STIHL ms 180 fuel filter change

stihl, fuel, filter, change

Fuel system diagnosis and troubleshooting

STIHL chain saws may not start even when they are sparking. If this is the case you need to look for a problem with the fuel system. To do this, check the spark plug for wet patches. Its presence indicates excessive fuel. When the fuel mixture begins to literally flood the spark plug, it can not ignite it.

What to do if the spark plug fills up

The cause of a primed plug could be the carburetor or improperly starting a cold engine. Before getting into the carburetor, you need to “blow” the engine. This operation will require a certain sequence of actions:

Problems with chain saw plugs

  • Remove the spark plug;
  • Turn the STIHL chain saw upside down by draining the fuel;
  • in the same condition pull the starter grip several times to remove any fuel residue;
  • screw the spark plug back into place;
  • set the engine control lever to the hot start position;
  • pull the starter grip several times.

All this should be done with the ignition off and as far away from an open flame as possible.

If the problem is a cold start, blowing the engine off helps you get your STIHL chain saw working again. If the STIHL 180 chain saw will not start even after a flushing procedure, the carburetor may be the problem.

Design of the pump, lubrication system and principle of operation

The oil pump drive consists of two parts, a plastic gear with a worm gearing and a wire lever that transfers the power from the sprocket to the worm gear.

One of the main faults of the oil system of the saw is defective threads on the plastic pinion of the oil actuator, so whenever possible, it is necessary to check its wear and thread quality.

The lever is permanently mounted on the gear and they are delivered as one piece. The tip of the wire arm has a distinctive bend which is designed to engage better with the drive sprocket drum. Drum has a special groove for the drive unit.

The STIHL oil pump 180 is a metal pump that cannot be dismantled. The pump housing has an oil suction port and a channel through which the oil from the oil supply pipe gets straight to the pump. The mechanism is fitted into the STIHL 180 chain saw housing.

When engine speed is increased, the drum sprocket turns the worm gear by the wire lever, which in turn makes the oil pump plunger turn, and as a result the oil is pumped through oil channels to the chainsaw bar.

In the work of the system, is directly involved and the chainsaw oil pipe, at the end of which there is an oil receiver. The oil receiver is also a filter. On the second side of the oil hose, a rubber extension is made, through which the hose is installed in the chain saw STIHL 180 just behind the oil pump.

Actions when a malfunction is detected in various parts of the unit

Unpleasant phenomena such as loss of power, lack of connection, and idle support are common.

This behavior is caused by malfunctions in the chainsaw carburetor. This is manifested by contamination with dust particles, sawdust. Such a breakdown is no problem to eliminate on its own.

How to Change a Fuel Filter on a Stihl MS180 Chainsaw | L&S Engineers

Cleaning the carburetor is made with the application:

Sequence of steps, when making repairs:

  • To begin repairing the carburetor, start by cleaning off dirt and dust particles, fine wood. A brush is used for this. When the surface is completely free of debris, the repairman removes the cover, after which the filter.
  • The air collector is released after unscrewing the fasteners of the air filter. The user now has access to the gas pedal and linkages. The gas pedal lever is removed as soon as the choke is lowered by pushing down with the finger.
  • The carburetor is retracted from its seat after the choke lever has been removed and closed. Then the wire to stop the engine is removed and pulled on itself. The plastic lever, which is the attachment point for the wire, is removed.
  • It is raised on the left side. As a result, the carburetor is released, allowing it to be pulled out and cleaned. For this purpose it is convenient to use a compressor. In its absence, the parts are washed in clean gasoline.
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The process of assembling the carburetor is reversed. If after this process there is smoke from the muffler and the saw engine does not start well, it is necessary to make sure that there is a spring under the lever needle.

Spring loaded spark plug cuts off the fuel supply. No spark plug spontaneously overflows into the spark plug. It is important to check that the spring is in place and check that it is working.

If the spark plug gets stuck in gasoline, it should be dried. To do this, the part is unscrewed, drained, extra fuel that has fallen inside, through the available hole. Dry the spark plug for more than half an hour. Then it is put back in place and the chainsaw is put into operation.

Insufficient contact between the high-voltage cable and the spark plug end may also be one of the causes of tool failure. STIHL chain saw parts can be repaired by replacing problematic parts.

For example, if a spark plug fails, it is replaced with a reliable spark plug. Chains, chain sprocket, bars. wear out quickly. They solve anti-vibration tasks in the chainsaw device, so their replacement is urgent. It is recommended to keep such spare parts in stock.

Preparatory Step

Repair of any machine should begin with a preliminary step and the STIHL 180 is no exception. An early step before any STIHL 180 chain saw disassembly involves removing the side cover, the chain and the guide bar from the chain saw. Next, with a compressor and a brush, you need to clean the chain saw from dirt, sawdust, oil and other smudges.

When cleaning the chain saw, special attention should be paid to the area where the chain saw’s drive sprocket is located, t. к. This is the dirtiest part.

Where oil is heavily accumulated, of course wash with uncontaminated gasoline.

Trouble with the starter mechanism

Many problems arise when trying to start the engine of a new saw or a device that has been lying in storage for a long time. In this case you should:

  • Set the choke shutter switch to “closed” position;
  • Forced the fuel mixture by the pump into the carburettor;
  • Pull the starter rope to a position where you really feel the resistance of the motor;
  • Vigorously pull the starter rope several times. Usually after that the engine starts but immediately stops;
  • Move the lever to the operating position and pull the starter rope again. The engine should start normally.

How to change the piston on a STIHL STIHL 180 chain saw

If it is necessary to replace the old piston and install a new one, you must know how to do it correctly and follow a certain algorithm. Also need to have a small slotted screwdriver, a special STIHL combination wrench, a power screwdriver, a hammer, a mallet of soft material, a compressor and a stopper for the STIHL piston.

Before starting the work to replace the piston or piston assembly the chainsaw must be cleaned as thoroughly as possible. Next, the work is carried out according to the following algorithm:

  • Remove the top cover from the saw and unscrew the spark plug.
  • Remove the side cover.
  • Use a power screwdriver to remove the stops from the chain saw shock absorbers, and then disconnect its handle from the body.
  • Next, it is necessary to remove the drive sprocket and the starter.
  • Install the piston stopper in the spark plug hole and unscrew the flywheel nut and the clutch.
  • Remove the flywheel, clutch and oil pump worm gear that is located behind the clutch.
  • Unscrew the two screws fixing the carburetor and the air filter. Remove the filter, engine lever and STIHL carburetor.
  • Remove the ignition coil and muffler.

After all these operations are done, it is necessary to clean the saw of dirt once again, then turn it over with the bottom up and unscrew the four screws fixing the engine to the chainsaw body. After unscrewing the screws, the engine is separated from the housing and cleaned once again.

On the removed engine, unscrew and remove the sump, after which the piston complete with crankshaft is removed from the engine.

stihl, fuel, filter, change

when removing the piston from the cylinder, it is necessary to remember how it was positioned relative to the cylinder.

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Then loosen the piston pin retaining rings with a small screwdriver and disconnect the crankshaft from the piston.

In the case where only the piston needs to be replaced, you can install it on the crankshaft, then mount the piston pin retaining rings, positioning them so that the break in the retaining ring, pointing downward. This is necessary to prevent the rings from jumping out by themselves while the engine is running (see STIHL manual). Fit the compression rings, lubricate the cylinder with engine oil and assemble the engine.

The work of inserting the piston into the cylinder must be carried out with the utmost care, i.e. к. compression rings are brittle and break easily.

Crankcase is mounted on the engine, sealant is used as a gasket, and then four screws are mounted and fastened crosswise. Next, the engine is installed on the body of the chainsaw. The subsequent reassembly follows the reverse of the disassembly algorithm.

When you need to adjust the carburetor of the STIHL 180

To begin with, it is worth determining why you may need to adjust and repair the carburetor STIHL ms 180 at all. So, it is necessary to do it in the following cases:

  • If the chain saw doesn’t keep idle speed;
  • A repair may be necessary if the saw does not start;
  • Loss of power;
  • High fuel consumption;
  • The chainsaw will not reach its maximum rpm.
  • If your chain saw does not hold idle; or if it cuts off after revving.

This list can go on and on, but the main reasons we have identified. Before proceeding to the adjustment, it is necessary to know what the main parts consist of the carburetor on the STIHL 180 chain saw, and who makes it.

Components of chainsaw fuel system

Having made a superficial acquaintance with the system and its construction, let us consider each of its elements with all the attention to the nuances. How different are the shapes of the same parts in different chainsaw models and how they can be installed. information about the components of the fuel system, with side-by-side photos, below.

Chainsaw tank

In most models, the fuel storage tanks are built into the body and represent a monolithic structure with a handle. If the tank is burned or mechanically damaged the gas lever and air valve must be completely reconnected (in addition to the hoses). There are some systems that at first sight seem to be separate, such as the STIHL MS 440, but even there the tank is permanently attached to the housing and is not sold separately from the handle.

In addition to the chainsaw body the fuel tank can be located in the crankcase (for example, Partner 351). In this case, the process of replacement when damaged, more time-consuming and labor-intensive, because it requires disconnecting almost all the nodes of the tool, including the engine. Fortunately such designs are not always monolithic and there are tools where the fuel and oil tanks can be removed (STIHL MS 180), making repairs much easier.

Fuel filter

An important and popular staple that protects the carburetor and engine from dirt and premature failure. According to the type of design, there are 2 varieties of filters: in a plastic housing and in a metal one. Nylon (in plastic Chinese elements), felt (in all types of bodies), cortex (in plastic) and foamed polymer (in metal) can be used as a cleaning material.

Regardless of the material, every fuel filter for chain saws has a weighting piece that directs it to the lowest part of the tank when the saw is tilted.

Polymer foam and cortex provide the highest degree of protection against small particles. Felt is no less reliable, but rather quickly clogged. Nylon nets for such purposes categorically are not suitable, therefore, having got the Chinese saw with similar equipment, it is better to change it at once for one of the above mentioned. The replacement must have an identical fitting diameter, which can be 3.5, 4.5 и 5.5 mm.

Fuel hose

The most flexible part of the system, performing the transfer of fuel from the tank to the carburetor and primer (if any). The budget versions are made of silicone and equipped with a gasket in the form of a bushing or without it at all and just fits tightly into a hole in the tank. Better quality hoses are made of high-density gasoline-resistant rubber and have special tabs pressed to the tank from both sides as sealing contacts.

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Of course, in terms of durability, a special rubber fuel hose for chain saws can withstand longer use before it starts to dry out and crack.

The classic chainsaw system has only one fuel line connected to the carburetor inlet fitting. If you have a hand pump (primer), the number of hoses increases to 3, where the first performs the main role, the second connects the carburetor and primer, and the third removes excess fuel from the primer back into the tank.

Check valve (breather) of chainsaw

The devices are small in size, but very important for the entire fuel system. Located on top of the tank and provides pressure regulation when the volume of fuel decreases. Of the most common, we can distinguish 2 types of breathers: simple (cone-shaped) and collapsible (float). Both variants are widely used, both in amateur and professional tools.

In addition to the standard valves, some models have something quite unique. For example, to replace the breather plug on the Makita EA3203S and the STIHL MS 660 you need a completely identical replacement part.

If the passage channel of the valve is clogged, the air necessary to normalize the pressure against the fuel being pumped out will stop flowing into the tank. Since the tank is sealed, a vacuum will begin to form in it. With each new “eaten” batch of fuel, the carburetor will find it more and more difficult to pump. At this rate, the operation continues for several dozen seconds until the diaphragm pump is up. If the tool stalls because of a clogged breather, then when you unscrew the petrol tank plug, air will be sucked in sharply, normalizing the pressure.


The main distribution mechanism and the intermediate link between the petrol tank and the combustion chamber. Includes a diaphragm-type pump, which works due to air supplied from the engine crankcase through a pulse channel. The second connector is connected to the fuel hose that conveys the mixture from the tank. If the chainsaw is equipped with a primer, a modified carburetor model is installed, with an additional (third) connector.

A variety of device shapes and designs, comparable to the number of tool models on the market today. Many motor saw carburetors have unique features of the structure, but there are also popular standards that have a significant scope of application. Universal carburetors can be both factory-made (Walbro, Zama) and underground (no name on the top cover).

Breakdowns of these mechanisms, in most cases are based on wear or deformation of the membrane, needle or rocker arm. Reduced fuel flow can be due to a clogged filter, and improper RPMs due to a knocked-down adjustment screw setting. Despite the multifaceted design, restore the functionality of the carburetor by force for everyone, if you have the desire and the right instructions, which is devoted a separate topic on this site.

Chainsaw primer

A simple hand pump that forcibly pumps fuel into the carburettor. To be used before starting the engine to simplify starting. The device consists of a transparent silicone dome, and a plastic base with two nozzles (short for drawing in, long for removing the mixture). The short connector is connected to the carburetor and the hose going to the gas tank is connected to the long connector.

The principle of the primer is based on sucking fuel through the carburetor of a chainsaw. When you press the dome, the mixture (or volume of air) flows into the tank, and when you release it, it is drawn in. The tank of the carburetor, as an intermediate link between the two hoses connected to it, is filled, and the excess passes further into the primer and returns back into the gas tank. Usually 2 or 3 presses are enough to fill it, but even if you do 100, nothing bad will happen as the mixture will simply circulate in the system (except the dome will be worn).

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