Logo carsalmanac.com

Oil in the coolant expansion tank: causes, first signs and methods for solving the problem

Table of contents:

Oil in the coolant expansion tank: causes, first signs and methods for solving the problem
Oil in the coolant expansion tank: causes, first signs and methods for solving the problem

One of the most important systems in any car is the cooling and lubrication system. The engine is a node that is subjected to high loads. This requires high-quality cooling of parts and lubrication of rubbing pairs. In general, both systems are quite reliable, as they have a simple device. But sometimes motorists are faced with an unpredictable problem. There is oil in the expansion tank. The reasons for this phenomenon may be different. Today we will take a closer look at all of them.

oil in coolant


How to determine the presence of oil in the coolant expansion tank? The easiest method is to open the container lid and check the condition of antifreeze or antifreeze. But the problem is that modern machines do not require the executionfrequent work under the hood. Therefore, drivers may not look there for months. And the consequences of having oil in the coolant expansion tank are extremely serious.

To determine this in time, you can pay attention to the color of the exhaust. when mixing antifreeze and oil, the exhaust acquires a characteristic white color. In this case, the smoke cloud will increase under load.

The next method is a probe test. If you frequently check the engine oil level, you will immediately notice the presence of an emulsion instead of a lubricant. This suggests that mixing of two types of liquids has occurred. In some cases, the emulsion is also present on the oil filler cap.

in the expansion tank

What does this say? Reasons

On a serviceable car, such a problem practically does not occur (why exactly, we will consider a little later). The presence of oil in the coolant expansion tank can indicate serious malfunctions. Among them:

  • Crack in the cylinder head.
  • Crack in the cylinder block.
  • Behavior of block sleeves.
  • Poor oil cooler seal.
  • Cylinder head gasket failure.

Can an emulsion form on a serviceable car? As practice shows, such a phenomenon can really be, but very rarely. This is due to condensation, which is formed due to frequent short trips on a cold engine. Emulsion is a seasonal phenomenon, and this does not mean that a serious problem has occurred in the motor.malfunction.

However, in most cases, oil in the coolant expansion tank indicates problems with the block, head, or oil cooler.

What to do?

Do not pre-sentence the block or head. Maybe that's not the problem at all. If the engine design involves the presence of an oil heat exchanger, it is worth doing the following. You need to find the coolant inlet and outlet pipes and loop them with a tube.

Then you need to drive on such a car for about 50 kilometers. If the oil no longer enters the expansion tank, then a problem has been detected. In such a situation, it is enough to change the heat exchanger in which the breakdown occurred. We also suggest watching a useful video on this topic.

Gasket problems

If on an Opel car the oil in the coolant expansion tank turned out to be due to a broken gasket, in order to return the engine to service, it is enough to replace it with a new one. Such an operation is best performed at the service station. However, if you have certain car repair skills, you can replace the gasket yourself.

When doing DIY work, it is important to use a torque wrench. It is necessary to stretch the bolts strictly observing the moment. And the gasket should only be installed on a well-cleaned and degreased surface.

coolant expansion tank

If there is a crack in the cylinder block

This is the most serious outcome of events. In suchcase, the entire unit needs to be replaced. The procedure is rather complicated and expensive. The price is comparable to the cost of a whole engine from disassembly. Installing another motor or changing the block on the old one is up to each owner to decide individually. However, this operation is very difficult to perform on your own. The work requires not only experience and knowledge, but also the availability of special tools.

oil in a jar

Do I need a flush?

If oil is found in the coolant expansion tank, the cooling system must be flushed after any repair. The old antifreeze has already lost its properties. Due to the emulsion, it is impossible to ensure normal heat dissipation. What washes can be used? There are some good options:

  • "Abro" AB-505. According to reviews, this tool perfectly cleans the system not only from oil deposits, but also from scale and corrosion. How to use the product? It must be poured into the cooling system according to the proportion indicated in the instructions. After that, you need to start the ICE. It should idle for about 20-30 minutes. Then the mixture must be drained from the engine.
  • "Liquid Molly". Such a flush also perfectly removes the emulsion in the engine cooling system in the event of a gasket breakdown or for other reasons. The product is used in the same way. The composition is poured through the expansion tank into the system, and then the engine is started. It should work for 20 minutes. After that, you need to wait until the mixture cools down, and then feel free to drain it.
  • "Laurel". No less popular manufacturer of automotivechemistry. It is in great demand among Russian car owners. The line has a high-quality liquid for flushing the cooling system. It is used in the following way. Distilled water is poured into the system, and then flushing is added. The engine must run for at least 15 minutes. The liquid is then drained off. If the emulsion remains, the procedure must be repeated again.

You can also try the old-fashioned way. To do this, we need distilled water and citric acid. A solution is prepared in the following proportion: 300 to 500 grams of powder is added to 5 liters of water. After that, the engine is started and waited for 20 minutes. All this time it should work at idle. Then wait until the liquid cools down a bit, and then drain it. If some oil remains in the system, flushing must be repeated again.

in the coolant tank

Consequences of the presence of oil in the expansion tank of Opel and other cars

Specialists do not recommend using an engine with such an emulsion in the expansion tank. What consequences can this lead to? First of all, due to the mixing of oil and antifreeze, the oil filter is significantly contaminated. Then the water pump wears out. But the worst thing is that proper lubrication of the crank mechanism is not provided. If you continue to ignore the problem that has arisen, then this will lead not only to a significant development of cylinders, liners, but also to engine jamming.

When mixing antifreeze with oil, a negative reaction occurs between the additives that are in bothliquids. This not only reduces their performance, but also provokes corrosion of metal parts of the internal combustion engine. Engine parts are under increased stress. This also applies to bearings.

coolant expansion tank

The emulsion in the expansion tank of a diesel engine is especially terrible. In this situation, there is a risk of rapid corrosion of the cylinder walls. While the engine is off, some of the antifreeze may enter the combustion chamber. In addition, there is a risk of soot formation in the oil due to additive conflicts. Various deposits clog oil channels. The engine is experiencing "oil starvation".

Pay attention

If the oil channels were clogged due to the emulsion, it is necessary to flush not only the cooling system, but also the engine itself. If this is not done, some of the soot will clog into the new oil filter.

oil in the coolant tank


Now we know why oil gets into the expansion tank. Its presence in antifreeze is sometimes a very serious sign. The problem needs to be addressed immediately. Otherwise, further operation of the internal combustion engine threatens with strong wear and corrosion of critical parts. After performing repair operations, flushing is mandatory. Change antifreeze, oil and oil filter.

Popular topic