DIY plunger pump repair

In detail: do-it-yourself plunger pump repair from a real master for the site my.housecope.com.

Almost all high pressure hydraulic systems are equipped with plunger pumps. High pressure plunger pumps have all the qualities that are taken into account when choosing pumps for such systems, such as: reliability, ease of implementation of the product and efficiency.

The high pressure plunger pump serves as a mechanism or drive for other mechanisms in special machines. Hydraulic pumps are widespread and are responsible for the normal and harmonious operation of the vehicle. The plunger pump is used in a wide variety of fields of activity.

The plunger, translated from English, means to dive or submerge, therefore, these devices are used for hydraulic machines.

P80 bentonite plunger pump

A plunger pump is a simple-acting positive displacement pump, which is equipped with a plunger-shaped working body.

In turn, the plunger is a part of various types of pumps associated with hydraulics and multistage compressors for gas.

In terms of design, specifics of operation and structure, a plunger-type pump is similar to a piston unit. The presence of a special piston, in the form of a plunger, is the main distinguishing feature of plunger pistons from piston ones. Due to the creation of high pressure in the system plunger-type pumps are not used in everyday life.

The pressure units have found their main application in the chemical and oil refining industries. The use of such devices allows mixing with high precision the components of solutions in the proportions required for the process, which is very convenient in production processes. Differences are inherent in the design features of these pumps, and therefore the plunger devices are divided into:

Video (click to play).

Due to the specific nature of the work, the plunger pump unit is manufactured as a wear-resistant, sealed, durable plunger that ensures continuous and reliable operation.

These units are high-performance devices with high efficiency, which is up to 90%. According to the properties of design features, plunger devices are classified into types:

vertical;
horizontal;
manual;
auto;
multi-plunger;
multi-cylinder;
with sealed cylinders.

Plunger pump HAWK 610003

Plunger pumps have a number of advantages over analogues that clearly stand out:

the lubrication system is thoroughly worked out and has good access for the consumer;
due to the design, it is possible to change the parameters and characteristics for the customer;
have clear and simple control of the device, as well as easy to install;
it is possible to increase or decrease the working pressure in the hydraulic system by changing the number of piston groups.

In the chemical industry, for the manufacture of chemicals that do not chemically react with metals.
In the chemical industry for well drilling and transportation and subsequent processing of petroleum products.
In power engineering for the manufacture of electric drives for steam generators.
For hydraulically driven equipment in mechanical engineering.
In public utilities to carry out repair work related to hydraulic communications.
In reverse osmosis machines for the food industry.
High pressure plunger pump for water is applicable for car washes.

The design of a plunger pump is simple and consists of valves and a piping system.The spring assists in the work of the plunger valve by creating a systematic discharge. There is a chance of skipping when working with high pressure. In order to avoid such nuances, the high pressure plunger pump for water has a complete tightness of the unit components.

High pressure plunger water pumps and devices in this category are designed on the principle of a reciprocating nature, provided by a camshaft.

During this movement, the plunger (aka piston) is set in motion by a roller pusher. By its design, the plunger moves to the right side, which causes a decrease in the working pressure, which gradually becomes less than the liquid pressure in the suction pipe.

Internal structure of the plunger metering pump

The suction valve opens due to the pressure difference, after which the working chamber is filled with liquid. At the next revolution of the shaft, the plunger moves to the left and the pressure in the chamber becomes greater than in the discharge line. In this regard, the discharge valve opens and the liquid is squeezed out of the chamber into the pressure pipeline. This entire cycle is repeated constantly during the entire operation time of the unit.

Some plunger pumps may differ in design from each other, but their principle of operation will remain unchanged.

For example, a boost pump in a diesel engine does not have pressure valves. This important role for pumping and the pressure is generated by the nozzle valves.

In axial radial pumps, these functions are performed by rotating units in the working chambers. Axial-radial installations are designed so that liquid is pumped when these blocks rotate. The absence of valves increases the cost of such installations, but this allows them to increase their reliability and use in aviation.
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Science and industry are developing and based on practice, scientific research, analysis of the design features of pumps, etc., small-sized unified three-plunger pumps have been designed and introduced into production.

The triple plunger pump is a fourth generation NPG type pump. These devices differ from previous generations in the diameter of the main element (plunger), the hydraulic box and the properties of the valve assemblies of the system. Such systems for increased pressure usually have a basic configuration:

pressure sensors, alarms and pressure gauges;
safety valve;
shut-off or stop valves;
filter for water purification;
gear oil pump;
liquid cooling system;
safety valve.

If the place where will be installed the plunger assembly will be stationary, it will be advisable to choose a flat surface for it. This solution allows for routine inspections, emergency repairs and equipment maintenance. Surfaces must be rigid and prepared for high vibrations from the installation.

High pressure plunger pump

In order to ensure a continuous and normal supply to the pump for water, it is necessary to use high-quality flexible hoses, which avoids unnecessary stress on all the nodal parts of the equipment. It is not recommended to connect rigid piping to the drain outlet.

The drive shaft and the crankshaft must be one after the other in a straight line, without making sure of this, do not start the hydraulic system into operation. If this condition is not met, the transfer belt will not perform all its functionality and the entire mechanism may fail. The pump shaft should rotate freely, easily by hand. It is also necessary to correctly select the rotation of the pump electric drive in order to avoid back pressure.
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Most often, they undertake to make a do-it-yourself high-pressure manual pump for car washes. For this, plunger pumps are used, for which the drive is used from an electric motor (electric pump). The engine power must meet the required parameters and the rated power must be at least 75% of the desired value. Often used as a pump pump.

If the permeability of cars at the car wash is not high, you can use an electric motor designed for a voltage of 220V. For safe operation and to reduce the discrepancy in the coincidence of the motor and pump shafts when connecting them, it is recommended to choose soft couplings. The container for the liquid is selected on the basis of a sufficient volume of water.

It must be connected to a water make-up source and equipped with a filter element to prevent unwanted foreign matter from entering the pump system.

The filter element can be made of fine mesh stainless steel. An important piece of equipment is a capacity regulator or a non-return valve. It prevents overloading the system and prevents back pressure from building back into the water supply.

Homemade high pressure pump

All this equipment will require a sturdy frame to install. For its convenient movement, wheels of the desired diameter are installed, a solid stop for stability and a handle for easy fixation. For reliability and high performance, it is necessary to use reinforced rubber hoses that are designed for high pressure.

The main element of such equipment is the nozzle gun. It is not advisable to make it with your own hands due to technical difficulties. It is better to purchase this part in the store. It must be remembered that all work carried out on high pressure pumps must be carried out using clean liquid. Foreign bodies entering the system will damage most of the equipment.

Hydraulic systems have found applications in many industries. Hydraulic pumps are important in performing their functions, ensuring the efficient operation of the system. They are of different types and purposes, which explains the differences in the principles of the mechanisms.

In addition to the main function of supplying the required fluid under a certain pressure, the hydraulic pump can serve as a drive for other devices. One of the most common is the so-called plunger pump. It is a single-action device that increases the efficiency of work, the main part of which is designed as a plunger.

Plunger refers to a reciprocating piston in a hydraulic system. Its appearance is distinguished by its cylindrical shape, characterized by a length that significantly exceeds the diameter.

Plungers are used in hydraulic machines, pumps and diesel engines. The seal, an integral part of the displacer, is located on the cylinder itself, as a result of which, when the latter moves, it moves along the surface of the plunger. This detail distinguishes the plunger from a conventional piston and explains the superiority of the former in high pressure applications. The main indicator of the efficiency of the plunger is the volume of liquid displaced by it, it depends on the length of its stroke. The displacer is regulated by the latter factor. Such mechanisms are usually used for pumping large volumes of liquid media.
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In order to understand the principle of operation of this device, first you need to explain what a plunger pump is. This is a unit, the use of which is due to the need to supply a certain liquid (mixture) under the influence of high pressure.The reciprocating movement of the plunger, directed to the right, causes a decrease in pressure in the chamber where the displacer is located, which leads to the opening of the suction valve and further filling of the chamber with the required liquid.

The chamber in which the plunger is located is a closed space, if necessary, connected to the pipeline by means of valves. There are only three types of them: suction, discharge and safety.

The next step in the operation of the plunger is to move it to the left, as a result of which the pressure in the special chamber rises, thereby opening the discharge valve through which water or other mixtures enter the pipeline. The principle of operation lies in the fact that in both the first and second cases there is a difference in pressure, due to which the system works smoothly and without disturbances. During operation, energy is transferred to the fluid to overcome inertia, resistance and static height in the pipeline. The most popular are triple plunger pumps. The increased interest in them is due to their advantages and the almost complete absence of disadvantages.

The scheme of the plunger pair

You can make a piston pump for pumping water in your own garden with your own hands. To do this, you will need two valves that will not allow liquid to spontaneously flow out, the projectile, which is the main part of the mechanism, and the body. The body can be made from a pipe. Pipe length not less than 60 cm, pipe diameter not less than 8 mm. Your own piston pump will not be expensive, but in terms of technical characteristics it will be inferior to industrial models.
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Axial plunger pumps can be classified according to three main criteria:

manual;
mechanical, more efficient to use than a manual water pump.

single;
double, characterized by the presence of several working chambers;
differential, related to double-acting pumps and having two chambers. As a result, it pumps liquid more evenly.

By type of pumped liquid:

High pressure plunger pumps have found their way into many applications. These include:

Axial-plunger pump device

Building;
Metallurgy;
Oil industry;
Chemical industry;
Water purification;
Food industry;
Water supply (water pump);
Energy;
Mechanical engineering (internal combustion engines);
Car wash.

It should be noted that, depending on the application, various configuration options for the plunger pump are possible. For example, those models used in the oil industry do not include discharge valves. Their functions are performed by valves in the injectors. This circumstance improves the reliability of the plunger.
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The high pressure axial plunger pump has many advantages. These include:

Rhythmic operation of the mechanism, which is ensured by pressure and discharge valves on both sides of the special chamber;
Simplicity, as a result of which it is not difficult to make a high-pressure plunger pump with your own hands and carry out its installation;
Power;
Long-term operation;
Modular design, thanks to which, if necessary, you can order the manufacture of a plunger pump with individual characteristics, for example, for a car wash;
Compliance with international standards;
A wide range of pumped products, with different temperatures and consistencies.
The compactness of the axial plunger units saves the working surface;
The ability to adjust the speed, this keeps the situation under control;
The ability to change the working volume of the device;
High performance.

In addition to the advantages, the use of axial plunger structures also has disadvantages.They arise during intensive work and are expressed in the appearance of pulsations and vibrations. Their negative effect can be prevented by attaching additional devices to the high-pressure pump with your own hands. They can be working plungers. For example, a triple plunger pump is vibration-free.

Plunger pump HAWK 610003

Incorrect operation of the device threatens with frequent breakdowns, which will be difficult to fix. Therefore, if you do not have such experience, you should not install or repair plunger pumps yourself. Time will be wasted and quality may suffer.
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The service life of the device depends on the correct use of the device, therefore it is necessary to know all the nuances of installation and use of axial plunger pumps.

Do not operate the unit without lubrication, as this will impair its performance.
The device can only rotate forward, otherwise observe the oil level prescribed by the instructions in this regard.
The unit must be installed on a horizontal surface, without slopes and unevenness.
In humid hot climates, the pump must not be used without ventilation. Otherwise, it will fail ahead of time.
Freezing or damage to the pump during cold seasons must be prevented. It is strictly forbidden to start the device with frozen water inside.

In any case, before starting work with the plunger pump, it is imperative to study the instructions and it is not recommended to neglect this rule.
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Piston pumps and axial plunger pumps are quite similar, but there are still slight differences in their design. First of all, this concerns the shape of the piston, and secondly, its location. The plunger does not touch the walls of the working cab, which cannot be said about the piston in other models. Plunger units are quite possible to operate in the field, it became possible due to their size. Such high pressure water pumps are much more popular than others.Axial plunger pumps and electric pumps are used everywhere. They work effectively in any industry and in everyday life. Manufacturers are constantly improving quality by modernizing technology, applying innovations and making economical models.The high pressure fuel pump is an essential component in every diesel engine. Because of this mechanism, the fuel becomes not just a liquid, but a fuel-air mixture. A part such as a plunger pair also acts on the operation of the pump. She is responsible for fuel supply and distribution.There are two main parts in the design of this element - the plunger and the sleeve.The plunger consists of a small cylindrical piston. When the pump is running, the plunger moves inside the sleeve. Performing up and down movements, the plunger sucks in fuel, and then it is pumped alternately into the nozzles of the working cylinders, where it ignites under high pressure in an atomized state. The plunger pair of the high pressure fuel pump has several holes on the sleeve through which diesel fuel is supplied for subsequent injection.In other words, the main purpose of the plunger pair is to accurately measure the fuel, so that it can then be fed into the engine cylinders. Also, this element helps the pump to supply fuel at the right moment with the right pressure. In order for everything to be carried out without interruptions, it is necessary that the plunger pair meet all the requirements. Therefore, the plunger pair, the price of which is not so small, must be produced on high-tech equipment, it is unrealistic to make it at home.Plunger pair of injection pump - a complex element, it must be operated with caution and the necessary requirements must be constantly observed. In order for the device to work smoothly and efficiently, only high quality fuel should be used.Since the fuel quality at our filling stations leaves much to be desired, the restoration of plunger pairs is a very popular service.Low-quality fuel contains a large amount of chemical elements, which significantly reduces the durability of the plunger pair. The most negative effect is produced by water, which enters the fuel as condensate. If there is a lot of water between the sleeve and the plunger, then the lubricating film breaks its integrity and then the part works without lubrication. This can deform the part so much that restoring the plunger pairs simply will not help. All that remains is to buy a plunger pair in the store and try to refuel only with high-quality fuel.There are several signs that a part is defective. One of them is the refusal of the motor to start, especially when the motor is warmed up. It is possible to find out whether the plunger pair of the injection pump is working normally while the engine is running. We must pay attention to the quality of his work. If the plunger pair is faulty, then the motor loses power, and it works with uncharacteristic sounds. In addition, the engine may run intermittently and become unstable. If at least one symptom was noticed, then it is necessary to make a diagnosis.It should be noted that special equipment is used for diagnostics. Therefore, it is very difficult to say at home whether the plunger pair is faulty or not. In the service station, professionals can say for sure about the malfunction and the method of solving this is adjustment or complete replacement. During the repair, special equipment is needed to restore the tightness of the sleeve and plunger.Now it should be told how to replace the plunger pair. First you need to go to the store, pick up and buy a plunger pair that will fit a particular engine. It is necessary to disassemble everything that is removed around the fuel pump. This is necessary in order to remove the old plunger pair without problems and nothing gets in the way. Then you need to remove the front cover of the engine, unscrew the nut securing the drive gear, and then unscrew all the tubes and remove the fuel pump. All parts that are in the dirt must be cleaned at the same time. Only then can you begin to disassemble the fuel pump, unscrew the plunger pair itself, but only do it with extreme caution and in a specially prepared place with a set of necessary tools.It is necessary to carefully drain the fuel from it, dismantle the old plunger pair, check the condition of the remaining parts, namely the cam washer, rollers, the booster pump, etc. Then you can reassemble everything in the reverse order, after thoroughly washing the plunger pair with diesel fuel from preservation before installation.To adjust the amount of fuel that is injected, there is a special cut-off lip on the plunger. When the movement of the plunger goes up, it first closes the outlet hole, and through this edge the hole opens slightly. The cutting of this edge is made with a spiral, so that when the plunger is turned, the time before the cut-off changes. In order for the plunger to rotate and make translational movements, it rests on the cam washer and engages with its pin. When the washer rotates, it also rotates the plunger, and the cams run into the rollers and push it. The plunger is adjusted with shims of different thickness. The most important thing is not to forget that the price of a plunger pair is quite high, it is a very fragile and complex part, so it must be handled very carefully.The operation of a diesel engine is four strokes, during which a combustible mixture of fuel and air is formed. Ignition occurs not due to a spark, but due to high pressure, therefore, the compression ratio of diesel engines is always increased.Cummins Inc.Is one of the world's leading manufacturers of diesel engines and generators. The engines of this company are very different: power varies from 30 to 3600 horsepower, and engine sizes from 1.5 to 90 liters.There is no more complex and critical unit in a diesel engine than the fuel injection system, more precisely, its main part - the high pressure fuel pump. Many mating parts, high-loaded units, the presence of a precision dosing system, make the repair of the injection pump a difficult task even in service conditions. It is all the more difficult to repair the high pressure fuel pump of a diesel engine with your own hands.In automotive technology, almost everything is repaired, except, perhaps, individual oil seals and cuffs, the repair of which is impossible without special materials. The complexity of setting, diagnosing and repairing the injection pump requires the employee to have skills in working with precision mechanics.It is simply impossible to adjust according to the factory parameters, without a special diagnostic stand for the repair of the injection pump. During the diagnostic study of the injection pump, it is necessary to check:

cyclic supply of the high-pressure pump, in the entire range of revolutions of the injection pump shaft, at start-up, and after cutting off the fuel supply;

stability of the developed pressure;

uniformity of the injection pump delivery to the fuel injector.

Even having access to a diagnostic stand, and having studied the issue of repairing a high-pressure fuel pump using numerous videos, it is very difficult to qualitatively check and evaluate its work.In heavy diesel engines, plunger, in-line injection pumps are used. In maintenance and repair, such devices are more difficult, since they require special equipment for its disassembly, therefore we will not consider such high pressure fuel pumps and their repair.In a passenger diesel engine, a distribution type injection pump is almost always used. Unlike in-line pumps, in a distribution pump, the force is transmitted to the plunger using a profiled cam washer. The design of the injection pump turned out to be more compact, but it is hardly simpler to expect to carry out its repair on the knee.The most famous and affordable is the Bosh VP44 injection pump. Often, the need to repair the pump internals arises when:

poor traction and incomplete combustion of fuel even under ideal conditions - in the absence of load and a thoroughly warmed up engine;

a sudden failure and stoppage of a diesel engine under load, which is called “death on takeoff”. Usually the scanner in such cases diagnoses the code P1630 and P1651.

the appearance of a diesel fuel leak in the area of the gland seal of the central shaft of the injection pump.

Therefore, we will restrict ourselves to the issue of repairing the injection pump with our own hands by replacing the seals and eliminating the scoring of the working surfaces of the parts.Before disassembling the pump drive shaft seal, try to move it radially. If play is felt with your hands, it is possible that the reason for the leakage of fuel is the wear of the working surface of the shaft or requires repair of the bearing.A large number of split planes and mating surfaces of parts required the use of a large number of seals and glands. As a rule, they are made of quality material and last long enough until they are damaged during repair or maintenance. In this case, standard repair kits are used for DIY repair of Bosch injection pumps.It is quite easy to replace the seal on the shaft position sensor and on the automatic injection timing during repairs. For a better fit, you can drip a few drops of spindle or engine oil onto new rings and rubber bands. Image - DIY plunger pump repair

For preventive repair of a Bosch injection pump with your own hands, you will need to disassemble the pump in approximately the following order:

remove the metering valve from the end of the injection pump. To do this, unscrew the four screws of the pressure plate, carefully release the cable of the injection advance valve. By removing the three screws securing the metering valve, you can carefully remove it from the seat;

by unscrewing the fastener on the top cover, you can remove the control board and gain access to the electronics;
we set the position of the shaft, as shown in the photo, remove the camera and get access to the insides of the injection pump;

after dismantling the bearing using a special puller, we get the opportunity to study the potential culprit for the poor performance of the injection pump - the piston of the injection advance unit. There is often surface wear and edge scuffing on the part. You can try to make repairs by polishing the surface, replacing the whole part is much more expensive.

After the repair, the assembly is carried out in the reverse order with the washing of the parts with diesel fuel.

Often, in addition to scoring, on the surface of the pistons there is another reason why the injection pump does not develop the required pressure. This can be due to debris, films or wax build-up on the filter screen inside the pump. There is a mesh on the side of the inlet pipe. Rinsing the channels is a troublesome and ineffective business, it is easier to remove the mesh and blow it with compressed air.

Torn pieces of debris can jam the plunger piston or even break or break the pump drive shaft. Therefore, cleaning should be done very carefully to avoid contamination of the internal cavities of the pump.

Among the many reasons for the failure of the electronic "liver" of the injection pump, the most common is the breakage or burnout of the contacts of the control board and the failure of power transistors. If the knowledge and skills of working with electronic devices allow to carry out a "continuity" of the transistor performance and repair, it is worth trying to identify the cause and replace the culprit with a serviceable element.

To check the condition of the "culprit", you need to carefully open the black cover, which is tightly seated on the rubber seal with screws. It should be removed carefully so as not to damage the seal itself.

The reason for the failure of not only the transistor, but also the entire board could be air trapped in the cavity due to poor performance of the drainage system or the check valve. Often, they try to eliminate the airing by spinning up with a starter, hoping to pump diesel fuel into the high-pressure fuel pump in this way. At this moment, the transistor is open and loaded as much as possible, which leads to intense heating. In an air environment with poor heat dissipation, it will inevitably burn out. In some German cars there is a protection that prevents an attempt to start the engine in the absence of fuel in the highway. For this, a fuel sensor in the tank is used.

Failure of the transistor can be established by "dialing" a tester or by its appearance. The best option for repairing such a malfunction would be to replace the entire control board. Perhaps it is more expensive than soldering, but it will give guaranteed quality and stable operation of the injection pump after repair. As a last resort, give the board and the transistor for soldering to electronics specialists.

When installing and reassembling after repairs, check the tightness of all fasteners.

If during the audit you did not make rash and unreasonable replacements of parts, the assembled pump should work with approximately the same parameters as before. Bosch EPS-815 stand is used as a standard for testing and adjusting injection pump after overhaul.

The video shows how to raise the plunger pressure in a Bosch VE injection pump:

Any owner is pleased with a good technique, proven in practice and has justified itself more than once. The newest technology always surprises and alarms with its characteristics, surpassing the characteristics of very old technology, which is still in use by many.Some masters always try to acquire for their business the equipment of well-known companies of a certain brand and persuade their friends and acquaintances to do this, others are guided by the price and buy only what is expensive for themselves, and the manufacturer is not interested in them. Image - DIY plunger pump repair

Where is the guarantee that any equipment we purchase fully complies with the quality certificate under which it is sold? Where is the longevity promised by the manufacturer if we operate their equipment in our conditions, and moreover, ‘feed’ it with our fuel and according to our recipes?

Nowadays, there are a lot of equipment that can be sold at different prices in different retail outlets. No one will tell you where and who assembled the same petrol cutter or chainsaw that you purchased. A well-known brand, and the assembly can be carried out in a nearby garage for accessories, perhaps even in a makeshift way.

A big problem that causes various types of breakdowns in most budget chainsaws is their poor-quality assembly, inadequate components, or even a negligent attitude towards the entire assembly process by unprepared assemblers.

Many owners of chainsaws noticed an oil stain on the place where their chainsaw was resting or stored. Oil under the saw does not start leaking immediately. And with poor assembly, more precisely, with poor-quality assembly of the chainsaw, an oil stain may appear immediately after refueling.

Except for mechanical damage to the oil tank and oil supply system, there are not many reasons for oil leakage.

Loose connection of the supply oil line with the inlet of the oil pump of the chainsaw and poor tightness between the hole of the oil tank and the line.
Technical compliance with the dimensions of the plunger and the discharge chamber of the oil pump.
Loose connection between the supply line and the oil pump outlet to the saw chain lubrication point.
Violation of the tightness of the plunger chamber of the oil pump.

I will dwell on the last option in more detail, since it is in the event of a loss of tightness of the plunger chamber that oil leaks, and in saw structures, where the oil tank is located above the oil pump, oil flows out after a couple of days of idle time of the chainsaw.

Eliminate oil leakage from the chainsaw oil pump it is possible and all this happens quickly if someone is good at a screwdriver and wrenches. If your chainsaw has passed a small working resource, then the problem is solved simply.

As I mentioned earlier, the guarantee of the trouble-free operation of your chainsaw is ensured not only by observing optimal operating conditions for it and using the manufacturer's recommendations, it is also ensured by the appropriate quality of component parts, but most of all by the most high-quality assembly.

Let the part be manufactured on high-precision equipment, but when it is installed incorrectly or does not fix it with the appropriate effort, then the promised warranty from the manufacturer will disappoint you.

Like plunger type oil pump, installed on most models of budget chainsaws, is simple in design. The principle of its operation does not differ from the operation of some plunger oil pumps of other categories of chainsaws.

I will briefly describe in my own words the principle of operation of a plunger-type oil pump of similar models, so that it would be a little clearer when familiarizing myself with my method of correcting oil leaks through the oil pump of a chainsaw.

The oil pump on chainsaws is valveless and is mounted on the crankcase of the chainsaw from the side of the saw chain drive. The role of the valve in these pumps is performed by a segmented cutout at the end of the plunger. The plunger is driven from the clutch by a pair of drive from the worm hub. It turns out that the pump plunger rotates in the same direction and at the same time it itself closes the inlet and outlet channels of the oil line in a cycle, combining the function of the valves.

When the segmented cutout at the end of the plunger opens the inlet of the oil supply line, the plunger moves slightly out of the pump chamber, thereby picking up oil from the line through the open hole.

As the plunger rotates further, the inlet channel of the pump's oil chamber closes and the opening of the discharge channel opens. At the same time, the plunger moves inward and pumps the trapped oil into the oil channel to the lubrication point by the piston.

With one rotation around its axis, the plunger makes one reciprocating movement along its axis, the magnitude of the stroke of which is regulated by a screw with an eccentric transversely installed at the end of the plunger shaft. Some people like to call it a cam.

The eccentric rests against the central protrusion on the end of the plunger shaft, and the greater the deflection angle of the adjusting screw, the further the eccentric located on it will push the plunger shaft away from itself. In the largest eccentric deviation, oil cannot be pumped out by the pump. The saw chain is not lubricated.

In addition to the central protrusion on the end of the plunger shaft, there is an annular protrusion with a profiled surface that determines the magnitude of the plunger stroke along its axis. That is, the level of oil capture and injection.

A metal spring is mounted on the plunger shaft, which, resting with one side against the oil pump housing, constantly pushes the plunger shaft towards the adjusting screw.

The profiled surface of the annular ledge is in contact with the cylindrical body of the adjusting screw. At the point of their contact, an interface is formed, which, when the plunger shaft rotates, sets a value that limits the movement of the plunger along its axis and affects the process of capturing and pumping oil by the plunger.

The oil pump will operate at maximum output provided that the adjusting screw eccentric does not come into contact with the center boss on the plunger shaft end. As the adjusting screw rotates, the eccentric will move closer to the shoulder and push the plunger shaft away from it. In this case, the amount of oil supplied by the pump for lubrication will depend on the position of the eccentric relative to the protrusion on the plunger shaft, and in this example, the amount of oil supplied by the pump is controlled.

It often happens that oil is not supplied to the saw chain, even when the adjusting screw is in the maximum oil supply. There are not many reasons:

after disassembling the oil pump, the adjusting screw is set at 180 ° relative to its original position.

It is enough to reposition the adjusting screw or leave it that way. Then the screw positions for maximum and minimum oil supply () are reversed.

The profiled surface of the annular ledge is worn out and no longer looks like a profiled one, but flat. The plunger does not move along its axis.

We change the oil pump or form a profile and sharpen the central protrusion at the end of the plunger shaft. In this case, the volume of the pump working chamber will slightly increase.

When adjusting the profile and the protrusion, it is necessary to maintain the same maximum dimensions in height relative to each other, so that when the adjusting screw is in the minimum mode, the plunger will pump oil a little. In the new pump, the central protrusion at the end of the plunger shaft is about 0.3 ... 0.6 mm higher than the level of the annular profile, and in the position of the adjusting screw with a minimum oil supply, the oil pump does not work.

Wear on the inner surface of the pump plunger chamber and the outer surface of the plunger.

This, usually, manifests itself with a previous defect or with what I will describe next. We change the oil pump or sort out the sets according to the size of the used one.

Violation of the tightness of the working plunger chamber.

A little oil can be supplied to the lubrication point, but there is a lot of grease on the saw casing on the chain drive side.

The last example speaks of the plunger collar, which in many cases is installed in the opposite direction, with the collar outward. Some masters argued that this is a cuff that captures oil into the pump chamber. But how does this cuff behave when inflated? Pass oil through itself?

Some people choose rubber rings instead of him, but believe me, this is not easy and very caring for the inexperienced. This method is good, but the tightness of the O-ring must be considered. If the ring sits tightly in place, then it will be necessary to replace the plunger spring, and there will also be increased wear of the mating unit of the adjusting screw and the plunger shaft. The wear of the plastic hub of the pump drive worm pair will also be added.

The ease of movement of the plunger is maintained by the use of a cuff, which does not interfere with the reverse stroke at the moment the plunger is seized by oil and maintains a sufficient tightness of the working chamber when pumping oil.

At the first opportunity, at the chainsaws that come to me, I always disassemble the oil pump in order to be completely sure of the condition of the plunger and its cuff. In the case when the cuff is installed with the collar outward, then I reinstall it on the contrary, with the collar towards the working plunger chamber of the oil pump.

Video (click to play).

This is my method, which always justifies itself, provided that no one interfered with the design of the oil pump and the oil was supplied to the pump through the oil filter.

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