DIY homelite csp 4518 chainsaw repair

The chainsaw is a worthy replacement for hand saws and axes. Today, this tool is available in almost every household - it is indispensable for setting up a personal plot, construction and repair work. Intensive use and improper care of the tool can lead to premature failure. However, the owner of the chainsaw does not have to go to the workshop right away - many of the faults that can happen to her during operation are quite realistic to eliminate on their own.

Correct diagnosis is essential for a successful repair. Therefore, in order to determine why the chainsaw failed and, most importantly, how to make it work again, you first need to know the features of its design.

It should be noted that it does not differ in particular complexity, since it includes:

• engine (two-stroke gasoline);
• functional part (saw bar and chain);
• systems that ensure the joint operation of these two units (ignition, filtration, lubrication, etc.), that is, the tool as a whole.

In order to simplify the diagnosis of malfunctions, it is customary to distinguish them into two main categories:

• engine malfunctions;
• malfunctions of other parts of the chainsaw.

Most often, failures occur in the engine systems, however, the rest of the tool, due to intensive use or improper care, can fail at any time. How to determine exactly where the breakdown occurred? Simple logic will help us with this.

If the problem is in the engine, it will:

Video (click to play).

• do not start;
• deafen;
• work unstable;
• overheat;
• smoke;
• develop insufficient power.

As for all other malfunctions, as a rule, they manifest themselves with a normally operating motor.

If your chainsaw won't start, the first thing to do is to check for a mixture of fuel in the tank. By the way, it must be prepared in the proportions indicated by the engine manufacturer, otherwise the instrument will simply not start.

After verifying that the fuel mixture is correct and available, the ignition system should be checked. To do this, you need to inspect the spark plug.

Her condition can say a lot:

indicates that the fuel mixture does not enter the carburetor, which means that the problem is not in the ignition;

is the result of an overabundance of the fuel mixture, which lies either in a violation of the engine starting algorithm, or in an incorrect carburetor adjustment;

this is a signal about the presence of low-quality oil in the engine lubrication system, incorrect carburetor settings, or an incorrectly prepared fuel mixture.

If the spark plug is splashed with fuel, wipe it thoroughly after removing it. The fuel supply system should also be cleaned. To do this, it overlaps, after which the starter is turned on. A carbonized candle must be carefully cleaned with an awl and emery.

When checking the spark plugs, you should pay attention to the distance between the electrodes (the normal gap is 0.5-0.65 mm), as well as the condition of the gasket and the presence of a spark. A damaged or worn gasket will have to be replaced, and the spark can be checked by putting on the ignition cable, connecting the cylinder and plug nut, and starting the starter.

If the discharge does not occur, the plug must be replaced. In the event that a spark does not appear with a new candle, then the problem is in the connection to the high-voltage wire or in it itself.

If the fuel mixture does not flow into the cylinder, but the spark plug is working properly, this may mean that:

1. Clogged fuel filter.

To clean this unit, remove the fuel hose and check the jet. If it is weak, the filter must be removed through the filler hole of the fuel tank and cleaned or replaced if completely worn out.

As a preventive measure, it is recommended to replace the fuel filter at least once every 3 months.

This is nothing more than a hole in the fuel tank cap, which is cleaned out with an awl.

1. The fuel mixture is not supplied or is supplied insufficiently.

There may be several reasons for this:

• the air filter is clogged (in this case, it must be removed, rinsed with water, dried and replaced);
• the carburetor settings are out of order (which means this unit needs to be re-adjusted);
• the integrity of the carburetor membrane is broken (must be replaced);
• the channels of the carburetor are clogged (it must be disassembled and all parts and assemblies must be cleaned).

If at low speeds the engine of the chainsaw works normally, but at high speeds it starts to stall and smoke, the problem may be hidden in the muffler.

To check the quality of its work, you should do:

• dismantling (with the obligatory closing of the outlet);
• disassembly (if the muffler is collapsible);
• cleaning from carbon deposits using special detergents or dry method;
• drying (using a hair dryer);
• reassembly and assembly.

Dry cleaning without respiratory protection is not recommended. The carcinogens present in the soot will be released into the surrounding atmosphere in the form of dust, the inhalation of which is extremely hazardous to health.

To prevent clogging of the muffler during the operation of the chainsaw, you should carefully monitor the composition of the fuel mixture and the quality of its components.

If the chainsaw engine does not start or cannot develop normal power, it is likely that sufficient pressure does not build up in the engine cylinder for combustion of the fuel mixture. The reason for this may be the wear of the elements of the cylinder-piston group - the piston, rings, bearings, etc. In order to assess the condition of this unit, it should be visually inspected, having previously removed the muffler.

For a more complete diagnosis, a compression gauge is placed in the spark plug hole of the two-stroke engine of the chainsaw. It measures the compression in the engine. Based on the results of the check, one can judge the state of the CPG, however, the exact facts can only be obtained with a complete disassembly of the unit.

If the piston is chipped or scratched, it will obviously need to be replaced. The same applies to deformed or broken piston rings - for normal engine operation, they must be completely intact and free of carbon deposits.

A properly working carburetor guarantees maximum efficiency of the chainsaw, that is, it is possible to develop full power with the most economical consumption of the fuel mixture. The adjustment of this unit is usually carried out by the manufacturer, but its design provides for the possibility of adjustment already during operation.

The fact that such a setting will have to be performed by the owner of the chainsaw is evidenced by:

1. Strong vibrations or damage to the protective cover.
2. CPG wear.
3. Carburettor clogged.
4. Inability to start the engine or its spontaneous stops after starting.
5. Increase in fuel consumption and emissions while decreasing engine power.

Chainsaw carburetor adjustment is carried out in strict accordance with the manufacturer's instructions using three special screws, which are responsible for the maximum ("M") and minimum ("L") revolutions, as well as the idle speed of the engine ("T"). In order to exclude unwanted interference by an inexperienced user with the carburetor operation, some manufacturers install only one idle screw.

Carburetor adjustment is carried out in two stages:

1. Basic (carried out with the engine off).
2. Finishing (carried out with a running, pre-warmed engine).

For basic adjustment, screw in screws H and L as far as the stop and back out 1.5 turns. Final adjustments require the engine to warm up for 5-10 minutes at low revs.

The final calibration is performed by unscrewing the idle screw until the minimum engine speed is reached (in this case, its operation must be stable, and the chain must be stationary). If the engine stops at idle speed, the screw must be returned back, and if the saw chain is still in motion, continue turning counterclockwise.

Calibration check is performed by test:

1. Acceleration (with a smooth press on the accelerator, the engine should quickly pick up speed to the maximum indicator).
2. Maximum speed (if there is an ignition interruption, screw H should be slightly loosened).
3. Work at idle speed (the chain should not move, and the engine should pick up speed as quickly as possible).

If the owner of the chainsaw is not familiar with the carburetor device and does not have the tool necessary to calibrate it, contact a specialist. The carburetor is a very complex unit, so any wrong action can lead to irreversible consequences, for example, complete engine failure.

If the diagnostics showed that everything is in order with the engine and its systems, then the cause of the malfunction should be looked for in other units of the chainsaw. The most common problems are:

• failure of the starter;
• improper operation of the lubrication system;
• incorrect operation of the chain brake;
• saw chain wear, etc.

If the cause of the tool failure is not visible to the naked eye, as is the case with the engine, it is necessary to perform a thorough diagnosis of the faults and eliminate them in accordance with the manufacturer's recommendations and safety regulations.

The chainsaw has become such a familiar and necessary tool in the hands of a skilled man that if it fails, we begin to feel uncomfortable. But the design of this unit is so simple that we can make almost any repair of its components ourselves. But what is needed and how do you repair a chainsaw with your own hands?

You need to have a very small set of tools for this:

• a set of keys (including a special key for spark plugs);
• a diagram of the chainsaw device (usually it is included in the delivery set).

You also cannot do without elementary knowledge from the physics course. Add to that the ability to reason logically and you are almost ready to fix your chainsaw.

We will begin the repair with the "diagnosis" - the definition of the malfunction. First you need to unscrew the candle and inspect it carefully. Possible problems are listed below.

Types of spark plugs for chainsaws.

The candle is damp. We make a logical conclusion that the fuel mixture inside the combustion chamber does not ignite. The second reason may be water trapped in the cylinder. In any case, you need to dry the candle, blow out the cylinder. We do the same as when starting the chainsaw. The only difference is that the fuel supply valve must be closed and the throttle valve must be fully open. After that, we put on a cradle from the wire on the candle and check for the presence of a spark by pressing the candle against the cylinder body and trying to start the engine. If the spark is good, the reason may be the fuel - it needs to be replaced. If the spark does not appear or appears unevenly, then the cause of the malfunction should be sought in the ignition system. There may be a breakdown in the high-voltage wire or damage to the spark plug itself. It is enough to try using a spare plug to make sure that the first plug can still be used. If the spare plug does not respond to the start-up test, then the ignition system should be examined more thoroughly.

The candle is dry, but heavily soot-coated.This fact indicates that the balance between fuel and oil is imbalanced (there is too much oil!) Or one of the filters is clogged (fuel or air). Clogged filters first leads to a loss of power of the chainsaw, and then to its complete stop. Dust that gets inside the cylinder cannot be completely burned and settles on the inside of the cylinder in the form of a dense layer of soot.

Chainsaw fuel system: 1 - fuel filter, 2 - carburetor, 3 - manual pre-priming pump.

This drawback is eliminated as follows: the fuel is replaced, the fuel filter is cleaned (according to the instructions), the air filter is washed and dried. The candle itself is mechanically cleaned of soot using an awl, its contacts are cleaned with fine sandpaper.

The candle is dry and clean. Apparently, no fuel enters the cylinder at all. The cause may be either a clogged conductive tube or a problem with the carburetor. It is necessary to clean the fuel line of the chainsaw and check the operation of the fuel pump and carburetor. Repairing the named chainsaw units at home is almost impossible, so they are simply replaced.

Regarding the carburetor of the chainsaw, several important points still need to be clarified: manufacturers minimize the possibility of adjusting it, leaving access only to adjusting the idle speed. But even such a small amount makes it possible to achieve maximum power from the chainsaw.

By adjusting the idle speed correctly, you will notice that the engine runs more reliably.

But it is better to entrust the repair of the carburetor to the service specialists, since it can be done independently only with a lot of experience and certain knowledge.

Chainsaw two-stroke engine diagram.

We will assume that you were able to do everything accurately and your chainsaw began to show signs of life, but there are problems with power. It happens very often that the engine works well at idle, but the chain speed increases very slowly when the accelerator lever is pressed, or the chainsaw simply stalls. The problem may be that the exhaust gas outlet is clogged. It is not difficult to eliminate this deficiency.

First you need to unscrew the muffler. The piston must be set to the uppermost position so that it blocks the channel and excludes the possibility of soot getting into the cylinder. And now the soot must be carefully scraped off the walls. You can use both a screwdriver and a thin chisel for these purposes. When cleaning, we try not to make great efforts, as you can easily mechanically damage the cylinder or piston. After removing the plaque, we wipe the cleaned surface with diesel fuel or gasoline, and the muffler can already be screwed on. Before this, the non-separable muffler should be washed with diesel fuel or low-octane gasoline and dried. Removing the soot will increase the power.

It is possible that none of the described home repair methods have led to the desired result and the chainsaw still does not work. Most likely, you have a malfunction in the ignition system. It turns out that both the fuel comes in, and the spark on the spark plug is excellent, and the engine refuses to work.