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.

Oil seals are necessary to prevent oil from entering the combustion chamber and are located between the timing valves and guide bushings.

The gas distribution system uses intake and exhaust valves. The top of the valve is always exposed to the oily mist generated by the rotation of the camshaft, while the bottom is in the midst of a suspension of gasoline vapor (intake valves) or heated exhaust (exhaust valves).

The normal operation of the camshaft is ensured by lubrication, but its entry into the combustion chamber must be prevented, otherwise the burnt oil forms deposits on the working surface of the valve, cylinder and piston. As a result, the engine will be coked: its performance will deteriorate, and wear will accelerate many times over.

Oil seals prevent the formation of carbon deposits: they remove oil from the stem so that it does not end up in the middle of a combustible mixture. The design of the stuffing box is quite simple: it is a rubber cap, inside of which there is a reinforced steel bushing and an expander spring, which provides high-quality grip between the cap and the stem. Of no small importance is the stuffing box material: modern manufacturers use acrylate rubber or secondary rubber - these materials provide good clamping quality.

When to change valve stem seals?

When the engine is running, the seals are subjected to a very high load. In addition to the purely mechanical impact, valve stem seals also have to withstand the aggressive effects of oil mixed with exhaust gases. Prolonged use of oil seals leads to the fact that the rubber begins to harden, resulting in abrasion of the working surface.

Of course, you can always say that valve stem seals are a consumable item, and wear is normal. This is true, but there is one inconvenient circumstance - it is quite difficult to change the seals. To get to them, you will need to perform a lot of extra steps.

However, the replacement of oil seals is not required so often: one set of valve stem seals on average “drives” about 100 thousand kilometers.

Oil seals: signs of wear

The fact that it is time to change the valve stem seals can be understood by the following signs:

1. Excessive oil consumption. Such a sign in most cases indicates wear of the seals. An increase in oil consumption is also noted when the piston rings are worn, but in this case, oil smudges can be found in the breather pipe.

2. An exhaust that has a distinct shade of blue. This symptom manifests itself due to the fact that oil immediately after starting the engine enters the cylinder and begins to burn, manifesting itself in the form of blue smoke coming from the exhaust pipe.

3. Uniform oil consumption regardless of operating conditions. If the oil does not flow into the breather pipe, and the flow rate is high and unchanged, the seals are clearly out of order, and they need to be changed.

4. Formation of soot on spark plugs. Increased wear of the valve stem seals leads to the fact that the candles are flooded with oil, up to the engine tripping.

The detection of one or more signs usually indicates that the oil seals are worn out. If the symptoms described above have been observed for a long time, then in the near future it is necessary to take care of replacing the oil seals, otherwise further driving can lead to disastrous consequences

Replacing valve stem seals without removing the head

The decision to replace the oil seals when signs of a malfunction are found is a very correct step.. Sometimes drivers try to solve the problem without "surgical" intervention, using various additives and additives that allegedly soften the rubber and extend the life of the valve stem seals. Such a decision should not be made: additives either do not have any effect on the material of the seals, or they soften them too much, as a result of which the wear of the rubber only increases.

Replacing oil seals without removing the head is a complex process, so you should devote a lot of time to it, and perform all actions very carefully. How to change valve stem seals? The algorithm of work is rather cumbersome, but all these operations must be carried out sequentially and very scrupulously:

1. First of all, you need to wait until the engine cools down, and all its elements go into "standby mode". After that, you can get to work.

2. The first step is to remove the timing cover. You need to act carefully so that the gasket is not damaged (you definitely should not pick the cover with a screwdriver).

3. Next, you need to set both shafts (crankshaft and distribution) according to the marks. Parts should be marked so as not to be confused when assembling the engine, and even better, write down all your actions. When removing the camshaft, loosen its drive. It is advisable to inspect the removed camshaft for wear - this will help save time and effort during the further operation of the car.

4. The next stage is the cracking of the valves. To do this, you should use a special device. The raskharivatel bracket must be fixed on the bed attachment stud, and its other end is installed with a ring directly on the valve spring plate. Pressing the lever, it is necessary at the same time to pull the crackers out of the plate with the help of tweezers. After that, you can remove the valve lifters.

5. Considering the fact that pistons 1 and 4 are at the top point, it is better to start replacing the seals with them. This is due to the need for support for cracking the valves - the pistons will provide it.

6. Having finished with cracking, it is necessary to remove the springs and the plate. Next, you need to take a collet puller and fix it on the cap. By moving the weight up the puller rod, you need to hit the upper stop, thus removing the cap reliably and without loss. It is worth refraining from performing this operation with the help of pliers - the fact is that the landing pad for the cap breaks very easily, and even a slight compressive force can cause irreparable damage to it, the elimination of which will cost much more than purchasing a tool with a collet clamp.

7. After removing the glands, it is worth checking the rod and its guide at the same time. The motivation for these actions is the same as when checking the camshaft - taking the opportunity, it is worth squeezing the maximum benefit out of the repair.

8. Now that all the previous steps have been completed, you can install new valve stem seals. To do this, you need to remove the springs from them and insert the seals into the mandrel, after dropping oil on the stem.

10. The next stage is a sequence of actions that is the reverse of the one used in the analysis: all elements are installed and dried. Having done these operations the required number of times, the replacement of valve stem seals can be considered complete. It remains only to install all the elements in their places and adjust each system.

Video: replacing valve stem seals

Outcome

Replacing valve stem seals without removing the head can be done independently without any problems. It is only important to carefully monitor your actions and follow the correct sequence, but the quality work done is worth it - the engine with updated oil seals will function normally without causing its owner the slightest inconvenience.

The internal combustion engine works as a single complex mechanism. The effective interaction of the gas distribution and crank mechanisms and with the engine lubrication system is largely provided by valve stem seals. The driver not only needs to be familiar with the functions of the parts, but also to correctly diagnose wear and the need to replace oil seals.

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.

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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.

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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 impact, the cap is exposed 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 appear again 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.

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

1. oil leaks through leaks in gaskets, seals, as well as cracks in the engine crankcase, cylinder block, oil pressure sensor, etc.
2. oil seal wear
3. wear of the cylinder-piston group
4. 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 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 sort 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:

1. wear of engine parts and the ingress of wear products into the oil
2. 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 saves, thereby, 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.

Modern high-tech engines are poorly represented without a good lubrication system. But it is also necessary that the oil does not get into the cylinders.

What is a valve seal?

Due to such loads, the material from which the softest part is made becomes harder. Then the working edges of the part are erased. In this case, the valve stem seals will have to be replaced, the engine can also be flushed or preventive maintenance carried out.

However, one should not think that oil seals need to be changed every year. Modern manufacturers have already established a culture of production of these parts. Replacement is necessary every 100,000 km. But there are motors where replacement needs to be done more often.

What are the signs of wear on old valve stem seals? Here they can be seen even from the outside. Wear can be recognized by the bluish smoke from it. It can appear for a while only when the engine is started or when the engine is braked.

On a part such as valve stem seals, signs of wear in the form of smoke are not the only factor. The second sign is an increased “appetite” for oil. In this case, leakage of the lubricating fluid may not be observed at all. Speaking approximately, the consumption will increase to 1 liter of oil per 1000 km. Also, another sign is salting and oiling of the electrodes on the candles.

How to replace valve stem seals?

Many advise to carry out this operation in certified service stations, since the work requires disassembling the motor. You can carry out this operation without removing the cylinder head, you just have to stock up on the right amount of patience.

Set of tools

You will need some tools to get the job done. Usually required which is used when repairing the motor. We will need pliers and a special tool that will compress the valve spring. Tweezers will be needed in order to get the crackers. In addition to all this, you will need a mandrel, with which the seals will be pressed in. You also need a hammer and a rod of tin solder. The dimensions of the rod should be no more than 8 cm in diameter.

We carry out a replacement

Removing the valve stem seals involves the following steps. First you need to dismantle the cylinder head cover. Then turn the crankshaft. It is necessary to rotate until the mark on the camshaft sprocket aligns with the same mark on the bearing housing. Then remove together with the camshaft. Now you can fix the sprocket and chain. Disconnect wires from spark plugs and remove spark plugs.

At the next stage, we press the spring well and remove the valve drive lever. We derive from under the locking plate and remove the spring. Unscrew the adjusting screw. In place of the screw, you need to screw in a tool that can compress the valve spring. We insert our rod into the hole that was formed by removing the candle. This is required to keep the valve closed. Now let's release the crackers. To do this, it is usually necessary to compress the valve spring and tighten the cracker bolt. We remove the parts, remove the tool.

Now you can see the seals. If you do not know how to change valve stem seals, then you should use a collet clamp. This allows you to remove the seals with the help of light blows of the striker. Do not use screwdrivers, pliers, or any other similar tools to press out. This way you can cut the bushing.

The new part must be carefully put on the valve (and at the same time try not to damage its extreme part). The inner surfaces must be lubricated with oil. This will move the gland along the valve to the guide sleeve. Now it remains to lightly knock and finally press the gland.

After successful pressing, it's time to reassemble everything in reverse order. So you learned how to change valve stem seals.

How to choose oil seals?

Today there are practically no problems with spare parts. However, it is not necessary to exclude the situation when you have to trust not on the spare parts recommended by the manufacturer, but on those that are in stores.

If we talk about the choice of oil seals, then their main purpose is a seal for the valve stems, as well as valve bushings. These seals are supposed to protect the combustion chambers from oil. When oil seals are visible, signs of wear, it's time to take care of acquiring new ones.

You know how these elements are arranged. As the use of these parts shows, it is this solution that allows you to get good results. So, protection is maintained even when the valve stem suddenly warps.

New models of caps made of fluoro rubber or acrylate rubber are used on modern engines. However, no one ever said that they cannot be used on older machines.

If new signs of wear are installed on the old engine, they will appear much later than the deadline, and the motor itself will greatly benefit from such a move. This is the best solution if the cap fits the valve in terms of fitting dimensions.

It is also important to consider the profile of the inside of the stuffing box. For example, Japanese engines have caps that have a protrusion on the inside. There is a groove on the guide bush in this place. You should not experiment and put such parts on smooth bushings.

The long life of the caps will be ensured by the installation of new seals on new engines. If you can put new models of caps on an old motor and nothing will happen, then if you put an old oil seal model on a new ICE model, then anything can happen. The whole point here is not even what valve stem seals are according to design features, but the fact that new power plants operate in extremely harsh conditions. Old models of oil seals simply cannot withstand such loads. Therefore, their purchase is meaningless.

So, we found out which valve stem seals have signs of wear.