How and why there is emulsion in engine oil

Emulsion in the engine

Emulsion in the engine , as well as on the oil filler cap can appear for two reasons. The most innocuous, white emulsion can occur when the engine is not warmed up, when moisture from it, evaporating when warmed up, settles on the inner surface of the oil filler cap. But the second cause of emulsion in the engine oil, is much more serious – it means the antifreeze gets into the oil. Why this happens, what it threatens and how to get rid of emulsion read below.

Emulsion in the engine

Emulsion in the oil system you don’t have to worry about occurs only on the cap and neck, rarely on the top of the dipstick, in the off-season and cool weather on short trips. If it is hot outside or “mayonnaise” has formed on the valve cover and is visible inside the ICE or the dipstick is completely covered with such emulsion, you should look for the reasons.

It is not difficult to notice such oil condition – it is enough to check the oil level often, not only when the oil light turns on! Other signs of emulsion in the engine, like increased temperature, will be unnecessary.

Causes of Engine Emulsion

The main reason why emulsion forms in the engine and on the inside of the oil filler cap is the ingress of moisture into the oil. The more of it, the more severe the consequences. It can get there for two reasons:

  • In the form of evaporating condensate from the inner walls of the engine;
  • due to depressurization of the oil or cooling system.

Table of causes of emulsion and methods of its elimination.

Why does emulsion form? Causes of breakdown Checking and correcting methods
Condensate evaporation on the hot engine Insufficient warming up of the engine to operating temperature After starting, especially in winter, warm the engine up to +90°C before driving off
Stopping of slightly warmed up engine if emulsion is formed From 10 … 15 km or more drive with warmed up engine
Antifreeze in oil Puncture of the cylinder-head gasket Replace the gasket, tighten the bolts in the proper sequence and with the proper torque
Alteration of cylinder-head geometry Pressing, milling, cylinder-head cylinder-head grinding
Burnout of heat exchanger gasket Oil cooler gasket replacement
Damage to the cylinder block Repair or replacement of the cylinder block
Corrosion of liners Boring of the liners or replacement of them with new ones
Improper connection of cooling system Revision of system, connection according to scheme
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Condensation from air

When it’s just condensation in the engine, the emulsion usually only forms on the cap and edges of the engine filler neck. There should be no beige colored foamy mass in the oil itself. Such emulsion is formed due to temperature difference, when moisture, evaporating, settles on the filler cap, and during intensive engine operation it mixes with oil droplets. If the trip is short (up to 10 minutes), it will not have time to disappear. With condensate in the engine you can drive without fear. Such condensation evaporates after 15 minutes after warming up to engine operating temperature. If the car is constantly used for short trips, the emulsion on the cap will be almost constantly.

Antifreeze in the oil

When yellow or brown emulsion is not just on the oil cap or the edges of the neck, but is visible inside the engine, it means you should disassemble the engine and look for the cause, it should not be like that. You can’t drive with such oil mixture for a long time!

The causes of emulsion formation in the engine

Traces of emulsion on the surface of the oil filler cap

  • Disturbance of geometry of cylinder-head housing;
  • Breakage of the heat exchanger, penetration of its gasket;
  • damage of the engine cylinder block (usually some micro-crack);
  • corrosion of the engine liners or their mechanical damage (wear);
  • Incorrect connection of the cooling system to the throttle.

For VAZ cars of “classic” models, among other things, the problem may arise due to crumbling plugs, located on the cylinder head. For example, there are three of these plugs on the VAZ-2101 engine – two on the outer surface of the head and one on the outside.

Consequences of emulsion in the engine

The formation of foam emulsion in the oil can lead to the following consequences:

  • oil characteristics change;
  • engine parts are poorly lubricated (in particular main and connecting rod bearings, valves, cylinder walls, piston group), which causes reducing their service life and the service life of the whole engine;
  • engine power decreases.

If the emulsion in the engine is formed not in the oil system, but in the cooling system, it may lead to the following consequences:

  • frequent overheating of the engine, boiling of the coolant;
  • the emulsion clogs the pipes and hoses up to the critical level, when the circulation of the antifreeze is impossible;
  • reduction of engine and its separate parts life.

Therefore, if emulsion is forming in some parts of the engine, you should not “turn a blind eye” to it. Instead, it is necessary to find out as quickly as possible why it is forming and to perform repair measures.

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What to do if there is emulsion in the engine

When emulsion appears on the engine cover or on the control dipstick, the first thing to do is to perform a number of simple checks, which will allow you to find out the seriousness of the cause. To do this is simple. After starting the engine must warm up to working temperature about +80 ° C … +90 ° C and drive the car in a normal mode (you can “give a little gas”) for at least 10 … 15 km, and better a little more. And then look at the oil filler cap and dipstick again.

Note that the cap itself and the oil in the engine will be very hot, so unscrew the cap carefully! Better yet, wait a few minutes for the temperature to drop a bit.

Foam emulsion inside the engine that needs to be removed

If the inspection reveals that the emulsion has disappeared, then there is no need to worry, and the car can continue to be driven. Sometimes special low-emulsion additives (demulsifiers) are used to prevent thickening of the engine in winter or during the low season. They work on the principle of formation of a chemical reaction, which results in getting rid of the foam. Another good prophylactic option is to use an engine insulator.

But when the emulsion on the engine cover has not disappeared, and maybe even added, it means that it is necessary to check the oil and cooling system of the engine for depressurization. At the same time it is recommended to check the level of antifreeze in the expansion tank of the cooling system. If it regularly drops, it directly indicates that it “goes” into oil. In this case it is not recommended to use the car until all diagnostic and repair measures are performed!

How to flush the emulsion in the engine

Washing the engine from emulsion is necessary only if it is formed as a result of antifreeze in the oil. If it appears as a result of heating, it is not necessary to wash the emulsion, it is enough to warm up the engine well.

In order to wash ICE from emulsion and other debris (especially if the oil is already old) one shall use special flushing oils. Or it is possible to use “an old-fashioned” method. It is to mix solar oil and mineral oil (it is even possible to use waste oil) in volumetric proportions one to three. And then to execute two-three cycles of engine flushing at idle revolutions. If you use special flushing oil, it is usually enough to do one cycle of washing lasting 15-20 minutes. After that pour fresh motor oil and change the oil filter.

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Emulsion on the oil filler cap usually forms in winter or during the off-season. Emulsion in the engine in warm summer weather should be alarming. The first thing to do is to check the level of antifreeze in the expansion tank, white smoke from the exhaust pipe and also remember the modes the car is normally used in. Then warm it up well and drive 10…15 km, and then check the cap. Most often the reason for the appearance of emulsion is the accumulation of condensate on the hot engine, but it can also occur due to engine malfunction, then you will have to check the oil and cooling systems.

A white deposit on the throat of the valve cover.

Often in winter, during severe frosts, car owners who at least occasionally look under the hood of their car and check the engine oil level, could observe a strange whitish-brown deposit. It usually appears on the oil filler cap and directly on the dipstick itself. Inexperienced drivers are seriously worried, and the others rush to the nearest service station, and the experienced guys there can “condemn” the engine, and banal to change the cylinder-head gasket unnecessarily, but for money of a client.

Actually, what is this danger and what is the danger for the engine? I hasten to calm down all: the emulsion of water and oil, which has a color of yellowish-brown foam, poses no danger to the engine! It is a normal condensate, i.e. a liquid formed by the condensation of gas or steam. Where does it come from? Of course, from the humid air that enters the engine. That is why a “white deposit” often occurs in the cold autumn-winter-spring period.

Emulsion is formed in the crankcase ventilation system. I will not dwell on the crankcase ventilation system in detail, I will only note that the operation of your car engine, the same oil flow rate and injectivity largely depend on its correct functioning. In brief, the venting system is designed to equalize the pressure in the crankcase (note: drain crankcase gases) with the atmospheric pressure, which allows you to avoid oil leaks from the cylinder-head gasket, oil seals and even squeezing the dipstick oil gauge. In particular, BMW owners are often faced with replacing the crankcase breather valve (KVGV). This valve is used to regulate the pressure of the crankcase gases entering the intake manifold. At a low pressure the valve is open. When the pressure in the intake manifold is high, the valve is closed.

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The most common condition is the wear and tear of the valve diaphragm. Over time, it gets hardened and torn, resulting in a malfunction of the car engine (e.g. floating revolutions, decreased acceleration). But we will return to the formation of “white plaque”.

So, hot crankcase gases, which are formed in the SCC, contain water vapor. Remember the chemistry course: during complete combustion of hydrocarbon fuel, the end products are carbon dioxide (CO2) and water vapor. So, these same crankcase gases (note, rather water vapor from them) and condense on the cold engine valve cover, as well as other cold parts of the engine and, in contact with oil, form an emulsion. Here we come to a very important conclusion.

As you know, the engine often works in winter for a short time and does not warm up completely (it is good, if we drive 10 km to work in the morning). And exactly in unheated condition white emulsion can form quite a lot, and it becomes noticeable to an attentive car owner. As a conclusion: white deposit is a result of small runs in a cold time. We are not talking about any malfunctions. This, in fact, is confirmed by the specialists of the official Volkswagen service. “White emulsion on the dipstick and oil filler cap is a normal phenomenon in our winter and nothing needs to be done. Emulsion is caused by condensation on the parts of the engine that cool most quickly (valve cover and dipstick). The only recommendation is to allow the engine to warm up to operating temperature. The more condensate, the more short trips in cold time (note: without warming up of the engine to working temperature), – told us the head of service department of official importer Volkswagen Atlant-M Farzoighandel Vladimir Voitshonok. – The deposits themselves do not do any harm. As to possible complications in work of internal combustion engine, this question is more extensive. Short trips in cold weather without sufficient warming up lead to fast wear of engine parts. Therefore in such operating conditions it is required at least to change engine oil more often and to try to reduce driving short distances.”

How to fight emulsion? Firstly, you should not warm up the engine at idle for a long time in winter. The thing is that the crankcase ventilation system is little engaged at idle speed, besides full warming up at idle will take a very long time. It is necessary to start driving already after small warming up in 5-7 minutes. I have brushed snow from the car – and go! On the way, at gentle speed, the engine will reach optimum operating temperature much faster, than during the long idling of auto at a parking. However, such advice is specified in the manual of a car, and experts of official services ask to use it in practice. If you suspect a puncture of cylinder-head gasket and consequently, gas or antifreeze in oil system, it is necessary to examine the radiator of warmed-up car for bubbles, and also the crankcase of warmed-up engine for a significant white deposit directly in the crankcase. As a rule, the emulsion disappears on the valve cover after the engine has worked under load for a long time. For example, a long ride without stopping at a speed of 100-120 km/h will cause it to disappear.

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If you find abundant emulsion on the oil dipstick above the measuring divisions, it is not a reason to worry: crankcase gases break out and, mixing with oil when the temperature drops, lead to the formation of condensate. But if on the dipstick appears white foam or a thick layer of plaque, it is at least a good reason to be more concerned about the condition of the engine.

It is also important to pay attention to the color of the exhaust smoke. If it is thick and white, the probability of mixing of oil and antifreeze as a result of cylinder-head gasket penetration is very high. It is also not superfluous to watch the antifreeze level. If there is less antifreeze and the oil level is just the opposite, you have to at least have the cylinder head removed, the gasket and valve stem seals replaced. But even worse, when antifreeze getting in a combustion chamber causes corrosion of cylinder liner walls. A serious repair is impossible to avoid in this case. If its level has not increased, there is not a little of it, and the antifreeze does not become less, and in addition, there is an emulsion on a filler-hole lid, it is quite possible that the reason of it is low-quality oil or moisture condensation in it. I repeat, in winter this frequent phenomenon does not require taking emergency measures and with the increase of temperature it passes by itself.

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