Engine valves operate under very difficult conditions. From above, the camshaft constantly acts on them, creating a lot of friction. And from below they are in an environment of high temperature exhaust gases. The camshaft, perhaps more than other parts of the engine, is lubricated with oil, as a result, it also gets on the valves, through which it flows down to the combustion chamber. If you do not prevent this process, the following will happen. The oil will mix with the air/fuel mixture in the cylinders and burn. This will lead to the formation of soot on the walls of the combustion chamber, on the pistons and piston rings - coking. The wear of the engine will increase and the characteristics of its operation and the quality of the combustible mixture will deteriorate. But the biggest problem is that soot forms on the valve seat and its head (on top of the flat part, the so-called “skirt”). The valve stops closing. Such a malfunction is a serious malfunction of the engine, which in a short time causes it to become inoperative.
Where are the oil seals
To prevent oil from entering the combustion chamber, valve stem seals (they are also valve stem seals) are installed on the valves. Confusing valve stem seals with oil scraper rings will only work in the name. How to find out, oil seals or rings? The caps are small rubber seals, and the rings are large metal thin formations that fit perfectly into the grooves of the pistons (crank mechanism). While the valve stem seals are located where the valves and guide bushings are located, between them (and this is already a gas distribution mechanism).
The valve stem oil seal is essentially a consumable in a car, but replacing such an element is equivalent to an overhaul of the engine, since it is impossible to change it without disassembling the internal combustion engine.
How many valve stem seals are in the engine? There are exactly as many of them in the engine as there are valves. That is, if it is an eight-valve internal combustion engine, then there are eight caps, respectively. As the valve moves to open and close the inlet/outlet, the cap removes excess oil from the stem (the narrow long part of the valve) so that the seating surfaces (that is, the part of the valve that interacts with the chamber) remain dry. Oil seals are made of rubber, which wears out quickly under the influence of an aggressive environment.
Signs of wear on valve stem seals
Like any consumable, the stuffing box has its own regulated use time. The resource of valve stem seals is 100,000 km. But as practice shows, oil seals become unusable before the regulated time. This is evidenced by the appearance of the following problems:
- the formation of soot on spark plugs,
- decrease in engine oil level,
- the appearance of blue smoke from the exhaust pipe when you press the gas pedal hard.
Location of valve stem seals
The most optimal solution is to install valve stem seals recommended by the manufacturer of this vehicle.
Such symptoms on a car give reason to think about replacing valve stem seals. Of course, it is better to do this in specialized car services. The price of replacing valve stem seals will fluctuate around 4-8 thousand rubles. How much do oil seals cost? Relatively inexpensive, about 500 rubles each. Now you can calculate how much it costs to replace valve stem seals. You can do the operation yourself. But note that the seals are easily deformed if not handled properly.
The first thing to do is to select the desired valve stem seals. Acrylate rubber is a more modern material than fluoroelastomer. The size of the valve stem seals can be calculated by measuring the diameter of the existing valve - this is for the inside. As for the oil seal models (the external size can also be attributed here), new ones can be installed on the old internal combustion engine, but not the best option on the new outdated ones.
Replacing valve stem seals with your own hands
For work you will need: a set of keys, a valve cracker, pliers for oil seals, a mandrel. It is most convenient to change the oil seals on the dismantled cylinder head. It is possible to remove the valve stem seals without removing the head. To do this, it will be necessary to set the top dead center for each piston when removing the seals from the valves. Otherwise, the valves have every chance to fall into the cylinder, even if you hold them, besides, when installing new caps without a stop, it will be extremely inconvenient.
Oil seal replacement procedure
So, how to change oil seals? The TDC is set or the cylinder head is removed. For the job, it is best to use a special tool to replace valve stem seals, but we will also look at how to remove valve stem seals without a puller. With the help of a cracker, the valve plate and spring are removed. Next, the oil seal is dismantled with special pliers for valve stem seals (some use pliers as a do-it-yourself valve stem seal remover, but you should take into account the risk of damage to the valve stem when using a non-specialized tool). A new oil seal is hammered with a special mandrel for valve stem seals (the mandrel can be replaced with a metal tube of a suitable diameter, but it is highly undesirable). For easier movement, the stem and the inner surface of the rubber element can be lubricated with engine oil. The blows should be gentle and accurate, since this part is fragile, subject to deformation. A dull sound indicates the installation of the valve stem seal in the seat. The same is done with the rest of the valves. After the new valve stem seals are installed, the return mechanism is dried back, the cylinder head is assembled, and other attachments are returned to their place. Operation completed.
Finally
After replacing valve stem seals
To increase the life of the oil seals, special additives for valve stem seals are used. Some of them act on the rubber part, softening it, others are aimed at sealing the resulting gaps. If the use of additives to restore valve stem seals still has its effect, then restoring valve stem seals removed from the engine does not make sense at all, since their service life will be short-lived, which means that in the near future you will have to spend money on replacing them again, which is completely unprofitable.
If after replacing the valve stem seals the problem could not be resolved, this means that the replacement was not done correctly (rarely) or the malfunction was different (often).
A common question from car owners: “Why does the car smoke after replacing valve stem seals?”. Most likely, it was not the caps that needed to be replaced, but the oil scraper rings already mentioned above (they have similar functions).
How to check valve stem seals? Some motorists check what exactly is out of order, caps or rings, like this: if smoke comes out of the exhaust pipe for 1-2 minutes, then these are caps, and if it doesn’t disappear completely, then these are rings.
It is not worth neglecting this operation, or postponing it for later. Indeed, behind the failure of small rubber seals there are large malfunctions of larger components of the internal combustion engine, up to a complete stop of the “car heart”.
Of course, lubrication is necessary for the normal operation of the engine and its components. Interestingly, oil getting into the combustion chamber itself can lead to a major overhaul of the entire internal combustion engine. But its presence on the walls just contributes to the smooth and uninterrupted operation of the entire car. Therefore, when the valves move, oil is removed from the stem by special protective elements - valve stem seals. About them and will be discussed today.
What are they needed for?
The main function of this part is to close the valve, which eliminates the possibility of oil penetrating inside. The valve stem seals always fit snugly against the valve surface, but still a few milliliters of lubricant penetrate through them. This is normal as the part should not run dry. But an excessive amount of oil already negatively affects the operation of the valve.
What are oil seals made of?
By its design, this part is with a rigid steel base. That is, the main component of the valve stem seals is rubber, since the serviceability and service life of the entire mechanism depends on the degree of its wear. The steel base can last forever, so it doesn't matter as much as its second component. As for the rubber itself, there are also some nuances here. If the cap was made of acrylate or recycled rubber, you can be sure that such a part will last a very long time. If the composition of the rubber includes other components, they can be very short. Therefore, it is better not to purchase such parts.
By the way, few people know, but today's valve stem seals are significantly different from their "ancestors". The first mechanisms had only rubber in their composition. Due to the lack of a base, these parts very quickly lost their elasticity and strength.
When are valve stem seals replaced?
VAZ 2109, like all other domestic cars, has similar symptoms if this part is leaking. The main sign of the loss of rubber properties will be increased. Also, you may observe blue or bluish smoke from the exhaust pipe (but this may also indicate. However, if you do not observe such symptoms, do not think that the condition of the caps is perfect. As a rule, manufacturers recommend changing this part every 20 thousand kilometers.Therefore, even if you do not have it, when you reach this mileage, be sure to replace this mechanism.This work is not so difficult to contact a service center for help.You can do everything yourself.Besides, the cost at the service station is 5 thousand rubles.
Finally, a little advice. If you do the replacement yourself, be sure, in addition to new caps, purchase a valve cracker puller. It can be found in absolutely any auto shop.
Every driver of a passenger car with an internal combustion engine should be able to distinguish signs of wear on valve stem seals, since otherwise the development and hardening of valve seals is fraught with a number of consequences. If the problem is identified in time, then without any problems you can buy a puller for cracking and replace rubber-metal parts even without removing the head.
How valve seals work
Oil seals, as they are called in the common people, are installed directly on the valve stems, they are a combination of a rubber cage and a steel bushing, designed to increase the rigidity of the structure. When the valve opens, the cap covers it, preventing oil from flowing into the cylinder. Of course, a certain part of the lubricant still gets under the seal, but this is the norm - there is a natural lubrication of the assembly. Over time, the elasticity of the part decreases, it shrinks, and there is an increase in the volume of leaking liquid. As a result, the oil "leaves", forcing you to top up to the norm more and more often.
Signs of wear on valve stem seals: how much oil the 1.8 engine takes
The first and foremost symptom of hardened, worn valve seals is overuse of engine oil. True, for some engines, the regulations allow noticeable deviations from the generally accepted norm of 200-300 ml per 1000 kilometers. So, 1.8 turbocharged engines installed on models of the Volkswagen AG auto concern (Volkswagen, Audi, Skoda, Seat) legally require topping up with lubricant up to 500-700 ml for every thousand kilometers. A similar situation develops around PSA Peugeot Citroën engines developed jointly with BMW (also installed on Mini models) - passport data speaks of a “norm” of 1000 ml of engine oil, which must be topped up in the engine every 1000 km.
Things like this highlight the importance of knowing "your" oil consumption. If the power unit between service operations consumes significantly more than the recommended values, then this is a serious reason to think about replacing the valve stem seals.
The second sign of oil leaving the cylinders due to the loss of their condition by the caps is bluish-gray smoke from the exhaust pipe, which can be clearly seen in the first minutes of engine operation and then when shifting gears, while pressing the accelerator pedal. Also eloquent evidence of the above problem is oil deposits on the threaded part of the spark plug. When the pressure in the combustion chamber rises, the mixture supersaturated with oil is partially squeezed out through microscopic gaps. For example, through the thread of a candle, where the gap is no more than 0.3 mm. Under the influence of high temperature, gasoline from the mixture evaporates, leaving behind a fair "reserve" of lubricant. Indirectly indicates the death of the caps and dark soot on the electrodes.
Exactly the same soot appears on the cylinder walls. And if you ignore the problem, then one day, due to plaque, the valve will simply burn.
Video tips for checking for oil fat
How to understand that you need to replace the caps, and not the engine piston system
It is very easy to confuse signs of drying out of valve seals and the development of a cylinder-piston group. In both cases, the problem matures after 200,000 km, often occurs on used cars that were bought without proper diagnostics. Moreover, zhor oil, blue smoke are characteristic of both diseases. That's just hardened valve stem seals do not affect the compression rate, which usually drops when the piston rings, the walls of the pistons themselves and the cylinders are worn. If the car consumes too much oil (from 1 liter per 1000 km), but the compression in the cylinders is normal, then 90 out of 100 are caps.
An additional check is carried out on a running engine with an unscrewed oil filler cap: an engine requiring CPG repair should have smoke from the neck, while worn caps do not cause this.
The price of a cracker puller Toyota, Volkswagen, Audi and the principle of its operation
An integral attribute of replacing valve stem seals on any engine, be it a Lexus or a VAZ, is the so-called cracker. This is a branded or universal (suitable for engines of various brands) tool for clamping valve springs, without which it is not possible to carry out repairs. The principle of operation of the cracker remover is quite simple: the cracker is attached to the engine body with reference points, with the help of mechanical pressure on the plate, the valve return spring is clamped, which allows you to dismantle the crackers.
It should also be noted that universal pullers are often not so multi-tasking - some designs are suitable for motors with an ONV, ONC, HV layout, others are designed specifically for servicing Opel SOHC engines, etc. You should clarify this point before buying an instrument.
Dryer price:
- for overhead valve engines - from 3500 rubles;
- for OHV, OHC, CHV engines - from 2000 rubles;
- a comprehensive set of tools for cracking down on engines of Toyota Camry, Volkswagen Golf, Mitsubishi Lancer, etc. - 20,000 rubles.
A cracker, as in the photo, is an essential attribute of replacing valve stem seals on any engine
Change without removing the head: the cost of a repair kit Ford, Mazda, Nissan
In the official service, experts usually insist on the option of replacing caps, which involves removing the cylinder head. So it is much easier to dismantle / install oil seals, and everything spent on fuss with Cylinder head time is paid by the client. Thus, a decent amount of money accumulates. But if you do not reach the removal of the “head”, then you will need less nerves, time, you will not have to spend money on laying cylinder head and new bolts. When accessing a cracker (it is not necessary to buy - you can, for example, temporarily borrow from a friend), the matter remains small. It is necessary to purchase a set of branded or non-original valve stem seals.
The cost of the original repair kit (valve seals):
- Toyota Camry 2.4 - 1300 rubles;
- Ford Focus 1.8 - 1500 rubles;
- Volkswagen Golf 1.6 - 1800 rubles;
- Nissan Qashqai 2.0 - 1500 rubles;
- BMW X3 2.5i - 2200 rubles;
- Mazda 6 1.8 - 1600 rubles.
Replacing MSC with Mitsubishi Lancer IX 1.6
Consider the step-by-step process of replacing valve seals on the ninth generation Mitsubishi Lancer 1.6 without removing the cylinder head.
- The ignition coils are dismantled, after which the candles are unscrewed.
- After unscrewing the six bolts, the valve cover is removed
The hoses are disconnected. - To prevent the hydraulic lifters from falling out, they can be fixed with wire or plastic clamps.
- It is necessary to unscrew 13 bolts securing the rocker arm axles. The axles are removed as an assembly without turning over (to avoid oil leakage from the compensators).
- So that the crackers do not fall into the pan, the engine holes are clogged with foam rubber, clean rags.
- Using marks on the pulley and head, TDC is set in the first and fourth cylinders.
- The biscuit remover is attached with one part to the valve head body, the second part rests against the plate, which allows you to release and remove the biscuits with tweezers.
- After removing the plate with the spring, access to the cap appears.
- The dismantling of the cap itself should ideally be done using a special removable device. But in the absence of such, you can adapt to work with pliers. However, in the absence of delicacy, it is easy to damage the valve guide.
- Before swapping the old and new caps, it does not hurt to check the valve itself for play.
- The new cap, lubricated with oil, is pressed with a suitable mandrel - you can use a 10 mm wrench.
- The spring and plate are returned to their place, with the help of tweezers and a puller, crackers are put back.
- The replacement of the MSC in the remaining two cylinders is carried out after turning the pulley along the marks and setting the TDC.
- It is highly desirable to tighten the rocker axle bolts with a torque wrench in compliance with the values recommended by the automaker (50 Nm).
Features of replacing caps on a 16-valve VAZ Priora
To gain access to the caps on the Prior, you will first have to unscrew the candles from the wells, dismantle the ignition coils, and also remove the throttle assembly. After that, it will be possible to unscrew the valve cover bolts in order to remove the rocker arms and actually replace the MSC with a puller. In general, the layout is the same as in the case of Lancer: TDC is set in the cylinders, crackers and springs are removed, new seals are installed, and reassembly is in progress. As a rule, the whole complex of works takes from the performer from 8 to 12 hours.
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September 24, 2017
In the design of any engine, both a domestic car and a foreign car, there are valve stem seals (valve seals). They are always involved when the machine is running, and therefore wear out very quickly. Increasing their service life is a headache for engineers working at automobile plants, but timely diagnosis of signs of wear on valve stem seals, as well as their replacement, is already the task of motorists. You can successfully deal with it only in one case, when these very signs are known to you, and if not, then this article will help you.
HOW SCREW CAPS WORK AND WHEN THEY COUNT Worn out
As you know, the valve in the engine is located in two different cavities. One of them implies the presence of engine oil in it, the other, on the contrary, must be isolated from it. In this case, the valve during its operation is in constant motion.
WHAT DO YOU NEED SCREW CAPS
They are made of special elastic rubber, but this rubber tends to age, harden, dry out and collapse over time, as a result, the caps no longer cope with their task and begin to need to be replaced. The car owner can determine this moment by special signs.
Worn oil seals
MAJOR SIGNS OF WEAR ON SCREW CAPS
- Increased oil consumption - if engine oil is consumed in your car more than it should be, then somewhere it is used in vain, as an option - it enters the combustion chamber due to worn valve seals.
- Oil soot on spark plugs is a consequence of the fact that oil enters the cylinders.
- when the car warms up, the engine heats up - the smoke disappears. Such a phenomenon is a clear sign of a cracked cap, which, heating up to a certain temperature, becomes wider and again begins to successfully cope with the functions assigned to it.
However, be extremely careful, these signs may indicate not only worn valve stem seals, but also other problems with the engine! Therefore, at the time of diagnosis, do not forget to pay attention to:
- mileage - as a rule, oil seals need to be replaced every 70-80 thousand km. run;
- compression - if it is reduced, but you did not find any leaks or problems with the valves and / or rings on the pistons, then the problem is definitely in the caps. They should be replaced.
CONSEQUENCES OF DRIVING WITH Worn-out oil caps
If you missed the moment of failure of the valve seals, then most likely it will lead to the following consequences:
- increased oil consumption, which, firstly, will not have the best effect on your budget, and secondly, will provoke periodic oil starvation, leading to increased wear of parts and the need for premature engine overhaul;
- oiliness and eventually failure of spark plugs;
- valve burnout - soot will form wherever there is oil, including on the walls of the cylinders, which over time will interfere with the closing of the valves and lead to their burnout.
To prevent all this from happening, carry out a timely replacement as soon as you notice the first signs of wear on the valve stem seals.
REPLACING THE SCREW CAPS: TIPS
We will not consider the procedure for replacing valve stem seals now, this is the topic of a separate article, but in the end we will name the main recommendations that will save you from mistakes. There are only 3 of them:
- to crack the valves, always use a special tool - a cracker, so you will be less likely to break or lose something;
- when changing caps, cover all holes on the engine with a rag or foam rubber, they will protect open cavities from dirt, and you from losing crackers;
- Be sure to lubricate the new cap with oil before installing.
And remember, if you do not have enough experience and knowledge in replacing valve seals, having noticed signs of wear, do not experiment, but give your car into the hands of professionals, they will quickly replace the failed parts with new ones and take a little in this case. Depending on the car and the service station, the costs will range from 7 to 20 thousand rubles.
Insufficient closing of the valves leads to the appearance of varnish deposits in the cylinder head and on the piston group.
Criteria indicating wear of oil seals:
- regular appearance of soot on spark plugs;
- excessive consumption of engine oil;
- lack of stable idle speed;
- with a sharp increase in speed - copious emission of gray smoke.
Maintenance includes regular oil, air, oil and fuel filter changes. Valve seals are designed for vehicle operation up to 100,000 km. In fact, it is necessary to carry out the replacement earlier than the specified resource.
The device of valve stem seals (valve seals)
The oil seal has the shape of a cylinder with a truncated cone. For tight contact with the surface of the valve guide, a polymer ring with an expander spring is provided. A plastic (or rubber) ring removes excess oil when the valve stem moves, and the spring allows it to be tightly fixed on the stem.
For a long time, a rubber ring was used in the design of the stuffing box. Rubber and fluoroplastic options have appeared recently. This is due to the fact that rubber tans faster and loses its properties. Manufacture of the ring using modern polymers extends the life of the stuffing box.
Purpose of oil scraper caps
Long-term uninterrupted operation of the internal combustion engine is ensured by high-quality lubrication of rubbing parts. The oil distribution mechanism provides oil supply in a small volume. Camshafts in the cylinder head and piston group - need constant lubrication. The shaft rotates and a cloud of oil forms around it. The amount of lubrication is regulated by oil scraper caps.
Carbon deposits on the valve surface lead to incomplete closure and gap formation. In the combustion chamber, the combustible mixture ignites, and excess oil settles in the form of varnish deposits. When the valve is lowered down, the stem seal prevents excess oil from entering. Protects the piston group from plaque that occurs during the combustion of oil and fuel mixture. Oil seals are considered consumable items, as they need to be replaced periodically.
The location of the oil scraper caps in the engine
The head with camshafts and valves is mounted on the cylinder block. The valve stem moves through the guide bush. The thermal gap between the leg and the sleeve is closed with caps. The oil seal is positioned so that oil from the head does not enter the combustion chamber. The camshaft journals receive oil under pressure, and the rest of the nodes - due to splashing. Having removed the engine block head and camshafts, you can see the location of the seals in the valve seats.
Signs of worn valve stem seals
You can find out about the need for replacement without disassembling the engine. Valve stem seals have the following signs of wear:
- excessive oil consumption;
- bluish smoke;
- soot on spark plugs.
Worn seals increase oil consumption. This also happens when the piston group is "coked", but there is a visual difference. Visible oil streaks on the breather pipe. Blue-colored smoke exhaust is a sign that oil is entering the combustion chamber. "Tripling" of the engine and soot on the spark plugs are justified by the flow of oil through the stem seal. The car needs diagnostics and replacement of oil seals.
The service life of oil scrapers does not depend on the price and manufacturer. For budget and "premium" auto-resource is designed for mileage up to 100,000 km.
Oil seal replacement procedure
- Disconnecting the air filter, removing the cover and air ducts. Branch pipes and technical openings are closed with plugs. Remove spark plugs and cylinder head bolts.
- The piston in the first cylinder is set to top dead center. Removing the lock washer and star. The valve locknuts are released, and the adjusters are unscrewed to the stop.
- Crackers and springs are removed. The puller removes the seals. The bushings are lubricated with oil, put on the rod and installed with a hammer and a frame.
- Assemble components and parts in reverse order. After, the rest of the caps are changed in a similar algorithm in the order of cylinders 4 - 2 - 3.
Servicing each cylinder requires a 180 degree crankshaft rotation.
Self-replacement will require a special tool. The main specific device is the "raskuharivatel" of the valves. You will need it to replace the valve seal. Devices and materials:
- sets of socket and cap keys;
- head extension;
- rod and hammer;
- Collet clamp;
- pressing frame;
- tweezers;
- head gasket;
- set of new caps;
- sealant.
During the work, it is possible to replace the gaskets under the block and cylinder head. New oil seals are selected for a specific engine model.
Procedure for replacing valve stem seals
Consider how valve stem seals are replaced on an 8-valve engine without removing the head:
- Remove the fuel pump and air filter.
- We turn off the battery power and dismantle the ignition distributor.
- We unscrew the top cover of the block, disconnect the toothed pulley and mass.
- Evenly unscrew and remove the fastening nuts on the camshaft and bearings.
- We dismantle the shafts and seals.
- By turning the crankshaft, we raise the piston to TDC on the serviced cylinder.
- We insert a soft tin rod under the valve through the hole for the candle.
- We remove the springs with a special device and remove the plates. We replace the seals by pressing the old ones from the bushing and installing new ones.
- We assemble in the reverse order. We proceed to a consistent similar replacement on the remaining cylinders.
Before installation in the frame, the caps are lubricated with oil. They are pressed into the plate carefully, without sharp strong blows.
Gaskets and seals are installed under the bolt heads. Sort small items to avoid losing them.
After replacing all the valve seals, assemble the head by placing it on the sealant and a new gasket. Tighten the nuts with a certain torque, according to the instruction manual for this engine.
For different engines, valve seal kits differ in design. Installation is carried out according to technical recommendations for a specific car model. When carrying out work yourself, adhere to the accuracy:
- coincidence of the diameters of the sleeve belt and the valve stem;
- the length of the seats of the guide sleeve and cap;
- installation on oil with reliable fixation (without the slightest backlash);
- selection of a set of caps for a specific engine model.
A high class of accuracy in the manufacture of parts allows you to increase the density of the connection and the complete coincidence of dimensions.
On sale there are additives for the restoration of oil seals. Their principle of operation is to soften the hardened rubber of the o-ring. Manufacturers differ in the quality of additives. There are different effects on rubber: no effect or excessive softening, which leads to excessive consumption of oil.
