not only to inspect the outer surfaces under the hood but also to remove the air filter, throttle unit, etc.

Why oil flows through the breather?

If oil appeared from the breather, there might be several reasons. Given the various features before self-diagnosis need to pay attention to the additional symptoms.

  1. First of all, oil presses as a result of significant wear of the piston rings. It means that gases from the combustion chamber penetrate through the seal into the engine crankcase, after which it creates too high pressure. Excess pressure causes the oil to flow through the breather.
  2. Another possible cause may be clogging the drain of the oil seal. In this case, gases and oil particles, which lose the ability to pass normally, exit through the breather, and not through the purifier.
  3. Also in the list it is worth noting a significant reduction in air filter capacity. In this case, the motor does not have enough intake air. The result is the appearance of oil in the filter housing and on the filter itself.
  4. Possible problems with the breather itself should not be excluded. As a rule, a valve fails, a passage blocks in the breather, etc. Normal ventilation is disturbed, the exhaust gases enter the crankcase of the engine and raise the pressure.
  5. In some cases, the overflow of engine oil is much higher than the recommended level leads to the fact that the excess flow through the breather. It turns out, excess oil presses from the engine. In this situation, you should check the level of lubrication and bring it back to normal when problems are detected.

Drives the oil through the breather: diesel and gasoline engine.

Engine diagnostics for oil leakage through a breather involves an integrated approach. To check, there is no need to disassemble the power unit. It becomes clear that at the initial stage, it is necessary to assess the condition of the breather, make sure that it is working and clean the device if necessary. Also, check the oil level on the dipstick. If the level is all right and there are no other additional symptoms of a malfunction, then it is optimal to replace the breather with a known good.
Making sure that the breather is in good condition and the ventilation is at an acceptable level, you will need to make a series of measurements and assess the state of the CPG. As already mentioned, the cause may be broken rings, that is, you need to measure the compression in the engine.
Also on the need to measure the compression can additionally indicate the colour of the exhaust gases. To check it is enough to start the engine, and then evaluate the exhaust. If the engine smokes blue or gray smoke, then this may be a sign of engine oil getting into the cylinders due to the wear of the piston rings. During the compression test, you need to measure the readings in each cylinder. In the normal state of the CPG, the compression should be at the level of 11 MPa and above (it recommends that you read the technical literature for a specific type of internal combustion engine). In case of a run-up detection on indications in cylinders, the differences should not exceed 1 MPa.
The absence of a reduction in compression will indicate that further checks will be related to the ventilation system. The method of checking this system will consider the example of the domestic model VAZ 2110. On other cars, there may be some individual features, but the general principle will be similar.

  • At the very beginning you need to disconnect the tube from the valve cover, breather and duct pipe. Then it is necessary to assess the degree of contamination. If the tubes are clogged or dirty, then they can be cleaned with a carburetor cleaner or gasoline. After you need to blow them with compressed air or dry naturally.
  • Next, you need to get to the oil separator, unscrewing the fixing bolts and removing its cover. After that, the oil separator removes. This device is made of special plates. It is required to disassemble the element and wash it. Washing can do in gasoline, then dried.
  • In parallel, it is recommended to inspect and flush the valve, as well as check the stroke of the rod. It is possible after removing the device. Shimming of the valve is also eliminated by flushing. The entire list of actions described allows you to keep the crankcase ventilation system clean and maintain its efficiency.

Let’s sum up.

With this in mind, it becomes clear that the increase in pressure of crankcase gases and leakage of oil through the breather indicate several problems with the breather or the engine. Rapid detection and removal of faults will reduce the cost of repairing the power unit. It is relevant if the problem eliminates at an early stage, that is, without consequences that arise after prolonged ignoring the fault and further active operation of the engine.
Finally, we note that often enough abundant leakage of oil through the breather does not appear immediately. In other words, the lubricant may leak slightly, which is sometimes unobtrusive. In other cases, through the breather, about 0.5 or a litre of oil can leave the lubrication system, taking into account a small mileage (1-3 thousand km on average). With such a significant leakage, the operation of the internal combustion engine is stopped, diagnostics and repairs are carried out.