Repair of a power tiller by yourself
December 26, 0 reviews
Sooner or later all types of machinery need maintenance. It is not only a question of regular diagnostics and preventive measures, but also in cases when a component part comes to the end of its working life. After all, each engine has a certain motor life. If we’re talking about motor-block engines, in gasoline engines it’s about 1500 hours, and in diesel engines it’s close to 4000 hours. After serving this period, the engine parts begin to fail, and the single-axle tractor begins to need skilled intervention in his device.
It is best when it is done by professional mechanical engineers in the service center. But if you are sure you have enough skill and know how to work with your power tiller and the right tools, you can do the repair at home. All you will need to do is identify the problem in your power tiller and choose the most effective measures to fix it.
Let’s try to classify the most common problems, how you can cope with them and prolong the work of the power tiller without significant financial costs.
How to correctly install piston rings on the compressor?
Air compressor (automotive). Installing the piston rings.
Piston rings should be installed on the piston only after connecting the piston directly to the connecting rod.
If pistons that have been removed are reinstalled, they must be thoroughly cleaned, especially the piston ring grooves and oil drain holes in the piston ring groove.
Cleaning the piston groove from all kinds of carbon deposits can be done with a special tool or with a piece of old piston ring. When cleaning the piston ring grooves, be careful not to remove any metal from the piston.
Check piston lock end clearance in the cylinder and side clearance between the ring and the piston groove wall before installing the rings in the piston groove.
The piston ring should be inserted into the cylinder. In order to position the ring perpendicular to the cylinder axis, the ring must be aligned in the cylinder with the piston inverted. When installing a new piston ring in a cylinder that has not been bored, the ring must be pushed through to the depth of the piston stroke, as the upper part of the cylinder may have an oversized diameter due to wear.
Use a set of flat feelers to measure the clearance in the piston ring lock, which must meet the manufacturer’s specifications. This clearance is between 0.5 ÷ 0.15 mm, depending on piston diameter. If the clearance turns out to be less than the prescribed norm, it should be adjusted by filing the ends of the ring lock.
Vertical (axial) clearance between the end face of the ring and the piston groove:
Use a set of flat gauges to check the clearance between the groove surface and the end face of the ring. It is not necessary to install the ring on the piston for this check. The clearance should be checked all around the piston. Compare the clearance value with that given by the manufacturer. The clearance is usually 0.04 ÷ 0.08 mm. If the clearance is greater than the prescribed amount, the piston must be replaced or a thicker ring must be used
Carefully examine the compression rings and determine which is the top ring and which is the second ring. Locate the mark on the rings, which indicates which side of the ring, set towards the bottom of the piston (up).
The marks may look like: “”, “○”, “TOR”, “T”. Typically, information about the tag and how to identify the top ring can be found on the packaging of a set of piston rings.
Install the liner ring first. When installing a box liner with a coil spring expander, the spring lock must be displaced 180º from the lock of the ring.
When installing a composite liner ring, first install the spacers (expander). After checking that the expander fits correctly, install the lower lamellar ring and then the upper lamellar ring. The locks of the slat rings should be positioned at an angle of 180º in relation to each other.
Parts of the composite liner are installed by hand without using special tools.
Determine which compression ring is the lower compression ring and which side it should face towards the bottom of the piston.
Very carefully, using a special tool, install the ring.
Do not install compression piston rings by hand. To do this, use the special tool. If the ring installed by hand, it can be irreparably damaged, and there is no way to verify that the ring.
Do not open the ends of compression rings more than necessary to install the rings on the piston.
Install the upper compression ring in the same manner.
Make sure that all rings without jams and easily rotate in their grooves around the circumference and when compressed, the rings can be fully recessed into the grooves, without protruding beyond the surface of the piston.
Check again the clearance between the side face of the compression rings and the piston groove wall (vertically).
Before installing the piston and rings directly into the cylinder set the locks of all piston rings at an angle of 120º.
Piston ring locks should not be located in the middle of piston bearing surfaces, especially the main surface. Do not locate piston ring locks on the face faces of the piston pin.
Before installing the assembled connecting rod and piston assembly, once again verify that the piston ring interlocks are in the correct position.
Signs of piston ring wear
To understand whether piston rings should be changed, it is necessary to study the symptoms that directly or indirectly indicate the need for such replacement. At once we shall note, that it is not necessary to count on that sum which initially has sounded the mechanic or car-care center in the answer to a question of the customer, how many costs replacement of piston rings.
The fact is that it is often not possible to change only the piston rings and completely solve the problem, since after opening the engine, additional hidden defects are usually revealed. For this reason, it is necessary to be prepared in advance for more serious expenses for engine repair.
Impending replacement of piston rings is determined by the following signs:
- the engine loses power; ;
- in some cases, the engine is difficult to start “hot”;
- increased engine oil consumption; blue or gray smoke;
- Fuel consumption increases;
The compression index depends on the general state of the rings and the entire cylinder head, which can be used to determine the condition of the engine. Usually with the symptoms described above, cylinder compression is decreased and crankcase pressure is increased.
We also recommend reading the article on how to measure the compression in the engine. From this article you will learn about the features and available ways to measure the compression of the engine with their own hands.
Loss of power, increased fuel consumption and difficult starting are most often the main reasons that force the owner to change the piston rings or do a comprehensive repair of the internal combustion engine. Engine with defective rings does not start well, especially after idle time in cold weather. When driving under load, such an engine does not “pull”.
Piston ring defects may be caused by natural wear and tear, as well as by engine overheating. In the second case, even on a new engine the rings lose their properties and cease to perform their direct function. The most subject to overheating are box type liners.
Significant consumption of engine oil is often due to the fact that a worn oil ring does not remove oil in the proper amount from the walls of the cylinders and actively passes the lubricant through the looseness in the combustion chamber. The result is coking and fuming of the engine. Also, the unburned oil residues in the engine actively contaminate the exhaust system, rendering the filters and catalytic converters unusable. The problem is further aggravated.
For an accurate diagnosis of the condition of the cylinder head, compression measurement should be accompanied by analysis of the color and content of exhaust gases. The fact that the deterioration of piston rings can be compensated by the engine oil. In this case, the compression value may be close to the permissible value, but the oil consumption will still be increased.
Remember, operating an engine with worn rings causes the wear of the cylinder bore to progress considerably. This is why piston rings should be replaced as soon as possible after the problem has been precisely identified. This recommendation will help to avoid increasing the cost of subsequent engine repairs.
Increased fuel consumption in the case of piston ring problems occurs as a result of decreased compression and reduced power. In parallel, the driver continues to drive at the usual pace, pushing harder on the gas pedal to compensate for losses. As a result, an enriched fuel-air mixture enters the cylinders and is not completely combusted. Spark plugs often get filled with fuel in such conditions.
Another unpleasant thing is the ingress of gasoline or diesel fuel through the worn piston rings into the engine crankcase and the subsequent mixing of the fuel with the engine oil. Oil in the lubrication system liquefies, loses its protective and other useful properties, and the wear of loaded CCG and CRG details thus increases significantly.
We should add that today it is quite widespread practice to use an additive to clean the piston rings in oil or fuel. Owners also sometimes fill the cylinders with the so-called engine de-icer. This is done to clean the fouling in the combustion chamber and to try to return mobility to the piston rings to increase compression.
It is worth noting that if there are clear signs of malfunction (heavy smokiness, high oil consumption, low compression, etc.), the.д.) additive instead of replacing piston rings is either a temporary measure, or does not help to correct the situation at all.
Compression rings, wiper rings, installation
Piston rings form the seal between the cylinder wall and piston. Must provide a good seal across the entire cylinder surface over a wide temperature range. Three rings are used more often in four-stroke engines, of which two are compression rings and the bottom one is a scraper.
- Compression rings provide a tight seal between the cylinder and piston to seal the combustion chamber.
- Heat removal from the piston to the cylinder walls.
- Wiper rings remove excess oil from the cylinder walls, preventing it from entering the combustion chamber. However, it is not removed completely, but regulated, leaving the required amount of oil for the compression rings.
First compression ring
Designed exclusively to prevent the bursting of expanding gases in the combustion chamber. During the stroke cycle, the increasing pressure in the combustion chamber presses the first compression ring against the bottom of the piston groove and presses it harder against the cylinder walls, thereby providing sufficient insulation of the combustion chamber. The pressure in the groove of the ring is retained during the following stroke before it has time to release. The clearance between the ring and the groove is 0.04-0.08 mm
Protects the second ring from high combustion temperatures and reduces stress. Has the greatest heat transfer from piston to cylinder, with about 50 to 60% of the heat transfer from piston to cylinder occurring on the compression rings. Some of the gases escape, the second ring begins to fulfil its function, more on that later.
The first compression ring is made from high grade cast iron or steel that can withstand high temperatures and loads while having a low coefficient of thermal expansion. During engine operation, the temperature of the ring reaches 180-210°C and at the top dead center, where there is practically no lubrication due to friction, an even higher temperature is reached. Often a special coating is applied to the outside of the ring to reduce friction. This can be plasma cladding of molybdenum, ceramic metal, or ceramics. often there is a chrome coating, which has a gray matte color (electroplated) and a peculiar porous structure that allows oil retention for greater friction reduction. The remaining surfaces are black by phosphating. Coating provides anti-friction and anti-corrosion properties.
Compression rings are not perfectly round, but have a complex arc shape in the free state and a sufficiently large end gap. When the ring takes its place in the piston and is inserted into the cylinder, it will provide uniform downforce at every point of the circumference.
Second compression ring
works in more favorable conditions and performs the function of an additional seal. Due to its special shape, it helps to remove the excess oil, leaving only an oil film on the surface of the cylinder. Average Ring Temperature 150. 170 °C in Run Mode. The clearance between the ring and the piston groove is slightly less than the first one.03-0.06mm. Made of cast iron and very brittle. The variety of ring shapes results in certain functions. such as load distribution in the groove, reduction of friction on the piston skirt by aquaplaning with oil, removal of excess oil.
The bevel on the inside of the ring determines in which direction the ring will bend. If the bevel is at the bottom, the ring will evert with the outer surface downwards after heating, as shown in the picture. And accordingly if the bevel is at the top, then the working surface of the ring will be everted upwards.
A scraper ring is located underneath the compression rings and acts to remove excess oil from the cylinder walls.
Large amount of oil that penetrates through the compression rings into the combustion chamber, affecting engine performance. During operation, the combustion oil is deposited on the valve walls, combustion chamber, spark plugs, piston bottom. Heavy soot build-up heats up, increasing the probability of detonation. Exhaust valves are subjected to an increased temperature load.
The thin film of oil left by the wear rings reduces friction on the rings, increasing their durability. Wiper rings are not pressed by the working pressure of gas to the plane of the groove in the piston and the cylinder walls, so they have special axial and radial expansions.
Two types of rings can be distinguished by their construction: boxed and dialed, both can have different reamers.
Wipers scrape excess oil from the cylinder walls as the piston moves down, guiding it through drainage holes in the piston back into the crankcase. An oil wedge in front of the ring helps lubricate the piston skirt effectively. Cylinder walls are roughened, so called honing, to trap the finest oil for the compression rings.
common are wear rings consisting of two thin steel plates (often with different coatings to reduce friction) and a tangential expander that expands axially and radially at the same time. Used in modern engines.
Quick installation of a piston ring by hand, performed without breaking it, although it confirms the dexterity of the mechanic, but it often leads to damage to the ring at the time of installation.
- Never install the ring on the piston in the way shown in the illustration. A deformed ring no longer lies flat in the groove, does not rotate in it, wears unevenly and no longer provides a proper seal. However, the situation is even worse when a molybdenum-coated ring has a peeling or damaged molybdenum layer. This damage to the sliding layer occurs during engine operation if not at the time of installation. The sliding layer flakes off, damaging the cylinder and piston where scoring occurs as a result of hot exhaust gases escaping between the piston and cylinder wall. Parts of the coating that have come loose cause damage to the piston and cylinder bore.
- Do not remove or install piston rings unless necessary. Each time the rings are removed or installed, they become deformed. Do not remove rings from pre-assembled pistons to check their dimensions, for example.
- Piston rings must be installed in the correct order: first install the intake ring, then the second compression ring, then the first compression ring.
Be sure to follow the positioning marks. “Top” means that this side of the ring must be on top and pointing towards the combustion chamber. If in doubt, or if “Top” is missing, install the ring with the lettering facing up.
Check that the rings turn freely in the ring grooves.
Check by pressing successively around the circumference whether the ring is fully recessed in the ring groove, i.e. е. the rings should not protrude beyond the edge of the piston skirt at the point of recessing. This is important, because if there is insufficient clearance to the bottom of the groove (due to the use of unsuitable rings or fouling at the bottom of the groove) the proper functioning of the rings is not guaranteed.
When installing 2-piece piston rings, always observe the correct position of the spring expander. The ends of the spring expander should always be on the opposite side of the piston ring lock.
For 3-piece rings, correct positioning of the expander spring is essential to oil removal. Even if a piston with pre-assembled rings is installed in the cylinder, be sure to check that the extension spring is properly positioned. During transport of such pistons, the spring ends are in a non-tensioned state, due to which it is possible for them to overlap. Both colored markings on the ends of the spring should be visible. If either one is not visible, the ends of the spring are overlapped and the ring will not function. All locks of the 3-piece piston liner ring (both steel plates and the expander spring) must be installed at an angle of 120° with respect to one another.
Selection and replacement of piston rings
The quality of piston rings directly affects their service life and the capabilities of your engine, so when selecting new sets of these parts, pay attention to the following points:
- Price. Cheap parts don’t last long
- Appearance and Packing. The packaging should include complete information about the manufacturer, materials, etc.д. Inside it should be a detailed instruction on how to install the parts
- The appearance of the rings themselves. The packaging must be free of even the smallest imperfections, metal bumps, etc.
Replacing piston rings is not a complicated procedure. To remove the rings, spread their edges until they come out of the groove. You can do it with a small flat screwdriver, but it is better to use a special collet tool, which will also be useful when installing new rings.
Next, clean the grooves from carbon deposits. Without this procedure, it will be difficult to put the piston back in the cylinder. Use a suitable tool for the removal of dirt or an old compression ring that is broken in two. After cleaning the grooves, check them for damage.
Before installing the new rings be sure to read the manual. it contains information on the sequence and correct positioning of the parts.
Carry out all operations carefully, remember that the strength of the lower compression and scraper rings is lower than that of the upper compression ring.
Install the lower ring first. To avoid inadvertently deforming it, check the. If a ring is marked “TOP”, it must be positioned with the marked part towards the bottom of the piston.
After installation, check the clearance between the rings and the cylinder walls. It must be up to 0.1 mm wide. If the number indicated is greater, the pistons themselves are to be replaced, possibly a cylinder needs to be bored or re-bored.
After completing the ring replacement procedure, run the engine for 3 to 5 thousand hours. km. During the running-in period be sure to warm the engine after start-up, do not run it at high RPM, avoid long idle times and driving in high gears at low speed.
Correct installation of piston rings
Sooner or later your engine will wear out and require either replacement of the piston rings or the piston as a whole.
It seems to change the piston rings. it is an ordinary task, available to anyone who is little or no more familiar with the structure and operating principles of the primitive four-stroke engine. But, unfortunately, people are afraid to spend 15 minutes of their incredibly precious time on reading the literature and shove everything in the motor on the principle (and that’s how it was). probably will work). Well, flag in your hands and go to the service as soon as possible.
Well, and for those who don’t care how their motor will run after the rebuild, you should read this article.
So, we take a piston and see 3 recesses for installing piston rings. There are no limiters on 4-stroke motors like on 2-stroke motors, for example.
There are two kinds of piston rings on 4-stroke engines. The first two, which are installed in the top two pistons, are compression. Even from the name it is clear that they are responsible for the presence of compression in your engine and must hold the gases formed at the moment of ignition by the combustion of fuel in the combustion chamber.
The next three rings are scraper rings. Here, their function is also immediately clear. They’re responsible for stripping the oil that’s covering the cylinder walls when the piston comes back down. If these rings will leak, the oil will remain on the cylinder walls, and it is fraught with the fact that the engine will start to burn oil, and, of course, there will be smoke.
How to install the primary? Yes, they are basically the same as they were at the factory, in the same order, but to avoid mistakes, we show them again.
Install the main liner first: the one with the wave-like structure. It’s the easiest ring to install, since it’s the most elastic of all.
Next, we put the top and bottom SOFT lube rings. They’re a little harder, but there shouldn’t be a problem installing them either.
Now put the piston compression rings: the thicker and “harder” ones. First install the lower, then the upper. They are a little harder to fit, because they are less elastic and harder. You will hardly be able to break them, but if you have very bad hands they will be extremely easy to bend.
The point is that the rings still need to be positioned correctly on the piston, so that the ring locks (kerf spot) do not get on top of each other. To put it simply, the kerf of the lower ring must not be located directly over the kerf of the upper ring.
The lock of the lower ring is placed in the middle over the valve cavity, for example, in the intake (you can and exhaust, there is no difference).
The lock of the upper ring is positioned strictly opposite to the lower ring. Accordingly, if the lock of the lower ring is over the cavity under the intake valve, the lock of the upper ring is over the cavity under the exhaust valve.
Now move on to the linchpin rings. These rings need to be positioned in exactly the same way so that no one locks overlap. Therefore, the upper ring is placed over the piston pin hole, on the right side.
We place the second ring (the lower one) on the opposite side, also about in the middle of the hole under the piston pin.
We put the last wavy ring in any of the four sections between the pin hole and the valve cavity.
And now to your question: what kind of nonsense is the author telling us here? And why so painstakingly set the position of all 5 rings?
Explanation. All this we have done to prevent the situation when one lock was located over the other, no gases pass through these locks (in the case of piston rings) and oil does not stay on the walls (in the case of slinger rings).
If you take into account the piston rings, it is a loss of compression and the passage of red-hot working gases to the intake rings, which are not designed for such suddenly high operating temperatures. As a result, the rings can burn out after a certain time.
Typical malfunctions and repair of a power tiller
The table lists the main breakdowns of power tillers and cultivators, and how to fix them.
- Increased wear of gears and bearings;
- Lack of lubrication in the box;
- Insufficient tightening of assembly fasteners
- Disassemble the gearbox and replace worn parts;
- Fill up transmission oil in gearbox;
- Check bolt tightening level and integrity of sealing layers, if any.
- The air filter is out of order;
- Dirty injectors or carburetor;
- Poor quality gasoline or diesel fuel.
- Insufficiently tighten the fasteners of the assembly; Replace the filter;
- Blow out nozzles; disassemble and wash carburetor, blow out nozzles, soak part in solvent and repeat cleaning;
- Drain old fuel, replace filter components, replace spark plugs, blow out injectors, or clean carburetor. Depending on the type of internal combustion engine.
- Fuel does not correspond to the current temperature regime;
- Nozzles are clogged;
- Low compression in cylinder;. Check bolt tightness
- Pour fuel of the appropriate brand;
- Blow out the nozzles;
- To restore normal compression apply the following set of measures: retorque the cylinder head nuts, clean or replace the piston rings (depending on the degree of wear), adjust the clearance.
- Insufficient cable tension;
- Dirty clutch discs.
- Tighten the cable or replace it with a new one if it has been stretched out due to prolonged use;
- Replace clutch discs and damper springs and adjust clearances at same time.
- Worn gears on one wheel
- Replace worn tire
- Wear of gears in gearbox;
- Wear of spline holes in the shafts;
- Wear of bearings and retaining rings.
- Replace unusable parts.
- Cable jamming;
- Deformation of clutch discs.
- Replace clutch discs and cable for new ones.
- Insufficient gearbox oil fill.
- Fill with new grease and check the oil grade beforehand.
- Excessive mixture in the cylinders;
- Flap closed on cold start.
- Adjust the carburetor;
- Restore the correct position of the choke.
This is a checklist for diagnosing the most common malfunctions. Requires service call for complicated problems. Routine repair of the cultivator should be carried out in April-May, before the start of gardening work. Repairs should include checking fasteners, replacing spark plugs, changing fuel and lubricants.