Internal combustion engine lubrication systemsimilar to the human circulatory system. Oil, like blood, circulates in a closed circle, lubricating, cooling and cleaning moving parts. All this, of course, occurs under a certain pressure, the reduction or excess of which will invariably lead to disruption of the working process.
The slightest leak of oil from the engine is a signal that a depressurization of the system has occurred. And this is a serious reason to think about the diagnosis of the power unit.
In this article we will talk about the reasons for what arises, and how to eliminate the leakage of oil from under the valve cover.
What is a valve cover
Этот элемент двигателя внутреннего сгорания designed to protect the gas distribution mechanism from the ingress of dirt, dust and moisture. In addition, the cover protects all the engine compartment from the oil that is supplied under pressure for lubricating the timing.
The first internal combustion engines did not havevalve cover, because of what the valve timing mechanism constantly had to be washed and cleaned. Over time, the timing began to cover stamped lids of thin sheet steel. Today, this element is made from aluminum by casting. And this is no longer just a lid, but an entire structure, the tasks of which include the timing protection, participation in the crankcase ventilation process, and the collection of oil sprayed by moving parts of the timing mechanism.
In order to ensure the tightness of the valvethe cover is attached to the cylinder head through a rubber or silicone gasket. In some new cars, the gasket is not installed at all: its role is performed by a layer of special sealant.
Possible leak points
If you notice that oil is flowing from under the valve cover, try to pinpoint the leak. Most often the lubricant can leak:
- in places where the cover is connected to the cylinder head due to gasket wear or excessive pressure in the system;
- in places of bolted connection of the cover with the cylinder head;
- from the oil filler neck.
In rare cases, oil leakage may occur on the body of the cover itself. This may be due to mechanical damage or factory casting.
Causes of oil leakage from under the valve cover
Oil leakage from under the valve cover may be due to two factors:
- loss of gasket its sealing properties;
- increasing oil pressure in the system.
In the first case, the strip due to significantoperation time and the effect of high temperature simply coarsens or cracks, which can not but affect the tightness of the system. This is not the worst case. It is enough to change the old gasket to a new one, and the tightness will be restored.
But if oil leaks from under the valve cover are caused by an increase in pressure inside the system, further diagnostics will be required. And you need to start with the measurement of pressure.
How to measure oil pressure
As already mentioned, the lubricant circulates aroundspecial channels inside the engine under the pressure created by the oil pump. The normal oil pressure for each engine is different, it all depends on its volume, number of cylinders, valves, etc. In order not to guess, look in the manual of your car, everything is indicated there. So, if the pressure in the system decreases, its sensor will instantly signal to you about this lamp that has ignited on the instrument panel.
What does high oil pressure mean?
Для автомобиля, как и для человека, «гипертония» does not bode well. In our case, it is evidence of problems with the lubrication system. So, if in your car oil flows from under the valve cover, and you are diagnosed with an increase in its pressure, the reason for this may be:
- violation of normal crankcase ventilation due to clogging of oil separator grids;
- clogging of the oil channels of the cylinder head;
- clogged oil filter;
- jamming of the reducing valve in the closed position.
Consider these reasons in more detail, and in the order in which it is better to diagnose: from the simplest to the complex.
Violation of the normal crankcase ventilation
Let's start with the most common reason for raisingpressure in the lubrication system, found in domestic cars. Most often, the oil from under the valve cover VAZ begins to leak because of a violation of the crankcase ventilation. Simply put, crankcase gases, which should be free to leave the engine, meet obstacles in their path, and begin to accumulate inside, creating excessive pressure. In this case, it not only pushes the oil out from under the valve cover, but can also throw it out through the breather into the air filter housing.
Что же это могут быть за препятствия?First, the oil separator mesh, if it is clogged with combustion products. And secondly, the usual deposits and dirt on the inner walls of the fittings, which are joined by ventilation hoses. So, if it drives the oil out from under the valve cover in our car, do not be lazy to remove the valve cover and rinse the oil separator net, and at the same time clean the fittings.
Clogged oil channels and filter
The cylinder head has a whole networkspecial channels through which the oil moves. The use of low-quality lubrication, ingress of dirt into the system, engine overheating are the main reasons why these channels can become clogged. When this happens, the oil pressure naturally increases, because the oil pump continues to work.
The same thing happens when the filter is clogged.It loses its capacity by creating increased pressure in the system. And there is nothing surprising in the fact that oil flows from under the valve cover, if you changed the filter a few years ago.
This problem is resolved by replacing the filter element and flushing the system with special fluids.
Pressure reducing valve malfunction
Often the increase in oil pressure isdue to a malfunction of the oil pump's pressure relief valve, because it regulates it. The most common cause of a malfunction is jamming in the closed position, caused by friction products (small chips) or dirt getting into its mechanism. Get rid of this problem is easy. The valve can be easily disassembled and cleaned, however, to do this it will be necessary to dismantle the oil pump.
Select the valve cover gasket
Pay enough attention to the choice of gasket, soHow to eliminate the leakage of oil from under the valve cover, using low-quality product, you are unlikely to succeed. Preference here is better to give the original parts, knowing its factory catalog number. If the design provides a rubber gasket, make sure that the rubber is soft and does not have any cracks or flows. All these defects will definitely affect the tightness.
Do I need to lubricate the rubber gasket sealant
Насчет использования герметика мнения auto mechanics diverge. Some consider its use unacceptable, while others, on the contrary, argue that only with it can one achieve complete impermeability. Let's just say that if the surfaces of the cover and the cylinder block have roughness, the use of sealant is desirable, but only if it is applied with a neat thin layer. If the surfaces are perfectly smooth, you can do without it, because a few years ago nobody used this kind of compactor. Well, for cars where the gasket is not provided by the design, you can not do without sealant.
If the oil flows from the neck or in the bolted areas
It happens that the oil does not flow from the junctionthe mating surfaces of the cylinder head and valve covers, as well, for example, from the oil filler neck or where there is a bolted connection. The reason for such leaks is still the same overpressure. Eliminating the causes of high pressure, it is recommended to replace the rubber bolt seals (if they are provided for by the design), and also check the tightness of the oil filler cap.
Helpful Tips
Finally, here are some useful tips that will allow you to avoid problems with oil leakage or to cope with them faster.
- Replace the engine oil and the oil filter in a timely manner.
- Use only high-quality lubricant.
- Do not allow dirt, water, and other process fluids to enter the lubrication system.
- With the passage of THAT do not forget to check the oil pressure in the lubrication system. In case of detection of its increase, immediately make auto repair.
- Do not overheat the engine.
- Check the operation of the units responsible for crankcase ventilation.
- When choosing a gasket for the valve cover, give preference to the original product.
- Apply sealant to the gasket with a thin, continuous layer. Do not allow it to fall on the elements of the gas distribution mechanism.
- Do not overtighten bolts when tightening valve cover.
- Having found leaks of oil from under the valve cover, do not over-tighten with diagnostics and repairs.
