Oil flows from under the valve cover. Oil leak - what to do
Lubrication system of internal combustion enginelike 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 a disruption in the work process.
The slightest leakage of oil from the engine - a signal to the fact that there was a depressurization of the system. And this is a serious reason to think about the diagnosis of the power unit.
In this article we will talk about what causes, and how to eliminate the leakage of oil from under the valve cover.
What is the valve cover?
This element of the internal combustion engineIt is designed to protect the gas distribution mechanism from getting into it dirt, dust and moisture. In addition, the cover protects all the engine compartment from the oil, which is supplied under pressure for lubrication of the timing.
The first internal combustion engines did not havevalve cover, because of which the timing mechanism has always had to be washed and cleaned. Over time, the timing was covered with stamped covers made of thin sheet steel. Today, this element is made of aluminum by casting. And this is not just a cover, but a whole structure, whose tasks include protection of the timing, participation in the process of crankcase ventilation, 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 via a rubber or silicone gasket. In some new cars, the gasket is not put at all: its role is performed by a layer of special sealant.
Possible leak locations
If you notice that oil flows from under the valve cover, try to pinpoint the leakage location. Most often, the grease can flow out:
- in places of connection of a cover with a head of the block of cylinders owing to deterioration of a lining or superfluous pressure in system;
- in places of bolted connection of the cover to the cylinder head;
- from the oil filler neck.
In rare cases, oil leakage may occur on the lid body itself. This can be the result of mechanical damage or factory rejection during casting.
Causes of oil leakage from under the valve cover
The leakage of oil from under the valve cover can be due to two factors:
- loss of their sealing properties;
- increase of oil pressure in the system.
In the first case, the gasket is due to a significantthe operating time and the influence of high temperature simply coarsen or crack, which can not but affect the integrity 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 leakages from the valve cover are caused by an increase in pressure inside the system, further diagnostics will be required. And you need to start it with the pressure measurement.
How to measure the oil pressure
As already mentioned, the lubricant circulates throughSpecial channels inside the engine under the pressure created by the oil pump. Normal oil pressure for each engine is different, it all depends on its volume, the 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 immediately signal to you about this lamp on the dashboard.
About what high oil pressure says
For a car, as for a person, "hypertension"does not bode well. In our case, it is evidence of a malfunction in the lubrication system. So, if in your car oil flows from under the valve cover, and you diagnosed increasing its pressure, the reason for this may be:
- violation of normal crankcase ventilation due to clogging of the oil separator grids;
- clogging of oil channels of a head of the block of cylinders;
- clogged oil filter;
- jamming of the pressure relief valve in the closed position.
Consider these reasons in more detail, and in the order in which it is better to carry out the diagnosis: from the simplest to the most complex.
Malfunction of normal crankcase ventilation
Let's start with the most common reason for the increasepressure in the lubrication system found in domestic cars. Most often, the oil from under the valve cover of the VAZ starts to ooze due to a malfunction 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 presses oil from under the valve cover, but can also be thrown out through the breather into the air filter housing.
What kind of obstacles can this be? First, the oil separator grid, if it is clogged with combustion products. And secondly, the usual deposits and dirt on the inner walls of the fittings, to which the ventilation hoses are attached. So, if driving oil 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.
Clogging of oil channels and filter
The cylinder head has an entire networkspecial channels, through which the oil moves. Application of low-quality lubricant, getting into the dirt system, overheating of the engine 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 happens when the filter clogs. He loses his bandwidth, creating an increased pressure in the system. And there is nothing surprising in that the oil flows from under the valve cover, if you changed the filter several years ago.
This problem is eliminated by replacing the filter element and flushing the system using special fluids.
Malfunction of the pressure relief valve
Often increasing the oil pressure isa consequence of the malfunction of the oil pump pressure reducer, because it regulates it. The most common cause of the malfunction is jamming in the closed position caused by the ingress of friction products (small shavings) or dirt into its mechanism. It is not difficult to get rid of this problem. The valve is easily disassembled and cleaned, however for this purpose 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 a substandard product, you are unlikely to succeed. Preference here is better to give the original spare parts, after learning its factory catalog number. If the design provides a rubber gasket, make sure that the rubber was soft and had no cracks or tensions. All these defects will necessarily affect the tightness.
Do I need to lubricate the rubber seal with sealant?
Regarding the use of sealant opinionsauto mechanics diverge. Some consider its use unacceptable, while others, on the contrary, say that only with it can you achieve full tightness. Let's just say, if the surfaces of the cover and the cylinder block have roughness, the use of a sealant is desirable, but only if it is applied with a neat thin layer. If the surfaces are perfectly even, you can do without it, because a few years ago, no one used such a sealant. Well, for cars where the gasket is not provided for in the design, it is impossible to do without sealant.
If the oil flows from the neck or in places of bolted connections
It happens that the oil does not flow from the junctioncylinder head surfaces and valve covers, and, for example, from the oil filler neck or where there is a bolted connection. The reason for these leaks is all the same excess pressure. Having eliminated the reasons for the increased pressure, it is recommended to replace the rubber seal of the bolts (if they are provided by the design), and also to check the tightness of the oil filler cap.
Helpful Tips
Finally, give some useful tips that will help you avoid problems with oil leakage or faster to deal with them.
- Timely replace the oil in the engine, as well as the oil filter.
- Use only high-quality grease.
- Do not allow grease, water, other process fluids to enter the system.
- When passing through, do not forget to check the oil pressure in the lubrication system. If it is found, immediately repair the car.
- Do not allow the engine to overheat.
- Check the operation of the units responsible for the ventilation of the crankcase.
- 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 come into contact with the gas distributor.
- While tightening the valve cover, do not over tighten the bolts.
- After detecting leakage of oil from under the valve cover, do not tighten with diagnostics and repair. </ ol </ p>
