How to disassemble a STIHL chainsaw

STIHL MC 180 disassembly and assembly

Before you can disassemble the individual components of your STIHL chain saw you first need to do some preparatory work: remove the side cover, the chain and the guide bar. Next, clean the entire housing from dirt, oil and gasoline residue, and clumped sawdust. If there is a lot of oil leaks and you can’t remove it by mechanical cleaning, use kerosene, gasoline or VD-40.

Removing the Handle

The STIHL chain saw handles are held in place by three shock absorbers. First you need to take out the plastic plugs from the middle of the rubber gaskets. Then with a piece of thin fitting or a thick screwdriver press out of its seating hole the upper gasket, which is next to the rear handle. Then the middle shock absorber is dismounted.

MS291 stihl chain saw disassembly

To remove the third shock absorber turn the housing away from the inside of the handlebar and remove it by pulling in the opposite direction from the shock absorber.

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Remove the starter motor

When the upper cover of the STIHL chain saw body is removed, you need to unscrew the 4 mounting screws of the starter motor. Then the oil tank and fuel reservoir cap will be accessible. The starter does not hold anything in place, it is easy to dismantle.

When the starter is removed, you need gasoline or VD-40 to clean the interior cavity opened, it is usually a lot of small compacted with oil leaks resinous sawdust. If this thick layer of solvent is very thick, you need to scrape it off with a wood chip before using it.

Handwheel removal

Handwheels are screwed very tightly on chain saws and STIHL chain saws to prevent play or unscrewing. To remove the flywheel, you need a 13 mm ring spanner, a detachable head with a metal lever, or a powerful wrench.

To fix the crankshaft, you need to remove the spark plug and through the resulting hole block the piston by inserting a rope of twisted knots.

Completely unscrew the nut is not necessary, you can stop when the top surface of the nut will be flush with the end of the shaft. Then through the spacer you need to make the handwheel of the chainsaw to jump off the crankshaft, and then it is very easy to remove it by hand, without special tools or shock loads.

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Disassembly of clutch and oil sucker system

To get to the STIHL chain saw clutch you need to remove the sprocket from its mounting. It is necessary to take out a washer. stopper from fixing slots on a crankshaft, remove bearing, sprocket and gaskets.

We unscrew the clutch with a hexagonal head for 19. Here thread is not standard, left handed, unscrew to the side of the guide bar.

disassemble, stihl, chainsaw

After fully unscrewing the clutch and putting it aside, remove the deflector plate from the crankshaft and the oil pump drive. There are no circlips, you can remove it by hand.

Carburettor block, ignition coil and muffler

STIHL chain saw carburettor can be removed with a hexagon socket or ring spanner 8 and a lantern piece. An extension cord is needed to unscrew the nuts of the carburetor block and the air filter.

Before you remove the carburetor from its place, it is not superfluous to disconnect the installation wires going to the ignition and to the air damper rod from the motor control knob, as well as dismantle the lever. After these operations nothing will interfere with removing the carburetor and air filter.

To remove the muffler simply unscrew the two mounting nuts and pull the muffler away from the housing.

The spool can be easily removed by unscrewing the two screws on each side of the spool base.

Removing and Disassembling an ICE

The heart of every power tool is its engine. STIHL chain saw engine is held in the housing by 4 hardened bolts from below. Unscrew them completely and slowly remove the motor from its seats, especially carefully through the rubber tube of the carburettor.

The crankcase is also supported by 4 bolts. After the crankcase, you can remove the crankshaft along with the oil seals, bearings and piston rings.

When removing the oil seals and bearings may need a special puller, if they are pressed on the drive shaft with force.

To remove the piston from the connecting rod of the Stihl chainsaw engine requires removing the stop ring with a screwdriver from its seat. Then on the opposite side of the circlip we press out the piston and the piston is easy to remove.

Chainsaw assembly

After a complete disassembly you must first assemble the engine separately and then assemble all the components of the chain saw in reverse order of disassembly. The final step will be the installation of carburetor unit rods and ignition mounting wires.

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Design and diagram

The STIHL chainsaw 180 (like the STIHL ms 660) is not an easy saw, because of the way the machine works. To familiarize yourself in detail with the specifics of its operation, it is necessary to study the instruction manual of the STIHL ms 180 chainsaw.

Instructions for use

Here is a schematic drawing of the chainsaw, with all the details of its component parts and first and second starts. To keep the device in good condition and be sure of its performance, you need to know the basics of its construction and principle of operation. Also for better performance, you need to tune your chainsaw‘s carburetor.

Series product equipment consists of:

  • Ematic guide bar;
  • The Oilomatic saw chain;
  • Adjustable oil pump to distribute oil evenly over the entire chain and ensure excellent system performance;
  • The carburetor with a special STIHL compensator, which regulates the optimum engine power;
  • An air filter;
  • The starting lever (cold and hot);
  • Control lever;
  • Handle with special anti-vibration system.

Complete assembly of STIHL 180 chain saw

The STIHL MS 180 is a reliable and undemanding tool, but it needs repairs just as much as any other machine. Next, let’s take a look at how the STIHL mc 180 chain saw disassembles, which requires a complete engine overhaul

Advance Step

Repair of any machine should start with a preliminary step and the STIHL 180 is no exception. At the first step, well in advance before the disassembly of STIHL 180 chain saw, you must remove the side cover, chain and guide bar from the chain saw. Next, with a compressor and a brush, you need to clean the chain saw from dirt, sawdust, oil stains and the rest.

Particular attention during cleaning should be paid to the area where the chain saw’s drive sprocket is located, t. к

In places where there is a huge accumulation of oil, it is an option to wash with unstained gasoline.

Handle Removal

Specific disassembly STIHL 180, begins with the removal of the handle, which is attached to the body of the chain saw with 3 rubber shock absorbers. To remove the handle, you need to remove the plastic plugs from the inside cavity of the shock absorber, then using a strong screwdriver, first squeeze the upper shock absorber, then the one closest to the back handle.

In the back of the handle is the throttle trigger, which is connected to the carburetor through a wire rod, if you set a goal to disconnect the rod from the throttle trigger, you need to unscrew the two screws and disassemble the handle.

When the handle remains on one shock absorber, it is necessary to unscrew the chainsaw body from the inner part of the handle and, breaking to the side, remove the body from the last rubber.

Starter removal

Next, remove the upper cover of the housing and unscrew the 4 screws fixing the starter, then you need to remove the oil tank and fuel tank covers. The starter can be removed quite easily and there should not be any troubles.

After removing the starter motor, the interior of the chainsaw should be cleaned. к. there is usually a lot of compressed small sawdust on the housing under the starter.

Handwheel Removal

The chain saw STIHL 180 flywheel is screwed in with a great effort, to remove it you will need a head with an iron screwdriver. The nut holding the flywheel is unscrewed with a 13.

To block the crankshaft from turning, you need to unscrew the plug and through the candle hole to install the piston stopper, if it does not exist, use the old starter cord from the starter, with the knots tied to it and immersed in the cylinder through the candle hole.

Never use a screwdriver or any other tool to hold the flywheel from turning between the ribs and housing, because this method of rotation lockout can break the flywheel blades and cause severe damage.

and parts overview of the STIHL MS180 chain saw.

Disassembling a STIHL STIHL 180 chain saw. Part 1

Here’s a quick video to show you how to change the piston on your STIHL chain saw

If the piston in the cylinder is blocked, of course unscrew the flywheel nut. The thread in the nut is straight, so it is necessary to twist to the left side. After loosening the nut, remove it to the end, you will not remove it completely, rather twist until its top edge flattens with the tip of the shaft, after which the mallet of soft metal installed on the nut and made a sharp blow to it. Thus, from a sharp blow, the flywheel slips off the shaft and it can be simply removed without any additional tools.

Removing and disassembling the engine

The engine is held in place by four screws on the bottom of the STIHL 180. To remove it is necessary to unscrew them, and then carefully remove the engine from the seat and the rubber spigot of the carburetor.

To disassemble the engine unscrew the 4 screws of the crankcase and remove it, then you can remove the crankshaft complete with oil seals, bearings and piston rings.

Removal of bearings and oil seals usually does not require additional tools, but if the bearings were pressed on the shaft with force, then for the dismantling require a special puller.

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To remove the piston from the connecting rod, you need to remove the retaining ring from the housing, with a thin screwdriver, then from the opposite side press out the piston pin, after which the piston is removed to the side.

Performance and Technical Data

As for the technical and operational characteristics of this chainsaw, they are in many ways superior to all modern market counterparts. To learn how to run the chainsaw properly, see here.

The STIHL 180 chain saw is engineered to deliver maximum performance without making you feel uncomfortable. The unit is totally vibration-free and does not fatigue the operator’s hands.

The handle, which girdles this tool, “sits” tightly on 3 shock absorbing blocks made of rubber, which is also very convenient for using the chainsaw.

The STIHL ms 180 chain saw has the following specific features:

  • Max. displacement is 31.8 cc³;
  • Nominal weight of only 3900g.;
  • Power level is 1.5 kW / 2.0 L.с.;
  • Bus length is 0.35 м.;
  • Characteristic Oilomatic type chain with 3/8″ pitch (PMC3);
  • A tank with a capacity of 250 cm³;
  • Idle speed is 2800 rpm;
  • Specific weight is 2600 g/kW;
  • Permissible vibration level is 6.6 to the left and 7.8 m/s2 to the right;
  • The sound pressure is 97.0 dB;
  • Sound power. 106.0 dB.

Simple operation, no maintenance other than timely lubrication (if you don’t keep an eye on the lubrication system, you can kill the bar and chain).

It’s worth noting that the two-stroke engine of this machine is designed in such a way that it runs on a gasoline-oil mixture. Only high-quality STIHL chain saw oil should be added to your gasoline. information on STIHL chain saw oil is available here.

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The quality of these operating elements has a major impact on the function and longevity of the system.

STIHL chain saw 180 in the owner’s manual

This is essential for warranty repairs and to extend the life of the chain saw. It is important to use good chain oil for your chain saw

STIHL 250 chain saw malfunction (chain saw carburetor malfunction):

Right after starting the chainsaw goes into high gear, but if you step on the gas, instead of starting it accelerates, it “sinks” and even shuts down. Or it starts up poorly, does not rev up and shuts down (this fault also applies to other more expensive chain saws with a booster pump in the carburetor).

Cause of chain saw malfunction: Rubber sleeve on booster pump piston in carburetor (fuel booster) is worn. This leads to air suction in the booster pump and the main nozzle supplies a lean fuel/air mixture into the nozzle (there is not enough gasoline in the mixture) and the chainsaw first runs at higher rpm and then “crushes” and shuts down. This happens after 2 or 3 years of use and usually during the hot summer months.

Main malfunctions

The chainsaw must be used according to the instruction manual so that it will have a long service life and will not break down. All STIHL chain saw faults can be diagnosed and repaired by yourself. Let’s look at the main malfunctions that can occur in the nodes and design of the device, and how to repair the STIHL 180 chain saw with their own hands.


If you see a wet spark plug on your STIHL chain saw it could be a fault in the fuel system. The engine must run on a mix of petrol and oil. Poor mixture reduces performance, overheats the cylinder and wears out the saw’s systems. Wet spark plugs on STIHL chain saws are caused by an incorrectly mixed fuel mixture. Lack of air in the mixture prevents proper combustion of the emulsion.

Use of low-quality gasoline can lead to engine wear.

Oiling of the plug also causes the use of oil for 4-stroke engines, wear of the pistons. If such a malfunction occurs, it is necessary to remove the fuel tank cap and adjust the fuel supply. The air inlet must be repaired. If the filter is clogged, it should be blown out with air, or better yet, replaced. How to clean the filters is described in your chain saw operator’s manual.

The mixture quality can be determined with the help of a spark plug insulator. If it shows a brown color, it means that the mixture is of normal quality. The white color or soot indicates a lean or over-enriched mixture.

Plug may be the reason for oily spark plugs. Intermittent spark formation can be observed if the gap is set incorrectly. The Owner’s Manual gives the distance between the spark plug pins. If you don’t have this information, you can set it at 0.7 to 1 mm.

If the gap is smaller, the efficiency of ignition of the mixture decreases, if it is larger, then there are interruptions in the formation of the spark. To eliminate the over-enrichment of the mixture, you can blast the engine. To do this, remove the spark plug and turn the crankshaft a few times with the hand starter.

The chain is not lubricating

If chain saw is being repaired, you may notice that there is no oil in the chain. If the chain is not lubricating then the lubrication system is malfunctioning. There are such faults:

  • The chain is dry and has a light color.
  • The chain is stretching too fast.
  • The tire is too hot and the paint on it has melted.
  • Oil in the tank is not draining.
  • When the chain is sharp, the saw does not cut as well as it should.
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These signs indicate that the lubrication process has been disturbed. To check if there is oil in the lubrication system, remove the bar and turn the chain saw on. Then increase the revs and watch the oil line end point. If oil is flowing, it means there is not enough oil to properly lubricate. If no flow, clean filter. Also the oil flow should be checked. If there is no problem, you will need to do some more diagnostics and do it yourself. If it turns out that the substance is not fed, then the oil system is repaired.

Let’s look at the main malfunctions and methods of troubleshooting:

  • Oil hose breakage. This can be seen upon inspection. You need to replace the hose.
  • If there is no thread on the shaft of the oil pump, you should replace it.
  • If there are thread defects, the threads must be replaced.
  • If the main shaft is missing a corkscrew, you can install a nail of the same diameter in its place.
  • The filter could be clogged. This happens all too often with the STIHL MS 180. You can flush it with gasoline. If this does not solve the problem, the filter has to be changed.

STIHL 180 chain saws often have a leaky oil line. This is where the oil line coming from the tank is inserted into the body of the tool. You can tell when there is oil leakage on the bottom of the saw.

To fix the problem, you must remove the saw handle, pull out the hose. After that you need to clean the hose. Then apply sealant to it and place it in the body of the tool.

Will not start

If the chainsaw does not start, then the cause may be a failure of the ignition and engine start unit. If no deviations are found when measuring the gap between the module and the flywheel, you should check the spark plug. It is pulled out of the shaft and the clearance is measured. If the fuel enters the combustion chamber and there is no failure in the ignition system, then the carburetor is defective.

Does not rev up

If the saw does not maintain idle speed, the following may have occurred:

For self-repair you need to perform the following actions:

  • Clean or replace the fuel hose.
  • Clean filter.
  • Check oil and gasoline quality.
  • Check the operation of the carburetor and spark plugs.

STIHL chain saws work properly when repaired.

If the saw does not pick up speed, this could be the cause:

  • faulty engine;
  • cylinder wear;
  • failure of piston rings;
  • The spark plug is broken;
  • A faulty coil;
  • Unbalanced carburetor screws.

If no defects are found after testing, the carburetor is checked.

Main chainsaw chain problems

It is not uncommon for chainsaw users to have trouble tensioning the saw chain. It either loosens spontaneously or stretches and comes off. These problems are usually caused by machine breakdowns. Therefore, before starting the chain tensioning procedure, you should check and eliminate possible causes that can lead to misalignment.

The reasons that the chain on the chainsaw stretches, can be high loads or insufficient lubrication on the bar. Because of it the saw overheats, the metal expands, the size of the saw element increases, and it comes off the bar. Oil flow can be interrupted if the pump is broken, the channels are clogged, or the oil hose is broken.

If you have changed the chain on your chainsaw to a new one, then be prepared for the fact that during the running-in period it will stretch a little. It is only necessary to check the tension in time so that the element does not fly off the rail.

When the driven or driven sprocket is worn, the effectiveness of the chain links is reduced, which causes the saw element to fly off. In this case you will have to unscrew the chain drive and change the sprocket. The saw blade can also come off because it has been stretched or the guide bar is deformed.

If the chain on your chain saw is loose, the tensioning mechanism may be broken.

Common Breakdowns on the STIHL 180

Common faults on STIHL chain saws include:

  • The starter cord breaks;
  • Wear on the drive sprocket;
  • Leaks in the chain lubrication oil system;
  • Worn worm gear of oil pump;
  • Air intake through the oil seals into the engine crankcase;
  • Lack of spark on the spark plug;
  • Lack of fuel supply in case of failure in the carburetor (we will not dwell on them, as the repair and adjustment of the carburetor of chain saws, the issue is wide enough and will be discussed in a separate article);
  • Breaking of the lug of the seat for the engine control lever.

Now let’s take a closer look at the faults and start with the oil pump repair.

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