In order for a car engine to work properly for as long as possible, and also to avoid increased oil and gasoline consumption, it requires timely maintenance or repair. Such mandatory procedures also include valve stem seals. Next we will talk in detail about valve seals and look at what these parts are. In this article we will answer questions about what signs you can use to determine the need to replace the valve stem seals and how to change the valve stem seals yourself.
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General information about valve stem seals
Oil seals (oil seals) are part of the oil distribution mechanism in the engine. The presence of oil is the most important condition for work. But it doesn’t have to be everywhere. For example, during its rotation it is always in an oil mist. But there should be no lubricant in the combustion chambers. There is only a fuel-air mixture, which burns. If you add oil to it, combustion will worsen, which will affect the increase in gasoline consumption.
Removing coke deposits and carbon deposits in the engine: available methods. Self-flushing of the engine without opening, mechanical cleaning of the engine.
Engine valves operate under very difficult conditions. The camshaft continuously acts on them from above, creating a lot of friction. And from below they are in an environment of high temperature exhaust gases. The camshaft, perhaps more than other engine parts, is lubricated with oil, as a result it also gets onto the valves, through which it flows down to the combustion chamber. If this process is not prevented, the following will happen. The oil will mix with the fuel-air mixture in the cylinders and burn. This will lead to the formation of carbon deposits on the walls of the combustion chamber and on the pistons and piston rings - coking. Engine wear will increase and its performance and the quality of the combustible mixture will deteriorate. But the biggest problem is that carbon deposits form 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 renders it inoperative.
Where are the valve stem seals located?
To prevent oil from entering the combustion chamber, oil seals (also known as valve stem seals) are installed on the valves. The confusion between valve stem seals and oil scraper rings is only in name. How to find out, valve stem seals or rings? The caps are small rubber seals, and the rings are large thin metal structures that fit perfectly into the grooves of the pistons (crank mechanism). While the valve stem seals are located where the valves and guide bushings are located, between them (and this is the gas distribution mechanism).
The valve stem seal is essentially a consumable in a car, but replacing such an element is equivalent to a major overhaul of the engine, since it is impossible to change it without disassembling the internal combustion engine.
How many valve stem seals are there in an engine? There are exactly the same number 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, opening and closing the inlet/outlet port, the cap removes excess oil from the stem (the narrow, long part of the valve) so that the operating surfaces (that is, the part of the valve that interacts with the chamber) remain dry. Valve seals are made of rubber, which wears out quickly when exposed to aggressive environments.
Signs of wear on valve stem seals
Like any consumable, the oil seal has its own regulated time of use. The service life of the valve stem seals is 100,000 km. But as practice shows, oil seals become unusable before the regulated time. This is evidenced by the following problems:
- formation of carbon deposits on the spark plugs,
- reducing the engine oil level,
- the appearance of bluish smoke from the exhaust pipe when the gas pedal is pressed hard.
Location of valve stem seals
The best solution is to install valve stem seals recommended by the manufacturer of the vehicle.
Such symptoms on a car give reason to think about replacing the valve stem seals. It is, of course, better to do this in specialized car services. The cost of replacing valve stem seals will range from 4 to 8 thousand rubles. How much do the oil seals themselves cost? Relatively inexpensive, about 500 rubles each. Now you can calculate how much it costs to replace valve stem seals. You can perform the operation yourself. But please note that oil seals are easily deformed if not handled correctly.
The first thing you need to do is select the right valve stem seals. Acrylate rubber is a more modern material than fluorine rubber. The size of the valve stem seals can be calculated by measuring the diameter of the existing valve - this is for the internal part. As for the models of oil seals (the external size can also be included here), new ones can be installed on an old internal combustion engine, but outdated ones are not the best option on a new one.
Replacing valve stem seals with your own hands
To work you will need: set of keys, valve depressurizer, pliers for valve stem seals, mandrel. It is most convenient to change the valve stem seals on a dismantled cylinder head. It is possible to remove the valve stem seals without removing the head. To do this, you will need to set the top dead center for each piston when removing the seals from the valves. Otherwise, the valves have every chance of falling into the cylinder, even if you hold them, and it will be extremely inconvenient when installing new caps without a stop.
Procedure for replacing valve stem seals
So, how to change valve stem seals? The TDC is installed or the cylinder head is removed. For the job, it is best to use a special tool for replacing valve stem seals, but we will also look at how to remove valve stem seals without a puller. Using a desiccant, the valve plate and spring are removed. Next, the oil seal is dismantled using 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 special mandrel for valve stem seals is used to hammer in the new oil seal (the mandrel can be replaced with a metal tube of a suitable diameter, but it is highly undesirable). For easier movement, the rod and the inner surface of the rubber element can be lubricated with engine oil. The blows should be gentle and precise, since this part is fragile and subject to deformation. A dull sound indicates that the valve stem seal is installed in the seat. The same is done with the remaining 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 place. The operation is completed.
Finally
After replacing the valve stem seals
To increase the service life of oil seals, special additives are used for valve stem seals. Some of them act on the rubber part, softening it, others are aimed at sealing the resulting gaps. If the use of additives for restoring valve stem seals still has its effect, then restoring valve stem seals removed from the engine makes no sense at all, since their service life will be short-lived, which means that in the near future you will have to spend money again on the procedure for replacing them, which is absolutely unprofitable.
If after replacing the oil seals the problem could not be resolved, this means that the replacement was carried out incorrectly (rarely) or the fault was elsewhere (often).
A common question from car owners is: “Why does the car smoke after replacing the valve stem seals?” Most likely, it was not the caps that needed to be replaced, but the oil scraper rings already mentioned above (their functions are similar).
How to check valve stem seals? Some car enthusiasts check what exactly has failed, the caps or rings, like this: if smoke comes out of the exhaust pipe for 1-2 minutes, then it’s the caps, and if it doesn’t disappear completely, then it’s the rings.
You should not neglect this operation or postpone it until later. After all, behind the failure of small rubber seals there are major malfunctions of larger components of the internal combustion engine, up to the complete stop of the “heart of the car.”
The combustion chamber of a car must be protected from the entry of foreign substances and elements into it. The valve stem seals are responsible for this, the task of which is to prevent excess oil, chips and other “garbage” from entering the combustion chamber during the movement of the car’s valve stems. If the valve stem seals no longer cope with their tasks, they must be urgently replaced to avoid carbon deposits on the engine elements, as well as increased oil consumption. In this article, we will look at what signs indicate wear of the valve stem seals, why they wear out, and how to replace them without removing the cylinder head.
Why are valve stem seals needed?
Engine operation involves non-stop operation of the elements of the vehicle's gas distribution mechanism. To reduce their wear due to friction, oil is supplied to the timing gear, which should not end up in the combustion valve, otherwise the stable operation of the engine will be disrupted. When the valves operate, the oil seals take on the task of removing excess oil and act as an obstacle, preventing oil from entering the combustion chamber.
The valve stem seals are designed quite simply, and we can name 3 main components of which they consist:
- Base. A sleeve made of steel, which is the frame of the cap and gives it strength;
- Spring. Necessary to create the tightest possible fit between the edges of the cap and the stem;
- Cap. The main element of the part, made of rubber or polyethylene resin (older models). Its task is to remove excess lubricant from the valve stem.
It is worth noting that over the last decade, valve stem seals have changed a lot in terms of the materials used. Since their failure can lead to big problems, manufacturers strive to use the most durable and wear-resistant materials that are resistant to aggressive environments.
Service life of valve stem seals
It is easy to guess that valve stem seals need to be changed from time to time. The valve performs more than 1000 strokes per minute, and on each valve, the valve stem seals must remove excess oil to prevent it from entering the combustion chamber. It should also be taken into account that the temperature in the operating area of the valve stem seals is high, and the environment itself is aggressive: oil and exhaust gases.
Due to the influence of a host of factors, valve stem seals begin to deteriorate over time - the rubber of the cap cracks, peels off, and loses elasticity. Over time, the spring begins to press the cap less tightly against the walls, which is why oil begins to enter the combustion chamber.
On average, the service life of good quality valve stem seals is 100,000 kilometers. If the car has been idle for several years, it is recommended to replace the valve stem seals before you start using it, since during inactivity they have time to dry out greatly.
Signs of wear on valve stem seals
If you recognize the wear of oil seals at an early stage and replace them in time, you will be able to avoid serious engine problems. The primary signs of oil seal failure are as follows:
- Thick blue or white smoke comes out of the car exhaust;
- Oil consumption increases significantly;
- Carbon deposits appear on the spark plugs.
When the signs of wear on the valve stem seals described above occur, you need to urgently inspect them, as well as check the gas distribution mechanism and valves. If there are signs of severe wear on the valve stem seals, they need to be replaced, otherwise:
- Engine power will begin to decrease;
- The car will stall at idle, or the speed will begin to “float”;
- Compression in the engine will decrease;
- Carbon deposits will form on the pistons and cylinders, and the valves will no longer provide a tight seal due to poor closure.
Carbon deposits on engine components are a direct path to a quick overhaul. Timely replacement of valve stem seals with new ones will help avoid this.
How to replace valve stem seals without removing the cylinder head
If the problem with wear of the valve stem seals was detected in a timely manner by the driver, he can replace them without removing the cylinder head. In a situation where the solution to the problem has been delayed, it will be necessary to dismantle the parts to remove carbon deposits from the pistons and valves.
Depending on the car model and engine, the process of replacing valve stem seals will vary. But we can distinguish several main stages common to all machines:
If there is a possibility that the valve stem seals have been faulty for a long time, you will need to remove the cylinder head and carry out a full replacement, including cleaning the engine elements from carbon deposits.
The internal combustion engine operates as a single complex mechanism. The effective interaction of the gas distribution and crank mechanisms and with the engine lubrication system is largely ensured by valve stem seals. The driver must not only be familiar with the functions of the parts, but also correctly diagnose wear and the need to replace oil seals.
What are valve stem seals used 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 that are placed on the piston. On the other hand, in the gas distribution mechanism the contacting surfaces are lubricated.
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A kind of oil suspension is created under the cylinder head cover. The valve stem seals are located at the boundary of the cylinder and the cavity above it. Their task is to prevent oil mist and oil from the valve stem from entering the cylinder combustion chamber.
It is easy 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 heats up to high temperatures.
How many are there and where are they located on the engine?
Based on the purpose and work performed, it is easy to determine where the oil seals are located. If we consider the engine assembly, the cap is placed 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 won’t have to rack your brains about how many valve stem seals there 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.
Causes of wear
Along with constant mechanical stress, the cap experiences the aggressive action of heated oil and impurities in it. Don't forget about the hot exhaust gases during the exhaust stroke.
Over time, natural rubber becomes rougher, the walls of the sleeve crack and wear out. Despite the fact that the technical maintenance regulations have not determined the exact interval for replacing the caps, if the corresponding symptoms appear, you should not delay replacing with new parts.
How to determine the need for replacement
Among the main criteria that directly indicate the need to replace valve stem seals are:
Oiling of spark plug electrodes. Oil has the ability to leak 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 per thousand.
The appearance of bluish smoke during the exhaust. Some of the oil has time to burn during the compression stroke.
Sometimes a dilemma arises as to what causes blue smoke from the exhaust pipe. By mistake, wear of parts of the cylinder-piston group is often cited as such a cause. To finally decide whether an engine overhaul or oil seal replacement is needed, just check the compression. The normal value of this indicator allows you to confidently point to the caps.
By the way, the problem of increased oil consumption can be resolved in the short term by using special products. A special additive for softening oil seals will restore the functionality of the parts for a couple of thousand kilometers. The additive takes effect 500-700 km after addition. Do not delay repairs; most likely, similar symptoms of engine wear will appear again soon.
How to choose everything you need for work
When contacting a service center, changing the oil seals is not difficult. However, this approach will mean for the car owner the option of performing work with removing the cylinder head, which implies replacing the gasket and mounting bolts. Yes, and the time investment here is large. This option means a significant overpayment.
The easiest option is to do the work yourself. To do this, you should prepare a tool for replacing oil seals and buy 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 engine, 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 costs less, ranging from 800 to 1200 rubles, respectively.
When choosing analogues, do not be lazy to check the parts correspondence to the VIN number, or ask for advice from the store manager.
Selecting a puller
To successfully replace the valve stem seals without removing the head, you will need to buy a special tool. As a last resort, you might be able to borrow such a set from your neighbor in the garage.
To do the job you will need a tool, better known as a desiccant. When choosing, you should pay attention to the equipment indicating its suitability for use with a specific 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 using mechanical pressure. After removing the crackers, access to the valve stem seals opens.
DIY removal and installation procedure
At the initial stage of the work, the car is de-energized, the ignition coil is turned off and the spark plugs 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:
The valve cover and all hoses are removed. The rocker arm bolts are loosened.
We remove the rocker arms. At the same time, make sure that the crackers do not fly away when removed from the axle. Do not remove the rocker arms from the axle or turn them over to prevent oil from leaking from the hydraulic compensator.
Install the puller and compress the spring. As a result, two crackers are released, which need to be removed (it is convenient to use tweezers).
We remove the valve plate and gain access to the valve spring and washer.
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.
The new cap is placed on the lubricated valve axis using a mandrel. The spring and valve plate and crackers are returned in reverse order.
When tightening the rocker arm bolts, use a torque wrench. Often the tightening torque is set at 50 Nm.
If it is necessary to change the oil seals in cylinders 2 and 3, the pistons must also be moved to their extreme position.
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If the engine consumes an increased amount of oil and smokes when you press the gas pedal, then you should prepare to replace the valve stem seals. Let's talk about when they should be changed and what signs of wear are there.
Signs of wear
Let us explain why caps are needed. Their purpose is to prevent excess engine oil from passing through. They should fit snugly against the valve and allow only the small amount of oil through that is needed for lubrication. Made from special rubber that is not afraid of high temperatures.Over time, the valve stem seal begins to deteriorate, rubber ages and loses elasticity and peels off from the base. It starts leaking oil. Consequently, engine oil consumption increases. As a rule, on domestic cars the replacement interval is 80,000 kilometers. For modern engines, this period can be increased by 2-3 times due to the use of modern materials and good motor oil. These conditions are valid unless there is engine overheating or oil starvation.
Does your car engine have an increased appetite for oil? Does the engine consume more than 1 liter per 1000 kilometers? Is there blue smoke coming from the exhaust pipe? These are the first signs of wear on the valve stem seals. Of course, you don’t have to think about major repairs if the dynamic characteristics have not decreased and fuel consumption has not increased.
These problems can be solved by replacing the caps and doing it yourself. You will need a garage and tools for repairs - the most necessary thing is a valve cotter remover. It can be found at an auto tool store.
Video instruction
We will not go into the procedure for replacing engine caps. Detailed operation can be found in the technical repair manual. In addition, everything is explained there clearly, thoroughly and with pictures. For example, a video showing the replacement process is the easiest way.To carry out the work, you will need a special tool - a device for “drying out” the valves. Without it, this work cannot be completed. You can find drawings on the Internet and make them yourself. It’s easier to buy a ready-made tool at an auto store.
There is a great danger of replacing the caps when trying to “de-dry” the valves. For this purpose, there is a special device, one end of which is fixedly attached, and the other presses on the plate, while compressing the valve return spring. Then you should remove the “crackers” from the valve. It is better to do this with a magnetic screwdriver or long pliers. be careful, if you lose the “cracker”, then the reassembly process will be impossible. In practice, these little “crackers” can fly out in an unknown direction, and then they are difficult to find.
Also, you need to cover all the holes on the engine with foam rubber so that “crackers” or dirt do not get there. When installing a new cap, do not forget to pre-lubricate it with engine oil.
The operation of changing worn valve stem seals can be done independently, but experience and tools are required. If you don’t have the knowledge, then it’s better not to get down to business. The price is not high, so entrust this operation to the experts.
