Flowing oil from under the valve cover. Oil leak - what to do

The lubrication System of an internal combustion engine similar to a human circulatory system. Oil as the blood circulates in circles, lubricating, cooling and cleaning the moving parts. All this, of course, occurs under a certain pressure, reduction or excess of which will invariably lead to disruption of workflow.

The Slightest of oil leaks from the engine – a signal that the depressurization system. And this is a serious reason to think about the diagnostics of the power unit.

In this article we will talk about what are the causes and how to fix the leak of oil from under valve cover.

What is a cover valves

This element is of the internal combustion engine is designed to protect the camshaft from the ingress of dirt, dust and moisture. In addition, the cover protects all under-hood surface from oil, which is supplied under pressure to lubricate the timing.

The First internal combustion engines did not have valve cover, which engine timing had to wash and clean. Over time, timing cover stamped steel covers from thin sheet steel. Today this item is made from aluminum by casting. And this is not just a cover, and a design that includes the protection of the timing, and participation in the process of crankcase ventilation, and collect the oil, spray the moving parts of the timing mechanism.

In order to ensure tightness of the valve cover is mounted to the cylinder head through a rubber or silicone gasket. In some new cars the gasket is not put at all: it is the role of coat of sealer.

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Potential leaks

If you notice that the oil flowing from under the valve cover, try to pinpoint the location of the leak. Most often, the grease may leak out:

• In the joints of the cover with the cylinder head due to wear of the pads or excessive pressure in the system;
• In the field bolted connection of the cover with the cylinder head;
• From the oil fill neck.

In rare cases, oil leaks can occur on the back side of the cover. This may be the result of mechanical damage or factory defect in the casting.

The Causes of an oil leak from under the valve cover

The Leak of oil from under the valve cover can be due to two factors:

• Loss of gasket sealing of their properties;
• Increase oil pressure in the system.

In the first case the gasket due to the significant time of operation and influence of high temperature is simply coarse or crack, which can not affect the tightness of the system. It's not the worst case. It is enough to change the old gasket to the new, and integrity will be restored.

But if drips of oil from under the valve cover caused by increased pressure within the system will require further diagnostics. And must begin with measuring the pressure.

How to measure oil pressure

As already mentioned, the lubricant circulates through special channels inside the motor under the pressure generated by the oil pump. Normal oil pressure for each engine is different, all depend on its size, number of cylinders, valves, etc. not to guess, check the manual for your car, there are all marked. So, if the system pressure is reduced, its sensor will immediately signal you about it burning on the dash lamp. If it is a promotion, he did not respond. In other words, high pressure can be determine only by connecting to the engine special liquid pressure gauge sensor instead. Focusing on his testimony, we can conclude that the oil flowing from under the valve cover due to an increase in pressure in the system or in the gasket (seals).

Talking About high oil pressure

For the car, as for the man, "hypertension" does not Bode well. In our case, it is a Testament to the malfunction of the lubrication system. So, if your car is leaking oil from under the valve cover and you are diagnosed with increasing pressure, the reason for this may be:

• Disruption of the normal crankcase ventilation due to clogging of meshes of the separator;
• Clogged oil passages of the cylinder head;
• Blockage of the oil filter;
• Pressure reducing valve jamming in the closed position.

Consider these reasons in more detail and in the order in which it is better to diagnose: from the simple to the complex.

Violation of the normal crankcase ventilation

Let's Start with the most common cause of pressure increase in the lubrication system found in domestic cars. Most often, the oil from under the valve cover VAZ starts to ooze because of violations of the crankcase ventilation. Simply put, the blow-by gases are free to exit the engine, encounters obstacles, and begin to accumulate inside, creating excess pressure. In this case, it not only presses the oil from under the valve cover, but can also throw it through the breather into the air filter housing.

As it can be for obstacles? First, mesh separator, if it's clogged with the combustion products. And secondly, ordinary deposits and dirt on the inner walls of the fittings, joined by hoses ventilation. So if it blows oil from under the valve cover in our car, take the time to remove the valve cover and clean the mesh oil separator, and at the same time and clean the fittings.

Clogged oil passages and filter

The cylinder Head has a network of channels through which oil moves. The use of low-quality grease, getting into the mud system, engine overheating – these are the main reasons for which these channels can become clogged. When this happens, the oil pressure naturally increases because the oil pump continues to operate.

The same thing happens when clogged filter. It loses its throughput by increasing the pressure in the system. And there is nothing surprising in the fact that the oil flowing from under the valve cover, if you changed the filter several years ago.

Eliminates this problem by replacing the filter element and flush the system with the use of special liquids.

Faulty relief valve

Often, the increase in oil pressure is the result of a faulty relief valve oil pump, because he regulates. The most common cause – stuck in the closed position, caused by contact with the products mechanism of friction (fine dust) or dirt. To get rid of such problems easily. The valve is easy to dismantle and clean, however, it is necessary to dismantle the oil pump.

Choose a valve cover gasket

Will Pay enough attention to the gasket so as to eliminate leak of oil from under the valve cover, using a defective product, you are unlikely to succeed. Preference is better to give original parts after learning the serial catalogue number. If the design provides a rubber gasket, make sure that the rubber was soft and had no cracks or sagging. All these defects will affect the seal.

Do you Need to lubricate the rubber gasket with sealant

As for the use of sealant opinions of the mechanics diverge. Some consider him an invalid, while others argue that it is possible to achieve a complete seal. Let's just say, if the cover surface and engine block have a surface roughness, the application of the sealant is desirable, but only if it is applied neat in a thin layer. If the surface is perfectly smooth, you can do without it, because a few years ago, no such seal is not particularly used. But for cars where the gasket is not in the design without sealant is not necessary.

If the oil flows from the neck or in areas of bolted connections

It Happens that oil is not flowing from the junction of the mating surfaces of the cylinder heads and valve covers, and, for example, from oil fill cap or where there is a bolted connection. The reason for such leakage is all the same overpressure. Removing the causes of high blood pressure, it is recommended to replace the rubber seals bolts (if equipped), and check the tightness of the oil filler cap.

Helpful tips

Finally give some useful tips that will allow you to avoid problems with oil leak or faster to cope with them.

1. Timely replace engine oil and oil filter.
2. Use only high-quality grease.
3. Avoid contact with the lubrication system dirt, water and other process liquids.
4. When passing do not forget to check the oil pressure in the lubrication system. In case of detection increase, immediately make repair of cars.
5. Prevent engine overheating.
6. Check the nodes responsible for the ventilation of the crankcase.
7. Choosing the gasket for the valve cover, prefer the original product.
8. Apply sealant to the gasket thin solid layer. Avoid on the elements of the timing mechanism.
9. Then screw the lid of the valve, do not overtighten the bolts.
10. Having discovered a leak of oil from under valve cover, do not delay diagnosis and repair.