Oil leaks from under the cover due to a leakage of the connection, pressure increase, and the wrong choice of gasket. You can fix most problems yourself. To extend the life of the element, you will need to follow the recommendations.
The valve cover prevents engine lubricant from splashing into the space under the hood, protects the timing belt from moisture and dirt. For tightness, it is attached through a special gasket. Some modern cars use a layer of sealant instead of a gasket.
Previously, the cover was made of metal alloys. This provided her with a long service life and a secure fit. Today plastic is used. Because of this, the resource of the part is reduced. The engine runs at high temperatures, especially during the summer season. This negatively affects the item.
If oil leaks, locate the problem. Grease can flow out at the joints of the cover with the cylinder head, at the bolted joints, from the oil filler neck. Sometimes the process also occurs due to a violation of the integrity of the element itself. This is often due to mechanical damage or factory defects.
The reasons for the leak include:
- pad;
- the valve cover itself;
- studs, bolts and nuts;
- high pressure in the engine lubrication system;
- oil cover.
Leaky gasket
This reason is one of the most common. Usually a rubber gasket is used. The material dries out over time, loses its elasticity. The gasket becomes easy to break. In addition, cracks appear on it. A cork gasket is more reliable. It has excellent performance characteristics, withstands temperature drops well. Many car enthusiasts complain that a large number of fakes have appeared on the market. Therefore, even a new rubber pad may not fix the problem.
Some craftsmen go for a little trick - they install two rubber gaskets at once. This makes the cushion larger, which prevents oil leakage. However, this practice is used mainly on VAZ cars.
The valve cover itself
The plastic element can be broken or broken if handled carelessly. Sometimes cracks appear on it. You can try to cover them with sealant, but usually this move did not fix the problem. The best option is to give preference to metal products. An aluminum analog will last much longer.
You can diagnose yourself. Remove the cover and place it on a flat surface. If there is even a small gap between the base and the object itself, there is a chance that the gasket will leak. Some craftsmen try to remove the mating plane, removing some of the material can only make it worse, since the cover will only become less rigid from this.
Sometimes the oil filler neck is the cause. It is through it that oil is poured during work. Because of it, a problem can also arise. There is another gasket under the lid that loses its density over time. Oil starts to ooze when the engine is running. In practice, this can be seen as black spots. Over time, dust sticks to such spots. The simplest solution is to replace the oil filler cap.
High pressure in the engine lubrication system
Before measuring the oil pressure, it is necessary to clarify which parameter is considered normal for a particular type of internal combustion engine. Information can be found in the specialized technical literature. Note the oil pressure emergency light on the dashboard. However, when the pressure rises, the light will not come on.
A liquid pressure gauge will be required. First, unscrew the oil pressure sensor, install a pressure gauge, measure the oil pressure in the engine. If the readings indicate an excess of the indicator, then leakage from under the valve cover is a natural result. High blood pressure happens for various reasons:
- Ventilation problems. Because of this, gases accumulate in the motor, overpressure is created. The oil starts to press out from under the lid. Sometimes a malfunction occurs due to a clogged oil separator mesh, blockage of the fittings.
- Contamination in the system. The formation of deposits in the channels leads to pressure disturbances. Other elements may also suffer from this. Standard flushing of the lubrication system and oil change will help to cope with the situation.
- The use of an oil with a high viscosity or its thickening at low temperatures. Engine oils should be selected not only with regard to tolerances, but also pay attention to seasonality. Keep in mind that when the engine warms up, the fluid becomes more liquid. Therefore, the most suitable type should be selected taking into account the condition of the engine.
Pressure relief valve stuck. The oil pump always has a certain capacity. This is done to prevent pressure loss due to pump wear or contamination. If the valve is incorrectly adjusted, the pressure in the oil system will increase. A common cause of the problem is a wedging pressure relief valve.
Studs, nuts and other connecting elements
Leaks are often caused by improper feed. If for some reason it becomes necessary to remove the valve cover, tighten it well when reinstalling it. It so happens that the bolts and studs come off. Often we are talking about a human factor, when, due to the applied great effort, the thread breaks off. In such cases, the connecting elements should be replaced with new ones.
Modern covers have metal bushings for each bolt. They are necessary for pressing the special gaskets lying in the wells of the attachment point. Sometimes the sleeve is grinded down a little along the length. This action allows for better pressing of the gaskets. The action in some situations allows you to stop the leak.
The bolts pressing the cover to the plane of the head can be pulled out over time, the metal can get tired. Therefore, some professionals recommend changing the bolts at each oil change.
Recommendations
High-quality elimination of a leak requires the selection of the correct gasket under the cover. It is best to purchase original products or analogs from well-known manufacturers. Before buying, be sure to study the item, check for elasticity. There should be no sagging or other defects on it. Do not buy if the material is cracked or looks dry.
If the mating surfaces do not have a smooth surface, a sealant can be used. It provides better connection and seals. Remember that the service life of such a gasket is short. If there is no defect on the surfaces, then it is better not to make additional layers.
During the installation and tightening of bolts, all recommendations of the manufacturer must be followed. The bolts are only tightened in a specific sequence with a specific torque.
Recommended:
- Replace the engine oil and filter in a timely manner.
- It is worth buying only high-quality lubricant.
- Do not allow dirt, water or other process fluids to enter the lubrication system.
- When passing a technical inspection, check the pressure in the system.
- Do not overheat the engine.
In conclusion, we note: if the problem is in the seal, then it is enough to simply replace it. When the pressure rises, the problem is more difficult to fix. Sometimes cleaning the channels helps, but most often the problem appears due to more serious malfunctions that require an integrated approach.
