Why does the oil in the engine foam?

Beginner motorists, who are watching the engine of their car, inevitably various questions arise. As practice shows, special attention should be paid to engine oil and engine lubrication system. For this reason, many are interested, why the oil in the engine foams.

How dangerous foaming oil

This is a natural question, which occurs when detecting any deviations in the operation of the power unit. so, oil performs the function of lubricating and cooling engine parts. At formation of foam homogeneity of this liquid is broken. Consequently, the following characteristics change, as viscosity, thermal conductivity and, finally, lubricating properties.

  • Viscosity affects the passage of oil through the channels. At thickening their blockage is possible, at strong rarefaction there can be insufficient pressure in lubricating system.
  • Thermal conductivity deteriorates due to that, that air bubbles appear in the oil (this is the foam). As a result, the risk of overheating increases, wedging, deformation of individual parts.
  • Lubricating properties are better, the more homogeneous the liquid. With poor lubrication, the probability of engine jamming increases, the service life of friction parts decreases.
  • If it happens in winter, then the foam or emulsion in the oil may freeze, which threatens serious trouble when starting the engine.

A little about the lubrication and cooling systems of the internal combustion engine

As always, to solve problems, arising, it is necessary to mention the mat part. In this case, it would be appropriate to understand that, where exactly in the engine there is oil, what other fluids are circulating inside the internal combustion engine and what can cause foaming of the lubricant.

so, in the idle engine almost all oil is in a crankcase. During operation, it circulates through the channels under the action of the oil pump, lubricates the camshaft and crankshaft. The first is located in the cylinder head, and the second - in the cylinder block. As you know, both of these nodes are separate from each other. A gasket is installed between the BC and the cylinder head. This is an important point, to which it is necessary to address a little later.

Coolant (water or antifreeze / antifreeze) poured into the expansion tank or radiator. The coolant enters the special channels in the engine block - the so-called cooling jacket. In all these places, the coolant is constantly, even when the engine is off. Circulation is carried out at the expense of the water pump (pumps).

Causes of oil foaming

The design and operation of lubrication and cooling systems are directly related to the most likely causes, why the oil in the engine foams.

  • Coolant entering the oil. It was logical to put this reason first, that was written above. Besides, she herself is unpleasant, as a consequence of more serious problems.

The most insignificant of them - a breakdown of a lining between a head and the block of cylinders of the engine. To eliminate the problem you will have to remove the head and replace the gasket. In more severe cases, antifreeze may leak through cracks in the cylinder block or cylinder head. Already here, perhaps, will have to change the whole case, as it is possible to weld qualitatively a crack in pig-iron or aluminum, but not always. And the durability of such repairs may be small.

We also recommend reading the article about it, why the emulsion is formed on the dipstick of the oil level. In this article you will learn about the causes of foam or emulsion in the oil system.

However, before disassembling half of the engine, worth making sure, whether the oil foams from the coolant that got into it. Firstly, you should carefully check the liquid itself: drops of oil in antifreeze will confirm the theory.

Secondly, with this problem, the characteristic white smoke will come out of the exhaust pipe. Third, after a slight warm-up of the motor, a sheet of paper is attached to the pipe. After, as it dries, antifreeze stains should remain. If these symptoms are not present, then the root cause should be sought elsewhere.

  • Incompatibility of oil inside the engine and oil, which was recently topped up. We are talking about those cases, when mixing mineral and synthetic oils. The point is, that they are carried out in different ways. Their molecules have not only different compositions, but also different sizes.

When mixing oils, their performance deteriorates. In some cases, externally it will be manifested in the precipitation, the appearance of foam. The way out is simple: complete oil change (perhaps, with engine flush before replacement).

  • Condensation forms inside the engine and mixes with the oil. Condensation occurs in the cold season, when the engine warms up badly, the car is rarely used, etc.. P.

Water, when mixed with oil, gives an emulsion. Outwardly, it will look like foam or white plaque. It appears at the end of the probe and under the filler cap. It happens, that it comes from the wrong oil. That is, it is not suitable for temperatures, in which the car is operated.

Let's summarize

The responsible motorist must check the oil level at least once a week or even more often. And if you notice the characteristic signs of that, foaming oil in the engine, then it is necessary to stop the operation of the vehicle and urgently diagnose.

We also recommend reading the article about it, why the engine oil pressure light may be idling. You will learn from this article, for what reasons the lamp lights up, as well as how to identify possible faults.

At the initial stage, you can do it yourself, as described above. It is important to determine the cause of the emulsion and foaming of the oil. Otherwise, there is every chance of getting serious problems. In some cases, overhaul of the internal combustion engine will be required.

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