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Oil in the intake manifold: causes and remedies


In a car, all components and mechanisms must work properly, so it will be a pleasure to drive a car. By early detection and elimination of minor faults, costly repairs in the future can be avoided. In addition, this approach to maintenance is the key to the safe use of the car. It often happens that oil appears in the intake manifold. Let’s see why this is happening, how to diagnose and then fix this problem.


This problem can be identified by certain signs. The oil can be directly in the intake manifold or in the throttle body. This is the easiest way to diagnose, however, it is associated with the need to disassemble the upper part of the power unit.

Oil in the intake manifold: causes and remedies

Also, blue smoke from the chimney determines the problem. Even inexperienced drivers see it. But this symptom may indicate other problems with the engine.

You can talk about a malfunction if oil consumption has increased significantly. It is worth regularly checking its level on the dipstick. When else does oil appear in the intake manifold? You can begin to suspect a malfunction if the engine thrust has noticeably decreased and the noise level during its operation has increased.

Drops of oil on the air filter are another sign. Checking for oil is very easy. Access to the air filter on most vehicles is very easy.

There are several reasons for the appearance of oil in the intake manifold. Consider the most common of them.

crankcase ventilation

The crankcase ventilation system is designed to reduce crankcase pressure. The pressure there is formed due to the ingress of exhaust gases during engine operation. To do this, the crankcase is connected by a pipe to a zone of reduced pressure or a zone of rarefaction. In naturally aspirated internal combustion engines, this is simply the intake manifold. If the engine is turbocharged, the crankcase breather is connected to the turbocharger inlet.

Any turbine has a line designed to drain oil. It connects to the engine lubrication system. In most cases this line is connected below the oil level in the crankcase. Therefore, when the pressure rises, the turbocharger oil cannot be removed normally. Also, this problem can be caused by a clogged separator. This is one of the nodes in the ventilation system. The pipe may also be coked.

Deformation of the cylinder head or its nodes

This is another reason why the intake manifold is in oil. There are several malfunctions of the cylinder head. Some parts of the cylinder head cannot fit tightly due to damage or wear. Nothing prevents oil from entering the sump. Often this problem can be accompanied by a white film in the oil, and the engine can also lose power. It is simply impossible not to notice these "symptoms".

Oil in the intake manifold: causes and remedies

Also noteworthy is the large output of valve guides in the cylinder head. If this is the case, then the valves are practically not lubricated, that’s where the oil in the intake manifold comes from. Also, the lubricant enters the cylinders, where it safely burns out.


Speaking about the failure of the cylinder head, overheating is worth mentioning as one of the reasons. Overheating is dangerous, as there is a serious risk of deformation of the block head. First of all, in such conditions, it is the head that suffers. Therefore, it is necessary to operate the engine as carefully as possible.

Cylinder head diagnostics

Deformations can be detected using special supports or visually. It is recommended to carefully inspect the engine for damage. If there are problems, a loose fit of parts to each other will be noticeable. But in most cases, visual diagnosis can be difficult. Then a direct path to a specialized stand.

Oil in the intake manifold: causes and remedies

You can determine the output to the steering valves by the knock of the valves that accompanies the operation of the engine. By eliminating these causes, you can solve the problem of oil in the intake manifold.


The intake manifold is attached to the power unit with gaskets. This prevents possible air leaks. Also, the gasket allows you to limit the ingress of oil into the manifold. But over time it can be damaged. In this case, the oil still gets there. Because of this, the engine may start to stall. If there is a mass air flow sensor, the ECU will give an error. All this suggests that the gasket under the manifold is damaged.

There can be many reasons for failure. Very often these elements fail due to wear. Sometimes the gasket is destroyed due to overheating. However, modern elements stably withstand high temperatures. Sometimes the gasket is damaged during the installation of the engine.

Getting rid of the oil in the intake manifold in this case is simple – you just need to replace the gasket. Then the collector is reset. But some nuances must be observed. Thorough cleaning of engine and manifold surfaces is recommended. Nuts are removed with a strictly defined moment.


Before talking about why the turbine drives oil into the intake manifold, it is necessary to recall its structure.

Oil in the intake manifold: causes and remedies

Roughly speaking, the compressor has a primitive design. It is an axis on which two combs with blades are installed. One of the combs is driven by exhaust gases. The other rotates due to the fact that it is on the same axis. The number of revolutions can be high, so the shaft must be equipped with quality bearings. But as practice shows, dry bearings do not withstand operation in a turbine. The part is very hot, as a result, the assembly overheats and seizes.

For the assembly to work efficiently, it was necessary to somehow eliminate excess temperature and improve slippage. Oil is great for this. Attached to the shaft are two lubrication channels for each bearing. So you can get high speed and high performance.

Everything would be fine, but this design caused the emergence of many problems that cannot be solved today. And the most difficult of them is due to the fact that the turbine throws oil into the intake manifold.

Why does the turbine drive oil?

If something interferes with the normal operation of the turbine, then it begins to pump oil. This is not the most serious malfunction, but much depends on the compressor model and the type of malfunction. But the damage must be found and repaired. After all, even if you put a new turbine and do not eliminate the cause, the new turbine will suck oil into the intake manifold.

Indirect causes can be found and eliminated independently. Turbines often push oil due to pressure disturbances. Retaining rings can no longer do their job properly. The pressure drops and the oil becomes easier to use.

Oil in the intake manifold: causes and remedies

When gaskets and seals are worn, grease can enter the sump during turbine operation. This happens actively, since a lot of oil is pumped through the turbine. As a result, it overflows from above. This is shown very clearly. There is oil not only in the intake manifold, but also in the candles. The only way to remedy the situation is to repair the turbine.

The repair itself and its features depend on the model of the car. Repair kits are available for some turbines. This allows you to avoid unnecessary expenses and get the node up and running again very quickly. This work is done independently. But there are models for which spare parts manufacturers do not produce, and then the part has to be completely changed.

Air filter dirty

The complicated air intake for the turbine is one of the reasons for the malfunction. Often the air filter is to blame – they forget to change it. The air intake ducts can also be partially blocked. It can be pinched or broken.

When the turbine is running, a vacuum is created. If there is not enough air, the pressure increases significantly, oil is drawn out of the turbocharger.

Oil in the intake manifold: causes and remedies

The air filter is very important for the turbine. Basically, it drives grease due to the fact that the pressure is violated precisely because of a clogged filter. In turbocharged engines, the cleaning element must be changed every 8 thousand kilometers.


This is the second most common reason the turbine drives it into the manifold. The oil must be resistant to high temperatures. There is a special oil for turbines. It shouldn’t burn. Conventional oil cokes all lubrication channels.

Replacement should be more frequent. If the manufacturer recommends changing the oil every 12 thousand kilometers, then it is better to change it every 10 thousand. Then the resource of the turbine will increase, and there will be no oil in the collector.

Branch pipes

This is another reason. If the oil has not been changed for a long time, the pipes tend to clog. Even if the turbine is repaired, the nozzles are cleaned. It is very important. If there is oil under the intake manifold, then there is a pressure difference due to tubes or a filter. It is also important to monitor the tightness of the air elements, if there are cracks or other signs of deformation on the nozzles, they must be replaced with new ones.

Oil in the intake manifold: causes and remedies

Otherwise, there will be excessive air leakage. This is harmful to both turbocharged and naturally aspirated engines. The problem is aggravated by the fact that dirty air does not enter through these slots at all, bypassing the filter. And the presence of dust in the cylinders of the internal combustion engine causes premature wear of the piston group.


There are many reasons why grease enters the manifold. But all these symptoms can be eliminated with the help of diagnostics. Diagnosing the problem is not as difficult as it seems. Once the cause is found, it is important to fix the problem very quickly to avoid costly repairs in the future.

Post source: wekauto.ru

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