Signs of the need to replace the valve stem seals. What are valve stem seals? DIY removal and installation procedure

Quite often, you have to notice that increased smoke appears from the exhaust pipe of the car. Sometimes situations reach the point that the car is literally shrouded in clouds of thick smoke. It is quite obvious that to every motorist, the appearance of excessive smoke indicates the appearance of certain problems with.

Immediately, we note 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, it is not always easy for beginners to understand why the engine is smoking, as well as to establish the cause and identify rings or caps. Let's figure it out.

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There is 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 warm-up modes of a cold engine. Moreover, it is a mistake to believe that it is smoke. This is actually steam. Vaporized water is a natural product of the motor.

In an unheated exhaust system, this vapor partially condenses and becomes visible, with water usually appearing at the exit of the exhaust pipe. As the engine warms up, condensation decreases.

The colder the environment, the denser the steam is. At temperatures below 10 ° C, steam is formed on a well-warmed engine, and in freezing temperatures of minus 20 - 25 degrees, it acquires a thick white color with a bluish tint. The color and saturation of the steam is also influenced by the humidity of the air. The larger it is, the thicker the steam.

Note that if steam is visible during the warm season, it is quite possible that this is due to. Its shade depends on the composition of the coolant, weather, lighting, as well as the amount of coolant in the combustion chamber. Sometimes it can take on a gray tint, resembling "oily" smoke. But, unlike oil smoke, which leaves a bluish fog 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 the smoke. In this case, you can use a proven verification method. To do this, on a well-heated engine, briefly close the exhaust pipe section 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 traces.

If this simple test confirms that it is steam rather than oil smoke that is escaping from the exhaust system, action must be taken to correct the problem that is causing coolant to enter the cylinders.

Most often, liquid can enter the cylinders through due to insufficient expansion (in winter, coolant leaks at the junction of the block and the head are often observed), 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 a film of oil 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 sensor, the clutch or the fan itself, the condition of the radiator, its plugs, hoses or connections. If white smoke and accompanying defects are noticed, then the car cannot be operated, since the defects progress rapidly.

Let's go further. Black smoke from the exhaust pipe indicates an over-enrichment of the fuel-air mixture or deterioration of the fuel combustion conditions. Therefore, we are talking about malfunctions. Such smoke is usually clearly visible against a light background and is represented by soot particles - products of incomplete combustion of fuel.

Black smoke is accompanied by high fuel consumption, often poor starting, erratic engine operation, high toxicity of exhaust gases, and often a 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 ICE breakdowns.

Oil filler smoke *

Which can sometimes be seen, for example, if you open the oil filler neck while the engine is running. On a good (i.e., serviceable) engine, air will simply come out from there (as an option - with an admixture of oil mist, which is not a malfunction). If the engine consumes a lot of oil and strong smoke comes out of the throat, then the piston group is worn out. If the engine consumes oil, and from the throat it is clean, then the case may be (but, not necessarily) in the valve stem seals.

* So this symptom, rather, does not indicate wear on the valve stem seals.

The threaded part of the candles is coated with oil

This is also one of the symptoms of the need to replace the valve stem seals. However, not always. Those. it happens that the caps already need to be replaced, but the threaded part of the candles is still dry. Because there is still not too much oil in the combustion chamber, it has time to burn.

Why is the thread of the spark plug covered with oil when it enters the combustion chamber? It would seem that if there are gaps in the thread between the spark plugs and the block head, then they are minimal and do not exceed 0.2 mm?

Let's consider the process of engine operation. The fact is that at the moment of the admission of a portion of the combustible mixture, oil enters the cylinder, while there is a vacuum in the cylinder (as well as in the threaded gaps of the spark plugs). The mixture is then compressed. Naturally, it (including the oil and gasoline contained in it) begins to penetrate into all places where possible, including the threaded gaps of the spark plugs. Then the mixture is ignited and burned. It burns out almost everywhere, except, just, the threaded gaps. Because they are very small (in the region of 0.1 ... 0.3 mm), combustion, as a rule, cannot spread into such small gaps. As a result, oil accumulates in the threaded gaps. Gasoline evaporates because the candles are hot.

The candles are covered with black carbon. Increased smoke from the exhaust pipe

Carbon deposits can (but not necessarily) be oily. As a rule, when the valve stem seals are worn, it is terry. Although, too rich a mixture can also give a terry black carbon deposit. Blue-gray, sometimes black smoke from the muffler indicates wear of the cylinder-piston group, as well as an excessively rich mixture.

However, similar symptoms are observed when the valve stem seals are worn out (blue exhaust during gas overload), the ignition system malfunctions (the ignition timing is incorrect, high-voltage wires, distributor cover, slider, etc., and possibly a malfunction of the ... alarm), violation fuel system adjustments (e.g. carburetor, injectors, etc.).

Those. black smoke from a muffler and black-caked candles are not always indicative of an overly rich mixture. Both of these signs are also manifested both when the valve stem seals are worn and when the ignition system is broken. Why?

Because in the event of a malfunction of the ignition system, the spark on the candles will be defective, although in appearance it may be quite acceptable. Accordingly, the combustion of the oil-fuel-air mixture will also be defective. In particular, the oil and gasoline contained in the mixture will burn WORSE (than with a good spark), i.e. black carbon deposits will form, creating the appearance of an over-enriched mixture. For example, this was exactly what was observed in the case when it was "cleverly" pierced.

Alarm malfunction

It can also cause carbon deposits on spark plugs if ignition circuits run through it. A common case is when some connectors in the alarm have bad contacts (when they are old and / or made of Chinese metal). In this case, the ignition will be either excellent, then "not very", then (for a split second) will be absent altogether. And so - all the time.

There was a case when the car periodically stalled on the move after 10 ... 20 minutes of driving. And after - flatly refused to start. However, after the incident of 10 ... 15 minutes of parking, it started up as if nothing had happened and drove as long as needed.

Note: Exactly the same behavior of the machine in another case was the result of a malfunction of the valve stem seals.

In addition, the car often (but not always) stalled when trying to move uphill. The recommendations of the servicemen to repair the power system, of course, did not lead to anything at all. They only cost money and time to think. However, the problem was completely eliminated after restoring the electrical contacts in the two alarm connectors (by removing them and lightly crimping the connectors).

Why did the car start up after 10 ... 15 minutes of parking? Because during this time the signaling unit cooled down a little, the contact details of its connectors slightly changed in size (under the influence of thermal contraction), slightly shifted relative to each other (i.e., the “male” connector was slightly displaced relative to the “mother ”), There was a kind of scratching, slipping of their contacting surfaces relative to each other and contact was restored again for some time.

Why does the engine sometimes stall when driving uphill? Because in the alarm unit, located under the dashboard, when the orientation of the machine was changed relative to the vertical, the alarm unit moved slightly to a different position, as a result, the electrical contacts were sometimes broken. And when the car moved to a horizontal surface, the contacts were restored.

Smoky exhaust during gas re-gas

Symptoms of the formation of smoky exhaust during gas re-gasification are similar - both in the event of a malfunction of the valve stem seals, and in the event of a malfunction of the cylinder-piston group. The difference is that if the caps are faulty, then repeated re-gasings (4 ... 7 times) lead, as a rule, to the (temporary) disappearance of the smoky exhaust. Those. permanent smoke, as a rule, is not. Whereas in the event of a malfunction of the cylinders and pistons, the smoky exhaust does NOT disappear after several regurgations.

The reason is that in the first case, the oil accumulated near the junction of the edge of the valve stem and the valve stem, as a result of sharp pressing on the gas pedal, is TEMPORARILY sucked through the gap between the valve stem and the guide sleeve, into the cylinder, which leads to several smoky exhausts when peregazovki. When all the oil in the vicinity has been sucked out, no smoky exhaust (until the oil accumulates again) will not form. Whereas in the latter case, oil enters the cylinder regardless of whether the gas pedal is pressed sharply or not; no matter how many times and with what frequency it is pressed.

When idling, when the cylinders and / or pistons are worn out, the smoke will be thick and bluish (like in old Soviet motorcycles, Druzhba-type chainsaws), while when the valve stem seals are worn, it will be (at first) “bluish”. When viewed from above the exhaust pipe while the engine is running, it may not always be visible. But looking ALONG the exhaust pipe, when viewed from behind the car, sometimes (but not always) makes it possible to see such a bluish smoke.

Also, if the smoke from the muffler is white when the engine is WARM, then this is also a sign of wear on the valve stem seals, but not in the cylinder-piston group. By the way, another reason for the appearance of white smoke on a warm engine is the ingress of coolant into the engine cylinders due to a malfunction of the head gasket.

Note that the appearance of white smoke, which disappears after warming up, on an UNHEATED engine, on the contrary, is a completely normal symptom. Indeed, as a result of the combustion of the fuel-air mixture, in particular, water is formed. The vapors of which become visible until the engine and muffler warm up. For the same reason, water droplets can even fly out of the muffler. It often happens that water drips slightly from the end of the muffler pipe.

When the muffler warms up, water vapor on its walls will no longer condense - and the white vapor will disappear. The water will stop dripping.

A too rich combustible mixture will also give an exhaust of increased smoke, including during gas re-gasification. Which, it seems, SHOULD NOT disappear after repeated re-gasings.

However, in reality, not everything is so simple. There was a case when, due to a too rich fuel mixture, the car engine started up with great difficulty "hot" (while "cold" was started with half a turn). After repeated re-gasings, the exhaust of increased smoke (blackish) HAS DISAPPEARED. However, the problem was - precisely in the excessively enriched fuel-air mixture.

Increased fuel consumption

The fact is that the oil that gets into the cylinders when the engine is running makes it difficult for the fuel-air mixture to burn. Accordingly, in order to remove the required power from the engine, a larger amount of the mixture will be needed than in the absence of oil in the mixture.

By the way, not only valve stem seals, but almost all other engine malfunctions also lead to increased fuel consumption, whether it is wear of the cylinder-piston group, malfunction of the ignition or alarm system, suboptimal composition of the combustible mixture.

Drop in power and throttle response, engine dips

This is manifested in reduced dynamics when gaining speed, overtaking. And also "dips" can be observed when you press the gas pedal. Those. you press the gas, and the car SOMETIMES, instead of rushing forward, as it were, slows down, the engine stalls. Release the accelerator pedal or press it SLOWLY - the engine runs normally. In such cases, it is usually recommended to adjust or repair the fuel supply system. More advanced ones also recommend paying attention to the ignition system.

This is often true, but not always. Sometimes - with a sharp increase in the vacuum during the intake stroke of the fuel-air mixture (which is the result of a sharp pressing on the gas pedal), this vacuum is transmitted through the valve guides to the valve stem seals. If they are worn out, then a portion of oil is sucked in, which enters the cylinder, filling the spark plug, i.e. (at first - temporarily, and then - permanently) turning it off from work. This explains the "failure" in the engine. If the car is equipped with a catalytic converter, it "for some reason" will soon fail.

Oil gets dirty quickly

Yes, this, too, is one of the symptoms of valve stem seals wear, which is not well known to everyone. Why does the oil become dirty, becoming dark, then black? There are two main reasons, as a rule:

wear of engine parts and the ingress of wear products into the oil
the formation of carbon deposits caused by the combustion of oil contained in the fuel-air mixture and its subsequent flushing

Well, but very commonplace reasons, for example, a malfunction (or absence) of the air filter, as a result of which dust from the air enters the cylinders, which causes contamination of the oil or simply low-quality oil that quickly decays when the engine is running, we will not consider here.

The first, in principle, is generally known. But, at the same time, there should be metal particles on the magnetic oil drain plug. And if they are few or not at all?

Then, obviously, the black particles causing the oil to darken are nothing more than coke washed off the cylinder walls. Indeed, most modern engine oils contain fairly effective detergent additives, which help to wash off carbon deposits. If not for them, then as a result, the piston rings would simply coke. Quickly. Well, their presence in the oil saves the engine. True, the entire blow is taken over by the oil, which quickly becomes dirty.

Since carbon deposits are formed GRADUALLY, its particles are very small, they, being washed off the cylinder walls, freely pass through the oil filter and, for this reason, remain in the oil, causing the need for its accelerated replacement.

However, there may also be a mixture that is too rich. Which also gives black carbon deposits on the spark plugs as well as on the cylinder surface. Accordingly, after this carbon deposit is washed off with oil, it gets into the engine crankcase.

Glow ignition

It is expressed, in particular, in the fact that the engine continues to run for several seconds, or even more, even after the key is removed from the ignition lock. Yes, and this can also be a symptom of oil entering the combustion chamber, including as a result of a malfunction of the valve stem seals. Why?

Because modern gasoline cars, perhaps, without exception (both carburetor and injection) are equipped with a fuel cut-off system when the ignition is turned off. For example, if we talk about a carburetor car, then in carburetors, as a rule, there is an idle solenoid valve that blocks the flow of the working mixture when the ignition is turned off.

By the way, for reference, a modern gasoline car does not have to be an injection car at all. For example, many military vehicles are still carbureted. The reason is probably clear to you: military vehicles are required, among other things, to have increased reliability and high maintainability even in the "open field". It is clear that a knowledgeable person will be able to clean and adjust the carburetor quickly and in almost any conditions, while adjusting the injection engines cannot do without a computer. Well, cleaning nozzles in the “field” is definitely impossible without special equipment. And, in fact, the military will not carry a diagnostic computer and other devices with them just to use the injector, when it is quite possible to do with a carburetor that has proven its reliability and quick maintainability. Well, which slightly increases fuel consumption, slightly increases the toxicity of the exhaust gases. And nothing more.

Then, the more electronic parts there are in the car, the higher the likelihood of their failure, for example, when exposed to an electromagnetic pulse.

So, if the engine continues to run even when the gas supply is turned off at idle, it means that there is something in its cylinders that can burn out. In this case, it is nothing more than oil. Located there in SUCH concentration at which the engine is still able (but not always) to work. It is clear that when the caps wear out even more, oil will get into the combustion chamber even more, then the glow ignition may disappear. But, at the same time, the car will be difficult to start, there will be increased oil consumption, etc.

The car is difficult to start "hot"

If it is difficult to start "on cold", then the reason, often, is not at all in the valve stem seals. There are, most likely, more obvious reasons, such as wear of the cylinder-piston group, disruption of the fuel supply, malfunction of the ignition, including, as already mentioned, alarms. And also - a malfunction of the battery, starter.

But if the "cold" engine starts with half a turn, but on a hot one, paradoxically, you have to spin it up with a starter for 5 ... 10 seconds or even more (or even the car engine stalls as soon as it warms up properly), then the reason for this may well be wear on the valve stem seals.

The fact is that in a cold engine the oil is naturally cold too. And having a high viscosity, and therefore - reluctantly seeping into the gap between the valve stem and the working edge of the valve stem seal. When the oil warms up, its viscosity decreases (sometimes by several orders of magnitude), and it is much easier for it to pass into this gap.

However, a violation of the composition of the combustible mixture, ignition malfunctions, alarms are also not excluded, of course.

Exhaust gas has a very disgusting, suffocating odor

It is clear that the smell of exhaust gas is by no means natural, pleasant and safe.

However, having sniffed, say, the cars driving in the Arab Emirates (UAE), I concluded that the situation with exhaust gases there is MUCH (!) Better than in Russia. It seems that there is a continuous stream of cars, but the exhaust smell is insignificant ... Sometimes, even leaning close to the exhaust pipe, you somehow do not catch the nasty smell that comes from Russian cars. One of the reasons for this, of course, is better quality gasoline. Which, by the way, was also much cheaper than in Russia, at least until the moment when the ruble was sharply depreciated against the dollar and many other currencies.

Yes, it is, after all, the exhaust gas, what to expect from it. However, when the combustible mixture is of poor quality, incorrect (in particular, as a result of a large amount of oil getting into it), then, naturally, the exhaust smell becomes much, much more disgusting. In such cases - it is worthwhile to stand a little near the exhaust pipe while the engine is idling - and you want to get away from this smell somewhere. The neutralizer, we repeat, breaks down very quickly.

Therefore, if the car's exhaust has become somehow particularly unpleasant, suffocating, not the same as it was before, you should pay close attention to the engine parts through which an excess amount of oil can enter the combustion chamber. In particular, these are valve stem seals.

However, a very rich combustible mixture can also be the cause of such a smell.

Worn valve guides, valve stems

Of course, the wear of their working surfaces in itself does not indicate wear on the valve stem seals. He simply speeds it up, and significantly. It also makes it useless to replace the caps with new ones.

The fact is that if the holes in the guide bushings and / or valve stems are badly worn out, even a new high-quality valve stem seal will be unable to fully retain oil during engine operation. Which will enter the combustion chamber, as with worn caps.

So if, after replacing the valve stem seals, those symptoms of their wear remain, then you should think about repairing (replacing) the valves and their guides. And even about the overhaul (replacement) of the engine, because, as a rule, by that time, its other parts also partly deplete their resource. It makes no sense to change only the bushings and valves, if after another 20 ... 30 thousand you will have to replace the chain, sprockets (pulleys), rockers, pistons, rings, as well as cylinder boring, grinding of the crankshaft necks.

How to measure backlash in valve guides? If roughly and roughly, then the backlash can be considered large if, when the valve stem is rocked from side to side, it feels much higher than it was on a new (repaired) engine. If it is much higher than the typical perceived backlash for a particular engine model. Well, for a more accurate measurement, of course, it is necessary to remove the block head, get the valve, etc.

The engine valves operate under very severe conditions. Above them, the camshaft continuously acts on them, a lot of friction is created. And from below they are in an environment of high exhaust gas temperatures. The camshaft is, perhaps, more oil lubricated than other engine parts, as a result, it gets on the valves, through which it flows down to the combustion chamber. If this process is not hindered, the following will happen. The oil will mix with the air / fuel mixture in the cylinders and burn. This will lead to the formation of carbon deposits on the walls of the combustion chamber, on the pistons and piston rings - coking. The wear of the engine will increase and the characteristics of its operation and the quality of the combustible mixture will deteriorate. But the biggest problem is that carbon deposits form on the valve seat and valve head (on top of the flat part, the so-called "skirt"). The valve stops closing. Such a malfunction is a serious malfunction of the engine, which in a short time makes it inoperative.

Where are the valve stem seals

To prevent oil from entering the combustion chamber, valve stem seals are installed on the valves (they are also valve stem oil seals). The valve stem seals can be confused with the valve rings only in the name. How to find out, valve stem seals or rings? The caps are small rubber seals and the rings are large metal thin formations that fit perfectly into the grooves of the pistons (crank mechanism). While the valve stem seals are located where the valves and guide bushings are located, between them (and this is the gas distribution mechanism).

The valve stem oil seal is essentially a consumable in a car, but replacing such an element is equivalent to overhauling the engine, since it is impossible to change it without disassembling the internal combustion engine.

How many valve stem seals are in the engine? There are exactly the same number of them in the engine as there are valves. That is, if this is an eight-valve internal combustion engine, then there are, respectively, eight caps. When the valve moves to open and close the inlet / outlet, the cap removes excess oil from the stem (the narrower valve portion) so that the seating surfaces (that is, the portion of the valve that interacts with the chamber) remains dry. The valve stem seals are made of rubber, which wears out quickly under the influence of an aggressive environment.

Signs of wear on valve stem seals

Like any consumable, the oil seal has its own regulated time of use. The valve stem seals have a service life of 100,000 km. But as practice shows, the oil seals become unusable earlier than the scheduled time. This is evidenced by the appearance of the following problems:

carbon deposits on spark plugs,
reducing the engine oil level,
the appearance of gray smoke from the exhaust pipe when you press the gas pedal strongly.

The location of the valve stem seals

The most optimal solution is to install the valve stem seals recommended by the vehicle manufacturer.

Such symptoms on a car give reason to think about replacing the valve stem oil seals. To do this, of course, is better in specialized car services. The price of replacing the valve stem seals will fluctuate around 4-8 thousand rubles. How much do the valve stem seals cost? Relatively inexpensive, about 500 rubles each. Now you can calculate how much it costs to replace the valve stem seals. You can do the operation yourself. But please note that the oil seals are easily deformed if mishandled.

The first thing to do is to select the correct valve stem seals. Acrylate rubber is a more modern material than fluoroelastomer. The valve stem size can be calculated by measuring the diameter of the existing valve - this is for the inside. As for the models of oil seals (the external size can also be attributed here), then new ones can be installed on the old ICE, but on the new outdated one is not the best option.

Replacing valve stem seals with your own hands

For work you will need: set of keys, valve decanter, pliers for oil caps, mandrel. It is most convenient to change the oil caps on the dismantled cylinder head. It is possible to remove the valve stem seals without removing the head. To do this, it will be necessary to set the top dead center for each piston when removing the oil seals from the valves. Otherwise, the valves have every chance of falling into the cylinder, even if you hold them, besides, it will be extremely inconvenient when installing new caps without a stop.

Valve Seal Replacement Procedure

So, how to change the valve stem seals? The TDC is installed or the cylinder head is removed. For work, it is best to use a special tool for replacing the valve stem seals, but we will also look at how you can remove the valve stem seals without a puller. With the help of a desiccant, the disc and the valve spring are removed. Next, the oil seal is dismantled with special pliers for valve stem seals (some use pliers as a valve stem seals remover with their own hands, but it is worth considering the risk of damaging the valve stem when using a non-specialized tool). A new oil seal is hammered into a new oil seal with a special mandrel for the valve stem seals (you can replace the mandrel with a metal tube of a suitable diameter, but it is highly undesirable). For easier movement, the stem and inner surface of the rubber element can be lubricated with engine oil. The blows should be light and accurate, since this part is fragile and subject to deformation. The installation of the valve stem seal into the seat is indicated by a dull sound. The same is done with the rest of the valves. After the new valve stem seals are installed, the return mechanism dries up again, the cylinder head is assembled, and other attachments are returned to their place. The operation is over.

Finally

After replacing the valve stem seals

To increase the life of the oil seals, special valve stem seal additives are used. Some of them act on the rubber part, softening it, while others are aimed at sealing the resulting gaps. If the use of additives to restore the valve stem seals still has its effect, then the restoration of the valve stem seals removed from the engine does not make sense at all, since their service life will be short, which means that in the near future you will have to spend again on the procedure for replacing them, which is completely unprofitable.

If, after replacing the valve stem seals, the problem was not resolved, this means that the replacement was performed incorrectly (rarely) or the malfunction was different (often).

A frequent question from car owners: "Why does the car smoke after replacing the valve stem seals?" Most likely, it was not the caps that needed to be replaced, but the oil scraper rings already mentioned above (their functions are similar).
How to check valve stem seals? Some motorists check what exactly is out of order, caps or rings, as follows: if smoke comes out of the exhaust pipe for 1-2 minutes, then these are caps, and if they do not disappear at all, then these are rings.
You should not neglect this operation, or postpone it until later. Indeed, behind the failure of small rubber oil seals there are large malfunctions of larger units of the internal combustion engine, up to a complete stop of the “heart of the car”.

In the design of any engine, both a domestic car and a foreign car, there are valve stem seals (valve seals).

They are always used when the machine is running, and therefore wear out very quickly. Increasing their service life is a headache for engineers working at automobile factories, but the timely diagnosis of signs of wear on valve stem seals, as well as their replacement, is already the task of motorists. It is possible to cope with it successfully only in one case, when these very signs are known to you, and if not, then this article will help you.

How do valve stem seals work and when are they considered worn out?

As you know, the valve in the engine is located in two different cavities. One of them implies the presence of engine oil in it, the other, on the contrary, must be isolated from it. In this case, the valve is in constant motion during its operation. In order to maintain the tightness of the hole through which it moves from one medium to another, valve stem seals are just needed. They are made of special elastic rubber, but this rubber tends to age, harden, dry out and collapse over time, as a result, the caps cease to cope with the task assigned to them and begin to need replacement. The car owner can determine this moment by special characteristics.

The main signs of wear on the valve stem seals.

Increased oil consumption - if engine oil is consumed in your car more than it should be, it means that somewhere it is used in vain, as an option, it gets into the combustion chamber due to worn valve oil seals.
Spark plug oil deposits are caused by oil entering the cylinders.
Blue exhausts when the car warms up, the engine heats up - the smoke disappears. Such a phenomenon is a clear sign of a cracked cap, which, heating to a certain temperature, becomes wider and begins to successfully cope with the functions assigned to it again.

However, be extremely careful, these signs may indicate not only worn valve stem seals, but also other problems with the engine! Therefore, at the time of diagnosis, do not forget to pay attention to:

mileage - as a rule, oil seals need to be replaced every 70-80 thousand km. mileage;
compression - if it is reduced, but you did not find any leaks or problems with valves and / or rings on the pistons, then the problem is definitely in the caps. They should be replaced.

Consequences of driving with worn valve stem seals.

If you missed the moment of failure of the valve seals, then most likely it will lead to the following consequences:

increased oil consumption, which, firstly, will not have the best effect on your budget, and secondly, will provoke periodic oil starvation, leading to increased wear of parts and the need for premature engine overhaul;
oily and ultimately spark plug failure;
burnout of valves - carbon deposits will form wherever there is oil, including on the cylinder walls, which over time will interfere with the closing of the valves and lead to their burnout.

To prevent all this from happening, carry out a timely replacement as soon as you notice the first signs of wear on the valve stem seals.

We will not consider the procedure for replacing the valve stem seals now, this is a topic for a separate article, but we will finally name the main recommendations that will save you from mistakes. There are only 3 of them:

to dry out the valves, always use a special tool - a desiccant, so you will have less chance of breaking or losing something;
when changing the caps, cover all openings on the engine with a rag or foam rubber, they will protect open cavities from dirt and you from losing crackers;
be sure to lubricate the new cap with oil before installing.

And remember, if you do not have enough experience and knowledge in replacing valve seals, noticing signs of wear, do not experiment, but hand your car into the hands of professionals, they will quickly replace the failed parts with new ones and take a little in this case. Depending on the car and service station, the costs will be from 7 to 20 thousand rubles.

Video.

The valve stem seals, or valve seals as they are also called, 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 the valve stem seals are, but also the reasons and the first signs of their wear.

What are the valve stem seals for?

In total, 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 leads to a constant oily mist in this area. The reverse, flat part is located in the area where a suspension of small drops of gasoline is always standing - this is the inlet valve; or, in the area of hot exhaust gases, it is an exhaust valve.

For proper operation of the camshaft, lubrication is simply necessary, but the ingress of engine oil itself into the combustion chamber is completely undesirable. And that's why the valve seals were created. So, during the reciprocating operation of the valve, the 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 through the valve stem, the oil is mixed with the fuel-air mixture. When the mixture flares up, the oil burns to form carbon deposits on the top of the "poppet" and on the valve seat. And this, in turn, leads to the fact that the valve loses its ability to close. The same carbon deposits remain on the cylinder walls, on the upper plane of the piston and on the piston rings. All this leads to the so-called "smokiness", which increases engine wear and the quality of its work. Besides, oil trapped in the combustion chamber impairs 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 valve stem seal

As you may have guessed, valve seals work under very tough and challenging conditions. In order to find them in the engine, a lot of time and labor will not be required. 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, calculating the number of caps is not at all difficult - there are exactly as many caps as there are valves in the motor.

It is interesting!Filling PAO (PolyAlphaOlefins) engines with synthetics made on a base oil of the 4th group, you lead to the fact that the oil begins to ooze through the gaskets and oil seals. Despite the advantages, due to the chemical properties of oils of the 4th group, PAO oils lead to the fact that gaskets and oil seals simply "dry out" during operation.

Valve seal design

There are only two options for the valve stem seal design. First option Is a lip device that fits over the portion of the valve guide that protrudes from the head.

Such caps are widely used because they are simpler and cheaper. But if you need to replace such caps, then it is very difficult, and sometimes impossible, to do this without special tools and skills. Second option the gland is mounted already under the valve spring, the work of which holds the cap on the head and seals its joint with the head.

The valve seals of the second type do not come into contact with the valve guide sleeve, they heat up less, and therefore are more durable. Another advantage of such valves is that, if necessary, they are easy enough to replace, 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. 2

The high efficiency 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 secondary rubber, then it has a higher degree of sealing.

You just have to know which caps are installed in your engine. And also, in the 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 on valve stem seals

the motor rotates at a speed of 500 - 4500 rpm, which means that each valve performs 150 - 1200 working strokes per minute. And this does not take into account the fact that during operation the valves are exposed to aggressive chemical attack from 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, the valve seals will need to be changed, despite their quality. But there is no need to do this every year. In order to keep the valve seals in good condition, it is necessary to use quality engine oil.

The first signs of wear on the oil valves are:

- the appearance of gray 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 formation of deposits on candles.