Quite often you have to notice that increased smoke appears from the exhaust pipe of a car. Sometimes situations reach the point that the car is literally shrouded in clouds of thick smoke. It is quite obvious that for every motorist the appearance of excessive smoke indicates the appearance of certain problems with.
We note right away that not always, but often increased smoke indicates serious. At the same time, it will not be difficult for experienced drivers to determine the cause by the color and composition of the exhaust. However, for beginners, it is not always easy to understand why the engine smokes, as well as to establish the cause and identify rings or caps. Let's figure it out.
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White or black smoke from the exhaust pipe
Let's start with the main types of smoke for a better understanding of the problem. So, white smoke from the exhaust pipe is quite normal for cold engine warm-up modes. Moreover, it is a mistake to believe that it is smoke. It's actually steam. Vaporized water is a natural product of the motor.
In a cold exhaust system, this vapor partially condenses and becomes visible, and water usually appears at the end of the exhaust pipe. As the engine warms up, condensation decreases.
The colder the environment, the denser the steam. At temperatures below 10 ° C, steam is also formed on a well-heated engine, and in frost at minus 20 - 25 degrees it acquires a thick white color with a bluish tint. Humidity also affects the color and saturation of steam. The larger it is, the thicker the steam.
Note that if steam is visible in the warm season, it is quite possible that this is due to. Its shade depends on the composition of the coolant, weather, light, and also on the amount of coolant in the combustion chamber. Sometimes it can take on a bluish tint, resembling "oily" smoke. But, unlike oil smoke, which leaves a bluish haze in the air for a long time, the vapor quickly dissipates.
It is quite difficult for an inexperienced motorist to determine by appearance what is the source of smoke. In this case, you can use a proven verification method. To do this, on a well-heated engine, briefly close the cut of the exhaust pipe with a sheet of white paper, while the condensed vapor in the form of water droplets will gradually evaporate when it hits the paper and will not leave obvious greasy marks.
If this simple test confirms that it is steam and not oil smoke coming out of the exhaust system, then you need to take measures to eliminate the problem that contributes to the penetration of coolant into the cylinders.
Most often, liquid can enter the cylinders through insufficient traction (in winter, coolant leakage is often observed at the junction of the block and head), burnout, and less often as a result of formation. By opening the radiator cap or, it is easy to detect the smell of exhaust gases and an oil film on the surface of the coolant.
All problems associated with white smoke from the exhaust pipe require the elimination of not only direct causes, but also a mandatory check of systems that can affect their appearance: the switch on sensor, the clutch or the fan itself, the condition of the radiator, its plugs, hoses or connections. If white smoke and its accompanying defects are noticed, then the car cannot be operated, as the defects progress rapidly.
- We go further. Black smoke from the exhaust pipe indicates a re-enrichment of the fuel-air mixture or a deterioration in the combustion conditions of the fuel. Therefore, we are talking about malfunctions. Such smoke is usually clearly visible against a light background and represents soot particles - products of incomplete combustion of fuel.
Black smoke is accompanied by high fuel consumption, often poor starting, unstable engine operation, high exhaust toxicity, and often loss of power due to a suboptimal air-fuel mixture.
It is important to understand that monitoring the symptoms and quickly identifying the problem will further reduce the cost of repairs and avoid serious and rapidly progressing engine breakdowns.
Read also
Why are piston rings stuck? The main signs for self-identification of a malfunction, diagnostics. Do-it-yourself piston ring decoking.
The topic of the article is Niva valve stem seals. A little theory. The choice of a SPECIFIC run-in manufacturer, with whose products I work myself, during the repair and tuning of the cylinder head. Differences between the original and the fake. Features of installation and installation.
A bit of theory
The main task of the valve stem seals is to seal the pair, the valve guide. So that oil does not get into the combustion chamber, which is absolutely not needed there. By the way, caps are important only on the intake valves, since it is in the intake tract that a vacuum is formed. In the exhaust tract, we have excess pressure, therefore, by and large, valve stem seals play there, rather, a “decorative role”. In this regard, the Americans distinguished themselves, sometimes in a complete set of gaskets for the engine, NO caps for the exhaust valves at all. In the old, ancient times, caps were made of rubber, rubber and fluoroplastic. Now the materials are already completely synthetic. The most popular are Acrylic (working temperature range -40C to +180C) and Viton (working temperature range -40C to +250C). The second material is more modern and lasts longer. The choice of valve stem seals for our valves is very large. Elring (Germany), Goetze (Germany), Victor Reinz (Germany), Corteco (Italy). A couple of times I was let down by the quality of caps and cuffs made by Ajusa (Spain). After that, I do not recommend them. The Kirovchepetsk brand "reserve" has a very good price-quality ratio, but unfortunately it is very difficult to find original products. Sometimes on the forums you can hear the phrase, I put Audi or BMW caps on the car. This is a delusion, since automakers do not produce these articles themselves, but place orders and purchase products from the above-mentioned manufacturers of rubber products.
Valve stem seals Niva, German manufacturer Goetze
MC Goetze capsSince 2015, I have been working with this manufacturer, the German company Goetze. The brand is currently part of the Federal Mogul concern. Switched to it due to the completeness of the products. Each package contains 2 protective "condoms" for putting caps on the valve. And for some reason they stopped putting them in Victor Reinz boxes. This was the main reason for switching from one manufacturer to another. These valve stem seals are made for valves with a stem of 8 mm, therefore they are suitable for a wide range of engines (VAZ, UAZ, Gazelle). Experience and statistics have accumulated on them in a very large volume. In terms of quality, everything is as it should be - they do not tan in the cold, they bathe painlessly in gasoline and hot oil. In general, they do what MC caps are supposed to do. At the moment, only Japanese NOK caps can be cooler, but I did not find their products for valve data. Probably because the 8 mm valve in Japanese engines is the Mesozoic era.
Installation and operation
The valve stem seals receive the largest amount of damage during the process of illiterate installation.
- Be sure to use a special mandrel when installing them. A lot of Papuan services use suitable heads from a set of keys for this and “bury” the caps already at the installation stage.
- Use the plastic "condoms" that come with the kit.
- Before installation, send the caps to “bathe” in oil so that there is no dry installation element and scoring of the working edge.
- When installing, use a 100g hammer, it is quite enough.
Valve stem seals Niva, replacement interval
The AvtoTAZ operating manual recommends replacement after 50 thousand km. This is about 2-3 years of average mileage. The D'Artagnans at the minders' forum argued until they were hoarse about the fact that if these are the same caps that we put on the "Germans", then they can be changed no earlier than after 100 thousand km. The answer is simple, that's precisely because "on the Germans"))). What the plant is doing now and calling it engines is sabotage and sabotage. On any other car, the valve-guide clearance should be up to 0.04 maximum. To avoid incidents associated with bad metal valves and guides, the plant makes this gap more than 0.1 mm, that is, 10 acres. With such “tolerances and fits”, valve stem seals simply do not live more than 50 thousand. Therefore, the plant carefully and gently makes a substrate for itself.
Fake and original
Be careful when buying, there are a lot of fakes. Usually when you look at the photo of the packaging on the Internet, you already understand that this is crap. Not even a verification code. Since I bring parts from European warehouses and Scandinavian warehouses, I have nothing to be ashamed of. I will list a few features of the original products:
individual code - EACH package of caps has its own individual code. Even if there is no computer at hand, just take two packages, the codes should not match.
- A hologram is pasted on the package, this is not just a “glitter”. Four digits from the hologram must match the extreme digits of the digital code.
- If you have a computer, on the manufacturer's page, you can enter a digital code and verify the originality of the product.
Oil seals, or, as they are also called - valve seals / valve seals, primarily prevent excess oil from entering the engine. Just like most engine parts, they are made of special rubber and wear out over time and work less efficiently: they separate and allow excess oil to pass through. And this, in turn, leads to an increase in oil consumption. Today we will try to understand not only what valve stem seals are, but also the causes and first signs of their wear.
What are oil seals for?
There are two types of valves: inlet and outlet. The top of any valve is positioned so that it is in constant contact with the camshaft, the rotation of which results in a constant oily mist in that area. The reverse, flat part is located in the area where there is always a suspension of small drops of gasoline - this is the intake valve; or in the area of hot exhaust gases, this is the exhaust valve.
For proper operation of the camshaft, lubrication is simply necessary, but getting the engine oil itself into the inside of the combustion chamber is completely undesirable. And that's what valve seals were made for. So, during the reciprocating operation of the valve, oil is removed from the stem by a kind of skirt, which is the valve stem seal.
Principle of operation. When oil enters the combustion chamber along the valve stem, the oil mixes with the fuel-air mixture. When the mixture flares, the oil, burning, forms carbon deposits on the top of the "plate" and on the valve seat. And this, in turn, leads to the fact that the valve loses its ability to close. The same soot remains on the walls of the cylinder, on the upper plane of the piston and on the piston rings. All this leads to the so-called "smokyness", which increases engine wear and the quality of its work. Besides, Oil entering the combustion chamber degrades the combustion characteristics of the fuel-air mixture. Therefore, very high requirements are imposed on the condition of the valve stem seals.
Where is the oil seal located
As you may have guessed, valve seals work under very harsh and difficult conditions. In order to find them in the engine, a lot of time and labor will not be needed. This cap is located directly on the valves themselves - this is an assembled option; or in the head of the block - this is if the engine is disassembled. Well, it’s not at all difficult to calculate the number of caps - there are exactly as many caps as there are valves in the motor.
This is interesting!By pouring synthetics made on the base oil of the 4th group into PAO (PolyAlphaOlefins) engines, you cause the oil to begin to ooze through gaskets and seals. Despite the advantages, PAO oils, due to the chemical properties of oils of the 4th group, lead to the fact that gaskets and seals simply “dry out” during operation.
Oil cap design
There are only two options for the designs of valve stem seals. First option is a sleeve device that fits over the part of the valve guide that protrudes from the head.
Such caps are widely used, as they are simpler and cheaper. But if you need to replace such caps, then without special tools and skills it is very difficult, and sometimes impossible, to do this. Second option The stuffing box is mounted already under the valve spring, the work of which holds the cap on the head and seals its joint with the head.
Valve seals of the second type do not come into contact with the valve guide, heat up less, and therefore are more durable. Another advantage of such valves is that they are quite easy to replace if necessary, and they do not require special tools. But there are also downsides. Their price is several times higher, and the length of the guide sleeve is shorter, which leads to a decrease in wear resistance. Fig. 1. 2
The high return of the valve stem seal depends not only on its design, but also on the material from which it is made. If the cap is made of acrylate or secrubber, then it has a higher degree of sealing.
You simply must know which caps are installed in your engine. And also, in case of replacing them, follow one of the basic rules: install ORIGINAL caps - those that are designed for a particular engine.
Causes and signs of wear of valve stem seals
the motor rotates at a speed of 500 - 4500 rpm, which means that each valve performs 150 - 1200 working cycles per minute. And this is without taking into account the fact that during operation the valves are exposed to the aggressive chemical attack of oil and exhaust gases. All this leads to the fact that the material from which the soft part of the cap is made hardens faster, and as a result, wear and tear of the working edges of the cap.
Over time, valve seals will need to be changed, regardless of their quality. But there is no need to do it every year. In order to keep the valve seals in good condition, it is necessary to use high-quality engine oil.
The first signs of wear on the sebaceous valves:
- the occurrence of blue smoke from the exhaust pipe (it can be short-term: only when starting or braking);
Increased oil consumption (up to 1 liter per 1000 kilometers);
The appearance of deposits on candles.
Valve stem seals or valve seals prevent oil from entering the combustion chamber through the valves. How many of them in the engine can be determined by the number of valves: 12 valves = 12 caps.
The valve stem seals are located directly on the valves. This rubber product is a consumable item and must be replaced periodically.
MSC location on 7a-fe
When to change
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Like any consumable item, caps require regular replacement. Masters advise changing the MSC every 50-70 thousand kilometers. This will avoid serious problems with the motor.
How to check the status? To the touch. If the seal is hard, it's time to change it.
Obvious signs of MSC wear:
- increased oil consumption;
- gray smoke from the exhaust pipe after starting the engine. Signals about the ingress of oil in the cylinder and its combustion;
- the appearance of oil on the threads of candles.
The first symptoms of wear indicate the need for an urgent replacement of the MSC.
Replacement
You can change the valve stem seals yourself or at the service. If you have experience in repairing Toyota cars and the right tools, you can replace it yourself.
In order to remove MSCs, you need a special tool called "valve cracker" and cap remover.
Which caps to choose is up to you. Now you can buy valve stem seals online at bargain prices. But it is better to purchase high-quality consumables so that you do not have to change them ahead of time. The main parameter for MSC is their compliance with your Toyota model. The price starts from 60 rubles apiece, depending on the engine model.
Installing valve stem seals with your own hands is not a difficult procedure, but it requires care and experience. During valve cracking, there is a danger of losing the cracker. After that, it will be impossible to assemble the motor back. You should also pay attention to protecting the engine from dirt during replacement. If you are not confident in your abilities, do not take it.
Example: replacing valve stem seals with 1zz-fe
How much does it cost to replace valve stem seals on your own and in the service, let's look at an example. Self-replacement will require tools and consumables.
Universal cracker - 850 rubles.
Oil scraper caps - 120 rubles * 16 pieces.
Puller - 200 rubles.
Repair will take a simple motorist at least half a day. Total: 2970 rubles. How to replace valve stem seals is described in detail in each vehicle manual. Toyota owners willingly share photos of their experiences in replacing MSCs.
The cost of replacing the service is from 1500 to 3000 rubles. Plus the caps themselves - about 2000 rubles. Total maximum 5000 rubles and 40 minutes of waiting.
Obviously, the replacement at the service is more expensive, but it also takes less time. In addition, a motor mechanic will cope with this task better than a simple car owner.
Additives for MSC
To avoid replacing consumables or delay it, you can use special additives. The additive for valve stem seals is designed to soften them, that is, to increase the service life of already worn MSCs. There are sealing additives that fill the gaps formed by time through which the oil passes.
Autochemistry of this kind is very popular due to its low cost compared to replacing MSCs. In addition, additives act on all rubber products, extending their service life.
How to check if the additive is working? If you have already used specialized auto chemicals, keep an eye on oil consumption. If it fell, the additive is effective. The best manufacturer of automotive additives is considered an American brand Wagner.
followed by German Liqui Moly.
Many motorists use domestic additives laurel.
Replacement of MSCs is much more effective than the use of additives. In the end, the seals will still have to be changed. In order not to harm the engine, contact a specialist.
Structurally, in an internal combustion engine, there are several types of seals that serve as seals for various movable joints, among which a special role is given to valve seals or, as they are also called valve stem seals.
Purpose
Protection of the combustion chamber from oil ingress from the cylinder head.
Oil is supplied to the head of the block under pressure to lubricate the camshafts, during the rotation of which an oil mist is created in the cavity of the head, consisting of splashes of hot oil deposited on all elements of the head of the block.
Where are they?
Guide bushings for intake and exhaust valves are installed in the block head. A certain thermal gap is left between the sleeve and the valve stem, designed to expand the parts when heated.
In order to prevent oil from the block head from entering the combustion chamber through this gap on the bushings, oil seals are installed in the form of caps, for which they got their name - “valve seals”.
Device
The gland is a steel cylinder for a hard fit on the head of the guide bushing. On top of the cylinder, a layer of rubber or rubber (fluorine or acrylate rubber) is vulcanized in the form of a truncated cone, to tightly wrap around the valve stem and remove oil during its working stroke. A spring ring is installed at the end of the cap for reliable contact of the cap with the valve body.
When do you need to change?
During the operation of the power plant, depending on the engine speed, every minute the valves perform about 200-1200 cycles, which negatively affects the resource of the caps, causing their natural wear.
Car manufacturers do not give any data on the frequency of replacing valve seals and this work is carried out as signs of their malfunction are detected.
Symptoms of a malfunction:
Oil on the threads of candles, with severe wear of the caps, oil is already present on their electrodes;
Power drop, deterioration in dynamics and increase in fuel consumption;
Unstable start of a hot engine;
With an engine, it is the caps that are the first to suffer, as they are the most highly located in the engine, plus those in contact with the valves heated in the combustion chamber. In such cases, the seals simply "tan" and are no longer able to do their job, allowing the oil to freely enter the combustion chamber.
A seal failure can also be detected when the valve cover is opened to perform adjustment work or replace the gasket. This applies to engines where caps can be seen. The malfunction will be expressed in the absence of a spring, or an oil seal that has “removed” from the guide sleeve and “sits” on the valve stem.
How is the replacement process going?
On many engines, valve stem seals are replaced without removing the cylinder head, only partially disassembling it to get to the oil seals.
However, if the engine has been running for a long time with faulty caps, then this definitely led to the formation of carbon deposits on the plates and valve seats, which must be removed for reliable engine operation.
In addition, in most cases, on the removed head, it is found that its plane is not parallel, which must be milled.
In any case, this work belongs to the category of complex and responsible and must be carried out in a car service, or in the garage of an experienced mechanic, where there are all the conditions and the necessary tools for its implementation.
However, there is a nuance here. Replacement will only be advisable if the valve stem bushings are not worn. Otherwise, the service life of new parts will be extremely limited and repeated repairs will be required.
The fact is that if the valve stem runs in a guide with a large gap, then it will not move in the center of the sleeve, but with a warp and constantly press on one edge of the cap, causing its intense wear.
What happens if it's not repaired?
As follows from the theory, for the combustion of 1 liter of gasoline, 14-16 kg of air is needed, and such an air-fuel mixture will be most favorable for the operation of the engine, both in terms of fuel economy and full power output.
When oil appears in this mixture, it leads to incomplete combustion, unstable engine operation, loss of power and increased fuel consumption.
In addition, during the combustion of oil, carbon deposits form on the valve plates, piston crown and spark plug electrodes. With a strong flow of oil, when the caps are no longer able to hold it, misfires appear, or one of them stops working altogether.
Soot on the valves - one of the consequences of faulty caps
The soot that appeared on the valve plates does not allow them to tightly “sit down” in the valve seats, which leads to a decrease in compression in the cylinders and interruptions in the operation of the power plant. Plus, a loose valve seat (especially exhaust valves) creates conditions for a breakthrough of hot gases from the combustion chamber and burnout of the valve disc.
If the above listed malfunctions are found, it is recommended, without postponing for a saving tomorrow, to contact car service professionals to extend the engine life.
