Signs of a malfunction of the Chevrolet Rezzo valve stem seals. Replacement of valve stem seals

29.08.2020

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.

Among the possible causes of increased oil consumption can be noted, in order of difficulty of elimination:

oil leaks through leaks in gaskets, seals, as well as cracks in the engine crankcase, cylinder block, oil pressure sensor, etc.
oil seal wear
wear of the cylinder-piston group
oil burnout due to its poor quality

The first group of causes is determined by visual viewing. Eliminating such causes, with the exception of the HEAD gasket and cracks in the cylinder block, is quite simple. It is only necessary to replace defective parts (seals, gaskets). The exception is here - the head gasket and the cylinder block. To replace them, it is necessary to remove the camshaft (with all the ensuing consequences), and then the head itself; and then completely disassemble the engine. Of course, such an operation will not be difficult for an experienced mechanic, but for an ordinary motorist ...

The second reason is the wear of low-removable caps. We will talk about the signs of the need to replace them a little lower. This operation also implies, as a rule, the removal of the camshaft (one or more - depending on the car model). However, there are cars on which this is not necessary. However, these are quite rare cases.

Finally, the wear of the parts of the cylinder-piston group. To eliminate it, it is necessary, as they say, to overhaul the engine. As a rule, it is timed to coincide with other repair operations, namely: replacing crankshaft liners, repairing (grinding) crankshaft journals, replacing valves, replacing / reaming valve guides, not to mention replacing worn (by that time) valve rockers , valve springs.

Here we look at the signs that indicate symptoms similar to wear and tear. valve stem seals. Here is a list (perhaps incomplete):

Alarm malfunction

Smoky exhaust when regassing

Increased fuel consumption

Loss of power and throttle response, failures in engine operation,

Oil gets dirty quickly

glow ignition

Note that it is not necessary that all signs appear at the same time.

Smoke from the oil filler neck*

Which can sometimes be seen, for example, if the oil filler neck is opened on a running engine. 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 neck, then the piston group is worn out. If the engine consumes oil, and it is clean from the neck, then the matter may be (but not necessarily) in the valve stem seals.

* So this symptom is more likely not indicative of 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 valve stem seals. However, not always. Those. it happens that the caps already require replacement, but the threaded part of the candles is still dry. For there is still not too much oil getting into the combustion chamber, it has time to burn out.

Why is the threaded part of the candle covered with oil under the conditions 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?

Consider the process of the engine. The fact is that at the moment of inlet 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 candles). The mixture is then compressed. Naturally, it (including the oil and gasoline contained in it) begins to penetrate into all places where it is possible, including the threaded gaps of the candles. The mixture is then ignited and burned. It burns almost everywhere, except, just, for threaded gaps. For they are very small (in the region of 0.1 ... 0.3 mm), as a rule, combustion cannot spread into such small gaps. As a result, oil accumulates in the threaded gaps. Gasoline evaporates, because the candles are heated.

Candles are covered with black soot. Increased smoke from the exhaust pipe

Nagar 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 terry black soot. 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 also observed when valve stem seals are worn out (blue exhaust during regassing), ignition system malfunctions (ignition timing is incorrect, high-voltage wires, distributor cover, slider, etc. are “broken”, and also, possibly, a malfunction ... alarm), violation adjustments of the fuel supply system (for example, carburetor, injectors, etc.).

Those. black smoke from the muffler and black-coated candles are far from always evidence of an overly rich mixture. Both of these signs also appear both when the valve stem seals are worn out, and when the ignition system is disturbed. Why?

Because if the ignition system malfunctions, 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 soot will form, giving the appearance of an overly enriched mixture. For example, this is exactly what was observed in the case when it was “cunningly” broken.

Alarm malfunction

It can also be the cause of carbon deposits on spark plugs if circuits related to ignition pass 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, or “not very”, then (for a fraction of a second) it will be completely absent. 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 a 10 ... 15 minute parking incident, it started up, as if nothing had happened and drove as long as necessary.

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 removed after the restoration of electrical contacts in two alarm connectors (by removing them and lightly crimping the connectors).

Why did the car start after 10 ... 15 minutes of parking? Because during this time the alarm unit cooled down a little, the contact parts of its connectors slightly changed in size (under the action of thermal constriction), slightly shifted relative to each other (i.e. the “father” connector slightly shifted relative to the “mother” connector ”), there was a kind of scratching, slippage 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 relative to the vertical changed, 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, contacts were restored.

Smoky exhaust when regassing

Symptoms of the formation of smoky exhaust during regassing are similar - both in the case 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 regassing (4 ... 7 times) usually leads to the (temporary) disappearance of smoky exhaust. Those. There is usually no permanent smoke. Whereas in the event of a malfunction of the cylinders and pistons, the smoky exhaust DOES NOT DISAPPEAR after several regassings.

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

When idling, when the cylinders and / or pistons are worn, the smoke will be thick and bluish (like old Soviet motorcycles, Druzhba-type chainsaws), while when the valve stem seals are worn, it will (at first) seem to be “bluish”. If you look at the exhaust pipe from above with the engine running, it is not always 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 haze.

Also, if, when the engine is HOT, white smoke comes out of the muffler, then this is also a sign of wear of the valve stem seals, but not of 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 disappearing after warming up on a COLD engine, on the contrary, is a completely normal symptom. After all, 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 drops can even fly out of the muffler. It often happens that water drips a little from the end of the muffler pipe.

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

Too rich a combustible mixture will also give an exhaust of increased smoke, including during regassing. Which, it seems, SHOULD NOT disappear after repeated regassing.

However, in fact, not everything is so simple. There was a case when, due to a too rich fuel mixture, the car engine started with great difficulty "hot" (whereas "cold" started with half a turn). After repeated re-gassing, the exhaust of increased smoke (blackish) DISAPPEARED. However, the problem was - it was in an overly enriched fuel-air mixture.

Increased fuel consumption

The fact is that the oil that enters the cylinders during engine operation makes it difficult for the combustion of the fuel-air mixture. Accordingly, in order to remove the required power from the engine, a larger amount of 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 be wear of the cylinder-piston group, a malfunction of the ignition or alarm system, or a non-optimal composition of the combustible mixture.

Loss of power and throttle response, failures in engine operation

This manifests itself in reduced dynamics when accelerating, overtaking. And also there may be "failures" when you press the gas pedal. Those. you press the gas, and the car SOMETIMES, instead of jerking forward, it seems to slow down, the engine stalls. If you release the gas 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 vacuum during the intake stroke of the fuel-air mixture (which is the result of a sharp pressure 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 is also one of the symptoms of valve stem seal wear, which is far from known to everyone. Why does the oil become contaminated, becoming dark, then black? There are usually two main reasons for this:

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

Well, quite banal 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 oil pollution or simply low-quality oil that quickly collapses when the engine is running, we will not consider here.

The first is generally known. But, at the same time, there should be metal particles on the magnetic oil drain plug. And if there are few or none at all?

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

Since soot is formed GRADUALLY, its particles are very small in size, they, being washed off from the cylinder walls, freely pass through the oil filter and for this reason remain in the oil, necessitating its accelerated replacement.

However, too rich a mixture can also take place here. Which also gives black soot on spark plugs, as well as on the surface of the cylinder. Accordingly, after this soot is washed off with oil, it will enter 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 has been removed from the ignition. Yes, and this can also be a symptom of oil getting into 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 carbureted car, then carburetors, as a rule, have an idle solenoid valve that shuts off 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 injection at all. For example, many military vehicles are, as before, carbureted. The reason is probably clear to you: military vehicles are required, among other things, increased reliability and high maintainability even in the "open field". It is clear that a knowledgeable person can clean and adjust the carburetor quickly and in almost any conditions, while adjusting injection engines can not 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 get by with a carburetor that has proven its reliability and quick maintainability. Well, which slightly increases fuel consumption, slightly increases the toxicity of exhaust gases. And, nothing more.

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

So, if even when the gasoline supply is turned off at idle, the engine continues to work, therefore, there is something in its cylinders that can burn out. In this case, it is nothing but 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 are even more worn out, even more oil will enter the combustion chamber, 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 “cold”, then the reason is often not at all in the valve stem seals. There, most likely, more obvious reasons, such as wear of the cylinder-piston group, fuel supply failure, ignition malfunction, including, as already mentioned, alarms. And also - a malfunction of the battery, starter.

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

The fact is that in a cold engine, the oil is also, of course, cold. And having a high viscosity, and therefore - reluctantly leaking 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 smell.

It is clear that the smell of exhaust gas cannot be called natural, pleasant and safe.

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

Yes, after all, after all, 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 in it), then, naturally, the smell of the exhaust becomes much, much more disgusting. In such cases - it is worth standing a little near the exhaust pipe when the engine is idling - and you want to get away from this smell somewhere. The neutralizer, we repeat, at the same time fails very quickly.

Therefore, if the exhaust of a car has become somehow especially unpleasant, suffocating, not the same as it was before, you should pay close attention to engine parts through which excess 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 the wear of 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 not be able 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 wear remain, then you should think about repairing (replacing) the valves and their guide bushings. And even about the overhaul (replacement) of the engine, because, as a rule, by such a time, its other parts also partly exhaust their resources. It makes no sense to change only the bushings and valves, if after another 20 ... 30 thousand the chain, sprockets (pulleys), rockers, pistons, rings, as well as cylinder boring, grinding of the crankshaft journals are to be replaced.

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

The engines of modern cars have in their design a lot of very small, but very important parts for its proper functioning. If you do not find out in time that they have become unusable and do not take appropriate measures, then the consequences of this for the power unit, and, accordingly, the budget and nerves of the motorist can be the saddest. These "little things" include valve stem seals.

They are part of the design of the gas distribution mechanism (timing) of a car's internal combustion engine. Their dimensions are quite small and they are by no means located in plain sight, but inside the engine.

As you might understand, this article will be devoted to valve stem seals. Here you will learn why valve stem seals are needed and what are the signs of wear.

Valve and valve stem seals.

Oil seals are essential in engines to prevent oil and debris from entering the combustion chambers. They are often called valve seals, and this name fully reflects the role they perform.

Valve stem seals are located directly on the valve stems, and consist of three main parts:

Base;
Actually cap;
Spring.

The base is a sleeve made of steel. It plays the role of the frame of this part and gives it the necessary strength. The cap itself is the main element of the part. It is made from a special rubber resistant to high temperatures and friction forces. The cap is mounted inside the sleeve, and when mounted on the valve, fits snugly around the stem and removes oil. And the spring is mounted in a special annular recess of the cap and ensures its tightest fit to the stem.

As for the oil that these caps must remove, it is supplied to the gas distribution mechanism by an oil pump. It is designed to lubricate timing parts that experience friction and increase their resource. At the same time, its penetration into the cylinders through the valve groups is highly undesirable, since, when burned, it forms carbon deposits that accumulate on their walls.

It should be noted that in modern internal combustion engines, valve stem seals have to function in rather harsh conditions of high temperatures and increased mechanical loads. In addition, they are also negatively affected by the substances contained in the removed lubricating fluid. Therefore, manufacturers of valve stem seals use the most durable materials that are resistant to friction, thermal and chemical effects for their manufacture.

Wear of valve stem seals

Like any other part of an internal combustion engine, which regularly experiences a whole combination of negative effects of various kinds, valve stem seals gradually but steadily wear out. Their most loaded rubber part loses elasticity over time, cracks appear in it. In addition, over time and under the influence of high temperatures, the clamping force of the spring inevitably weakens. As a result, the wear of the valve stem seals leads to the fact that the oil is not removed from the valve stems and it enters the combustion chamber of the internal combustion engine.

As practice shows, the resource of valve stem seals installed in modern internal combustion engines is approximately 100,000 kilometers. After the car has passed this distance, they must be replaced. Experts also recommend changing valve stem seals in car engines that have been out of service for a long time.

In addition, it often happens that valve stem seals wear out prematurely for one reason or another. In such cases, they, of course, also require replacement with new ones. The fact that the time for this kind of engine repair has come is evidenced by several characteristic signs.

signs of wear

Valve stem seals.

The following signs may indicate wear on the valve stem seals:

Significantly increased oil consumption;
The appearance of soot on the electrodes of spark plugs;
The appearance of blue exhaust gases at the time of engine warm-up.

The increase in the "oil appetite" of the engine when the valve stem seals are worn is quite logical and understandable. The fact is that the lubricating fluid that they do not remove from the valve stems enters the cylinders and burns out. Accordingly, it is irretrievably lost from the lubrication system of the power unit, and the oil has to be topped up more often than usual.

As the oil burns, the blue-colored combustion products come out, coloring the exhaust gases in the corresponding color. When the engine warms up, the oil burns almost completely, so the blue smoke disappears.

In addition, if oil, not removed by caps, enters the cylinders, then its smallest drops also settle on the electrodes of the spark plugs. Accordingly, after combustion, carbon deposits form on them.

Consequences of wear of valve stem seals

As soon as the listed signs of wear of the valve stem seals begin to appear, you should check the gas distribution system of the car, and special attention should be paid to the valve stem seals. Experienced motorists do it on their own, less sophisticated ones go to a service station, where experienced specialists perform diagnostics.

It should be noted that it is strongly not recommended to operate the engine with worn valve stem seals. As practice shows, if you ignore this defect and do not eliminate it, then it is almost inevitable:

The power of the power unit will decrease;
At idle, it will begin to stall periodically;
Turnovers will "float";
Compression will drop significantly;
Carbon deposits will appear on cylinders, pistons and valve seats.

As for soot, its appearance is indeed a very serious "bell", since its formation may well lead to a very expensive overhaul of the power unit.

How to change valve stem seals?

If the car owner finds that the valve stem seals on his car are worn out, then they must be replaced. This procedure is successfully carried out by the masters of car service stations.

First, they let the engine cool down, after which they dismantle the timing cover. Next, they make appropriate marks on the camshaft and crankshaft, after which they remove the camshaft. At the next stage, the valves are “dried out” (that is, pushing springs are removed from them), faulty valve stem seals are dismantled from them. For this, specialists most often use either ordinary pliers, or a collet specially designed for this purpose. Then the valve stems are lubricated with oil, after which new valve stem seals are put on them. Further, the assembly of the gas distribution mechanism of the car is carried out in the reverse order.

What are oil seals for?

The movement of the piston in the cylinder is facilitated by the splashing of oil under the skirt. But a thin film of lubricant is removed by oil scraper rings, which are dressed on the piston. On the other hand, in the gas distribution mechanism, the contact surfaces are lubricated.

WATCH VIDEO

A kind of oil suspension is created under the head cover of the block. On the border of the cylinder and the cavity above it, the valve stem seals are located. Their task is to prevent oil mist and oil from the valve stem from entering the combustion chamber of the cylinder.

It is not difficult to guess, given the constant contact with the valves of the gas distribution mechanism, that the caps are under constant load. Each valve makes hundreds of movements per minute, and the oil is heated to high temperatures.

How many and where are they on the engine

Based on the purpose and work being done, it is easy to determine where the valve stem seals are located. If we consider the engine assembly, then the cap is dressed on the valve stem. Structurally, the part is a plastic part in the form of a sleeve made of a special stable material and a metal base.

WATCH VIDEO

The location of the valve stem seals in the engine during its disassembly is determined as the cylinder head, at the point where the valves enter the working chamber.

If the engine has 8 valves and 16 valves

You don’t have to puzzle over how many valve stem seals are in a 16 valve engine. The number of these critical parts is exactly equal to the number of valves. Those. if in an engine with 4 cylinders it is indicated that there are 2 valves per cylinder, then there will be 8 caps. In more modern engines, where there are 4 valves per cylinder, the number of seals will be 16. Provided that the engine is 4-cylinder.

Reasons for wear

Along with the constant mechanical action, the cap is subjected to the aggressive action of heated oil and impurities in it. Do not forget about hot exhaust gases at the onset of the exhaust stroke.

Over time, natural rubber roughens, the walls of the sleeve crack and wear out. Despite the fact that the maintenance schedule did not determine the exact interval for replacing the caps, if the corresponding symptoms appear, it is not worth delaying replacing with new parts.

How to determine if a replacement is needed

Among the main criteria that directly indicate the need to replace valve stem seals are:

Oiling the spark plug electrodes. Oil has the ability to seep into the combustion chamber.

Increased oil consumption. Compared to the traditional "appetite" of 1 liter/10,000 km, the same consumption increases to a liter for every thousand.

The appearance of blue smoke at the exhaust. Part of the oil has time to burn out during the compression stroke.

Sometimes there is a dilemma, which is the cause of blue smoke from the exhaust pipe. By mistake, wear of parts of the cylinder-piston group is often called such a reason. To finally decide whether you need an overhaul of the engine or replacement of valve stem seals, it is enough to check the compression. The normal value of this indicator allows you to confidently point to the caps.

By the way, for a short time the problem of increased oil consumption will be removed by the use of special tools. A special softening additive for valve stem seals will restore the functionality of parts for a couple of thousand kilometers. The additive is effective after 500-700 km of run after addition. Do not delay the repair, most likely similar symptoms of engine wear will reappear soon.

How to find everything you need for work

When contacting a service center, changing the valve stem seals is not difficult. However, this approach will mean for the owner of the car the option of performing work with the removal of the head of the block, which involves replacing the gasket and mounting bolts. And yes, it's a big time investment. This option means a significant overpayment.

The easiest option is to do the work yourself. To do this, it is worth preparing a tool for replacing valve stem seals and buying a set of consumables for one engine.

Which caps are suitable: sizes and price

When determining which valve stem seals are best for a particular motor, you should pay attention to the original kit. You will receive a quality product, and the price does not seem significant.

For example, a set of original spare parts for popular models costs from 1.3 thousand rubles. (Toyota Camry 2.4 l) up to 2.2 thousand rubles. (BMW X3 2.5 L). When compared with available analogues, changing valve stem seals is cheaper by an amount of 800 to 1200 rubles, respectively.

When choosing analogues, do not be too lazy to check the compliance of the parts by the VIN number, or ask the store manager for advice.

We select a puller

To successfully replace valve stem seals without removing the head, you will need to buy a special tool. As a last resort, you can borrow such a set from a neighbor in the garage.

To do the job, you will need a tool, better known as a cracker. When choosing, you should pay attention to the equipment indicating its suitability for use with a particular engine. The use of universal devices is also allowed. However, some station wagons are still designed for a certain type of engine - with an HV or SOHS layout.

The tool is designed to clamp valve springs by mechanical pressure. After removing the crackers, access to the valve stem seals opens.

Do-it-yourself removal and installation procedure

At the initial stage of the work, the car is de-energized, the ignition coil is turned off and the candles are unscrewed. The piston of the first cylinder is set to top dead center. Next, to change the valve stem seals, perform the following operations:

Remove the valve cover and all hoses. The rocker bolts are loosened.

We remove the rockers. At the same time, make sure that crackers do not scatter when removing from the axle. Do not remove the rocker arms from the axle and do not turn them over so that oil does not leak from the hydraulic compensator.

Install the puller and compress the spring. As a result, two crackers are released that need to be removed (it is convenient to use tweezers).

We remove the valve plate, we get access to the valve spring and washer.

We press out the installed part. It is possible to use either an impact collet or pliers to tighten the cap along the axis.

Before installing a new cap, check the play of the valve itself in the guide. If the indicator does not exceed 0.15-0.20 mm, install the valve back.

A new cap is put on the lubricated valve shaft using a mandrel. The spring and valve disc, crackers are returned in reverse order.

Use a torque wrench when tightening the rocker bolts. Often the tightening torque is set at 50Nm.

If it is necessary to change the valve stem seals in cylinders 2 and 3, the pistons must also be moved to the end position.

WATCH VIDEO

All modern internal combustion engines are equipped with a whole galaxy of special seals. One of them is oil seals. As you might guess from the name, they are associated specifically with the oil in the automotive unit. In general, it is more correct to call such caps valve seals. Their task is to prevent situations where excess oil enters the combustion chambers. Despite the fact that the valve stem seals are made of special rubber, their service life is quite large. In the event of wear of the caps, an increase in oil consumption can be observed, as well as the formation of carbon deposits in the engine and a deterioration in the stability of its operation. Let's figure out how long valve stem seals "live", how they are made and what affects their service life, when and how they need to be changed, and also deal with the peculiarities of choosing new products.

Briefly about functions

In the engine, there are 2 types of valves: exhaust, intake. Each of the valves is located so that its upper part is in contact with the camshaft. There is an oily mist on this side of the valve when the shaft rotates. The type of valve will depend on what is on the other side of it. If this suspension is from droplets of gasoline, then the valve is inlet. If the lower side of the valve extends into the exhaust area, then the valve is called exhaust.

Now back to the topic of valve stem seals. Since the camshaft requires a lot of lubrication to function properly, excess oil can seep into the engine's combustion chambers. This is highly undesirable. Valve stem seals, they are also valve seals, just serve as a barrier between the medium with a large amount of hot diluted oil and the combustion chambers. The oil that lubricates the stem during reciprocating movements is removed precisely by the valve stem seals.

Why are high demands placed on valve seals? Everything is very simple. Oil can enter the combustion chamber through the valve stem, where it mixes with the fuel-air mixture and burns. Modern oils have many additives and, in principle, do not burn out completely. When they burn, soot is formed on the valve seats, and the so-called. "plates". As soot accumulates, the valve simply loses its ability to close. Carbon deposits will also form on piston rings, cylinder walls and the upper planes of the pistons. All this leads to a serious acceleration of engine wear and a decrease in the quality of its work - the mixture simply will not burn properly. If the caps do not remove oil and are themselves exposed to an aggressive environment, they cannot be called effective.

The device and resource of valve stem seals

All sealing elements of the engine seem simple, even uncomplicated. Caps are no exception. As already mentioned, they are made of special rubber. They have a rather complex shape, and if you remember that high demands are placed on the quality of caps, it is easy to guess that they are not so easy to manufacture. Here are the elements they are made of:

Base. This is a steel sleeve that acts as a strong frame;

Spring. Without a spring, the edges of the cap will not fit snugly enough on the stem;

Cap. The main element of the valve gland. Made from acrylate or recycled rubber. In the past, PTFE caps were common. It is the cap that removes excess lubricant from the valve stem.

The use of rubber as the main material for the cap is due to the fact that it is resistant to chemically aggressive environments and high temperatures. Since manufacturers are interested in ensuring that engine seals are as durable as possible, they began to use this particular material. It cannot be called cheap, so many motorists consider the price of the final product to be too high. Coupled with advanced and rather complex manufacturing technology, valve stem seals are expensive but durable seals.

As for the operational resource, everything is not so simple here. Many companies produce analogues of valve seals, which may not be of such high quality as the originals. The point here is that the valve performs over 1000 cycles in 60 seconds. The temperature in this area is very high, and the caps are surrounded by hot oil and exhaust gases. If they are made of low quality materials or do not have the best geometry, their resource will not be large. Good valve stem seals can run over 100 thousand kilometers. If the car has been idle for a long time (over a year), then the oil seals will greatly lose their residual resource. This is due to the fact that the rubber begins to delaminate, and the material of the spring ages, because of which it ceases to press the cap with sufficient force.

Wear of valve stem seals

Determining the wear of the valve seals is not very difficult. Identifies primary and secondary signs of wear, although in some cases they may indicate wear on other engine components. We will consider these signs in the context of a possible failure of the caps. The primary signs that you can not help but pay attention to are:

Exhaust color change. The exhaust becomes thicker and takes on a white or bluish color;

The appearance of soot on operated spark plugs;

An increase in oil consumption (up to a liter for every thousand kilometers).

If any of the above is observed, the valve stem seals need to be inspected. The question of how to get to them, we will consider a little later. We must say right away that when the caps are worn, it is recommended to inspect the valves and the gas distribution mechanism. Secondary signs of cap wear include:

A noticeable decrease in engine power;

Reduced compression in the engine;

The appearance of carbon deposits both on the pistons and on the engine cylinders;

The appearance of "floating" revolutions and the occurrence of situations when the engine stalls at idle.

Secondary signs of wear are not so unambiguous, as they may indicate the failure of several engine components at once. In any case, if you observe the above, it is recommended that the unit be inspected by a specialist. Remember that the appearance of soot precedes the failure of the engine and further overhaul, which can cost a pretty penny - here it is better to play it safe and set aside a day for inspection by a specialist in automotive units.

Self-replacement of valve stem seals

We note right away that manipulations with the engine should not be carried out without having a specialized education and, of course, experience. If a motorist has discovered a failure of the caps and still wants to work with the engine on his own, then first he should familiarize himself with the manuals. The fact is that the process of removing and replacing caps will directly depend on which model of car and engine you have to work with. There are several stages of work that are the same for all cars:

Wait until the engine cools down;

Remove the cover of the gas distribution mechanism;

Make marks on the camshaft and crankshaft, then loosen the drive and dismantle the camshaft;

Remove the pushing valve springs ("dry out");

Using pliers, remove the oil scraper cap;

Lubricate the valve stem and the inside of the new caps with oil (before that, the spring must be removed from them);

After installing the stuffing box in the frame, with a quick movement, put it on the stem and press it in until it stops. It is categorically not recommended to use force - pressing should be carried out with light blows, gradually;

Put on the spring caps, then dry the valves;

Return the engine and timing elements to their place.

If the problem with valve stem seals has been observed for a long time, then you will also have to remove the cylinder head and clean the internal cavities of the engine from carbon deposits. It should also be noted that some valve stem seals are made in such a way that their dismantling without special skills and tools is almost impossible. If it seems to you that the replacement work turned out to be too difficult, do not persist - entrust this work to a specialist.

Which oil seals to choose

Almost all experts recommend purchasing and installing the same engine components that the car manufacturer uses. This recommendation is often violated, which, however, does not always have consequences. The fact is that with the development of technologies for the production of valve stem seals and the use of new materials, the final product may even exceed the original in terms of service life. This is usually true for caps under the engines of older cars. For example, rubber caps successfully replace fluoroplastic ones. We still recommend searching for auto parts by:

Vehicle parameters and, in particular, the engine;

Code of available caps.

So you will definitely find the right option for repair. Be especially careful when searching for caps by vehicle parameters. Everything is important here: model, complete information on the engine, year of manufacture of the vehicle. If the original was found, then it will be easy to find an analogue. When choosing an analogue, it is especially important to pay attention to the manufacturer, as well as the country in which the cap was produced (most manufacturers have factories in several countries). Do not forget that analogues are often faked. A fake is easy to identify by the absence of special security features (verification codes, QR codes, holograms), the poor quality of the caps themselves, often the color of the product, as well as the lack of branded packaging or discrepancies in the design of the packages.

As already mentioned in the previous paragraph, often analogues of valve stem seals can surpass the originals in terms of workmanship and service life. So, for example, factory caps for engines of Mercedes-Benz M110 and M123 models (fluoroplastic) can be replaced with more modern rubber counterparts. Choose from the following manufacturers:

Elring (Germany);

Ajusa (Spain);

NOK (Japan);

Goetze (Germany);

Victor Reinz (Germany-USA).

In fact, these are the same firms that supply their products to automaker factories. OEM-quality parts can be found under the names of the manufacturers' own brands. Unfortunately, valve stem seals from these companies are often counterfeited. Be especially careful when choosing analogues from Ajusa, Elring and Victor Reinz. Practice shows that it is the Spanish product that is most often counterfeited, as a result of which the manufacturer himself today does not have the best reputation.

Good analogues can be found in the catalogs of Musashi (Japan), Corteco (Germany), Stone (Japan-USA). We note right away that some motorists note the average quality of valve stem seals from these companies. Of the three companies listed, only the reputation of Corteco is spoiled by a large number of fakes that exploit the name of the German brand. As for the analogue from little-known packers, it will almost certainly be a product of one of the manufacturers from the list above. You should only be afraid of low-quality fakes.

To identify valve stem seals, you should get a branded product. Fortunately, today it will be enough to have at hand the photos found on the net. It is worth paying attention to several things. First, for labelling. For example, caps NOK (Japan) are marked with the code and the name of the manufacturer. Secondly, fake caps are often made in the wrong color. For example, complete with branded products, one cap is completely gray, and the second has a black element. In fakes, everything is simple - both caps will be gray. Thirdly, counterfeit products are almost always larger than branded ones. Often the outer diameter of fakes is 1.5 millimeters larger than the originals. And fourthly, pay attention to the price. Counterfeits are always cheaper. If the average market price of a cap is conditional $3, and you find the same one, but for $1, then it is highly likely to be fake.

The oil seal is an important element of the internal combustion engine. Cap failure should never be ignored. At first, this leads to increased oil consumption and engine operation in an abnormal mode, and over time, to its failure. Engine repair will cost ten times more than buying valve stem seals and installing them. Fortunately, both analogues and originals are quite easy to find. When purchasing these spare parts, carefully check their authenticity. The number of fakes is extremely high, and fakes are seriously inferior to the originals in terms of performance and can cause carbon deposits in the engine and increase oil consumption.