Why the piston is burnt out on the trimmer. How to repair the lawnmower if the engine does not start.

Causes of failure of gasoline and electric trimmers

Grass trimmer, both electric and with an internal combustion engine (ICE), is an indispensable tool in the summer and autumn period for owners of dachas and private homes. With its help weeds, small bushes and lawn can be easily removed. But, like any technique, grass trimmers fail at the most inopportune moment. To eliminate malfunctions with their own hands, the user of this equipment must first determine the cause of their appearance.

With lawn mowers and electric grass trimmers, if we do not consider breakdowns related to the boom and mowing head, malfunctions mainly occur in the area of the engine.

Breakdowns of gasoline trimmers

Typical breakdowns of the gasoline grass trimmer, which the owners of this unit are most often faced with, are as follows:

• engine failure;
• problems with the carburetor;
• malfunction of the fuel supply;
• muffler failure;
• gearbox malfunction;
• starter is broken;
• problems with the air filter;
• The breather on the gasoline tank is clogged.

Faults of electric trimmers

As the device of the electric mower is much easier than mototrimmer, the reasons for its failure are few.

It should be noted that it is better to entrust the elimination of some of them to a specialist.

Basically, the grass trimmer stops working normally in the following cases:

• Faulty electrical cable;
• A control button is defective;
• burned out motor stator winding;
• breakage of the contact connections on the motor.

Other causes

The causes of chain saw shutdown are not always surface level. If all of the above methods have not helped, there are other options for malfunction.

Such elements are subject to diagnostics:

Users who are not well versed in the device of the saw, it is not recommended to conduct an in-depth inspection on their own. Careless actions can lead to serious damage to the tool.

Causes of carburetor failure can be different:

To assess the condition of the carburetor it is recommended to show the tool in the service center. Preference is given to branded centers, the specialists of which know about the peculiarities of the unit of a particular manufacturer.

Despite its imposing appearance, a chainsaw is a fragile tool that needs to be treated properly. For proper performance it is important to supply chain saw with good quality fuel and not to let it stagnate in the tank

In order not to be left in a hopeless situation, the owner of a chainsaw should become familiar with the structure of the unit and its internal elements in detail.

Chainsaw piston group

The dimensions of the piston group are determined primarily by the diameter of the piston, which is made of heat-resistant aluminum alloy. Regardless of the model, the chainsaw cylinder consists of the cylinder, piston, piston pin and two retainers.

In order to increase compression in the working unit and, consequently, to increase power, many manufacturers install two piston rings each. Chainsaw compression rings made of special cast iron fit tightly on the cylinder, resulting in a tightly sealed combustion chamber.

Causes of chain saw piston failure

There are many reasons for the failure of the cylinder head, which are classified into two main categories: natural wear and man-made faults. The first type of failure, as the name suggests, includes physical wear and tear of the piston group’s rubbing parts. The second category is more extensive and includes:

• severe internal combustion engine overheating and consequent appearance of thermal scoring on the piston surface;
• Breakage of the lower part of the piston (skirt) due to continuous operation of the chainsaw at the utmost rpm;
• ingress of foreign particles into the combustion chamber and occurrence of mechanical damage to the cylinder head;
• breakage of the compression (piston) ring due to heavy wear or exceeding the permissible RPM of the saw;
• Inconsistency of the recommended portions of gasoline and oil in the preparation of the fuel mixture.

Specialists do not recommend to disassemble the cylinder head without a special reason. However, if the tool has significantly lost power, there was a metallic ringing in the ICE or the crankshaft does not turn when jerking the starter, you should make a diagnosis of the piston chainsaw. First of all, to identify engine problems it is necessary to measure the compression in a cylinder. With its significant deviation from the manufacturer’s recommended values, you can safely claim that the surface of the cylinder or piston has scratches, scuffing, scoring. It is the drop in compression that is the reason for complete disassembly and repair of a chainsaw piston group.

To quickly diagnose the cylinder head for chainsaw compression ring failure or cylinder scoring, professionals advise removing the muffler and assessing their condition through the exhaust window.

Unrealizable operating logic of air boost.

Airflow in the room is not as easy as it may seem. The purpose of the air overpressure is to create the required excess pressure in the protected area in relation to the room where the smoke threat may originate.

But there is a door between the rooms. and this brings with it a lot of surprises.

The door should be open/closed even in the moment of fire alarm. how else will the evacuation happen??

So, when the door is closed and when the door is open, you need different air overpressure.

This is achieved either by using two different fans or by setting another valve to relieve excess pressure from the room with the air supply.

Both are based on smoke evacuation control by door opening sensor signal. Perhaps there is a way to control by measuring pressure, but it needs a very accurate sensor.

It is clear that this is a rather complex control scenario and not implemented in all systems.

I myself witnessed the inability to open the door to the elevator vestibule because it was pressurized by the difference in pressure when the air pressure came on.

Grass trimmer won’t start. what parts to check

Hand starters are used to start gasoline trimmers. By means of such starters, manual movement of the crankshaft is carried out

It is important to turn on the ignition, so that when the crankshaft rotates, the fuel-air mixture entering the cylinder can ignite. Ignition of the first portion of the mixture will start the engine, and the grass trimmer is ready for operation

However, very often it happens that attempts to start the engine come to nothing. Naturally, when after 5 attempts to start the engine, no success can be achieved, then it is necessary to proceed with the diagnostic measures. There is a special sequence, which should be followed in order to find the cause of why the lawnmower does not start, and successfully eliminate it. The sequence of checks has the following format:

• Check the fuel in the tank and the quality of the gasoline-oil mixture
• Determine the color of the spark plug, as well as signs of its functioning
• Make sure the air filter is working properly
• Check the fuel filter, which is responsible for cleaning the gasoline with oil that enters the carburetor
• Working order of the breather plug
• The reason why the lawnmower does not start can be the exhaust port or the muffler

These very nodes are the main sources of the problem of starting the grass trimmer with difficulty. A more complex problem is associated with a faulty carburetor, which needs adjustment. Let’s consider each component individually to find out the reasons why the grass trimmer does not start, and fix them with your own hands.

Carbon deposits on the grass trimmer piston

It is summer time, and lawnmowers routinely start mowing in homesteads. A great tool, powerful and mobile. With a gasoline grass trimmer you can cut the grass and get rid of dried weeds. However, there are cases where the lawnmower does not start, works intermittently or does not develop full power. It’s not a good time to work! And as they say, you pull the starter grip more than you mow.

It is not just older brushcutters that have had trouble starting, but also new ones. What to do in this situation?? There’s only one way out: take expert advice and benefit from their practical experience!

You’ve bought yourself a new gasoline grass trimmer and you’re having trouble with it right away. Very badly starts. If you do a little mowing and then turn it off, it’s even harder to start while it’s “hot” than when it’s “cold. What to do with it, I do not know how to start it correctly?

The instructions for starting a brushcutter go like this:

Pump up fuel with a silicon button (primer) located underneath the carburetor. You need to do as much (or a little more) than it is written in the manual, usually about 8-10.

Use stopping button to fix throttle lever at high revolutions.

yank the starter handle 2 or 3 times. The engine should “seize up.”.

If the engine “seized” and stalls, it is necessary to move air valve in 1/2 position and try to start it again. When the engine is running, turn off the throttle and turn the choke to the “open” position. Start working.

Performing manipulations on fuel pumping you should not be afraid of overflowing. If this happens, and, as they say, “filled the plug”, then unscrew it is not necessary, enough to move the air damper in the “open” position and holding the full throttle, while cranking the engine starter 2-4 times. After that you can start the engine and get to work.

The continuous running time of the lawnmower can be found in the instruction manual of the grass trimmer. On average, mow for 15-20 minutes, and then turn off the trimmer for grass and let it cool down for 3-5 minutes. The continuous operation time is also affected by weather conditions. In hot weather, mowing tall grass, overgrown weeds, overloaded grass trimmers overheat faster.

Many brushcutter problems are caused by incorrectly mixed fuel. In two-stroke engines, the lubrication is done with special oil (not conventional motor oil) mixed with gasoline!) mixed with gasoline. If the oil is not mixed with the gasoline, the lawnmower will fail quickly. Mix the oil and gasoline in the proportions listed in the trimmer‘s instruction manual. This is usually 1:40 or 1:50.

The question often arises: the proportion 1:50 is how much oil and gasoline?

50 parts of petrol for one part of oil. Hence: 1000 ml (1 liter of gasoline) divided by 50, you get 20 ml, that is 1:50.

This way you can figure out the composition of the fuel mix (gasoline/oil) in any proportion. To add oil to gasoline without “by eye”, you can take a 20 ml syringe of medicine, fill it with oil and “inject” it into a container for the fuel mixture.

For the run-in period of the engine (this is about the work of the grass trimmer on 2-3 tanks), the amount of oil can be increased. For example, mix it with gasoline in the ratio of 30:1.

too little oil in the petrol mix causes increased wear of the cylinder piston group. Too much oil in the mix is not fatal, but harmful. Piston rings may get corked, there may be rapid formation of soot in the combustion chamber, and the engine output may drop. In addition, the muffler screen gets corked. That is why some users (after the expiration of the warranty period on the grass trimmer) recommend to dismantle it.

The gasoline used in brushcutters is AI 92. The brand of gasoline is precisely prescribed in the instruction manual. You should not try to “force” the engine by pouring into it the 95th gasoline. This can lead to overheating, unstable operation of the grass trimmer and breakage.

It is not recommended to leave fuel in the trimmer’s tank if you don’t use it for a long time. It is better to finish the day’s work after the mixture is fully exhausted. if you do not do that, then, because overnight the gasoline from the engine will evaporate, but a thin film of oil will remain, it may clog the carburetor jets. It will cause difficulties the next time you start the engine.

It is also necessary to observe safety rules when storing fuel. Many people put gasoline in a plastic water bottle. Is it worth doing it that way??

In no case you should not store gasoline in a plastic container from under water. Static charge builds up while mixing the fuel mix and you can “catch” a spark.

That is why gas stations do not allow you to fill up gasoline in plastic cans, only in metal cans. Before pouring gasoline into a metal canister, it is better to put it on the ground so it removes static from the shell.

But there are situations when simple trimmer manipulation doesn’t help. The engine still will not start. In this case we check ignition and feeding system, following the rule “engine does not work if there is nothing to burn or there is nothing to ignite”.

The gas-engine trimmer likes cleanliness. You should keep the air filter and fuel clean. It’s better to let the gasoline you buy at the gas station stand for 2 days and put it through a simple filter. a piece of baize cloth.

We check the electrical equipment as follows:

We unscrew the spark plug, check the gap between the electrodes. We set the correct gap between the electrodes with the old-fashioned way. We take a razor blade, break it in half and put a home-made dipstick between the electrodes. If the blades enter tightly, the gap is perfect.

Put the cap of high-voltage wire on the spark plug and lean the spark plug against the metal surface of the engine. Yank the starter a few times. If the spark beats well to one point, the gap is adjusted correctly. If not. the spark is weak or “wandering”, you need to readjust the gap between the electrodes.

How to repair a chainsaw cylinder block?

To rebuild, the technician completely disassembles the engine and examines its working parts. Measurements are taken to accurately assess the condition of the equipment and understand what repair procedures need to be performed. During overhaul, it is possible to bore parts if they are made of suitable materials.

The restoration process also includes other steps:

• Evaluating the efficiency of the piston stroke, measuring the compression created in the working chamber;
• inspection of equipment integrity, looking for mechanical damage, scratches
• analyzing the condition of the piston fasteners, eliminating play and other problems;
• inspection of other equipment that affects the operation of the piston group.

To restore the chainsaw cylinder was successful, the master conducts a series of checks after assembling the equipment

It is important that the power corresponds to the factory parameters, and that the saw shows stable rpm during idling and under load. Only after such inspections can the repair of the equipment be considered complete

Piston burnout signs and symptoms

These two wonder-components burn, giving off more heat and at the same time have a small coefficient of expansion during combustion, and moreover, being in structure of gasoline, they also slow down the rate of combustion, reducing power. Consequently, when driving with such fuels to get proper traction you need to turn the throttle more than when driving with normal gasoline, but here is the misfortune: we get the necessary traction together with a much higher combustion temperature and excessive fuel consumption, and this results in a hole in the piston.

There are many factors which influence the piston performance and it is impossible to give an unequivocal answer whether a particular piston will burn out or some other defect will occur. It is possible to estimate the probability of occurrence of this or that event To avoid such unpleasant event as piston burnout, it is necessary to observe all rules written in technical manual. The piston blowout is purely an operational defect.