Stihl Trimmer Dies When Hot

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Are you having trouble with your Stihl trimmer or edger dying or stopping? Don’t worry. It is a common problem with many trimmers. In most cases, it is due to overheating or other engine defects triggering it to die. 

In a nutshell, Stihl trimmer dies when hot to save the engine from crashing due to heat buildup and friction. However, your trimmer doesn’t have to do this regularly. When new, it should be able to withstand some of these adverse effects for some time.

So if your trimmer is new and is often dying off when in operation, then there is a defect. Luckily, there are ways you can locate these defects and ultimately eliminate them with no time. Keep reading to learn more.

Stihl Trimmer Dies When Hot

Stihl Trimmer Dies When Hot
Stihl FS 111 R

Overview

As mentioned above, most trimmers have an automatic safety switch that turns off the engine if it gets too hot. The function prevents damage to the motor and preserves its lifespan.

After a while, however, your trimmer shouldn’t be killing itself regularly. If yours continues to do so, you need to figure out why it’s overheating so you can fix the problem. Overheating can happen for several reasons:

  • Moisture causes a gas mixture to build up in your fuel tank and lines—or water might even have infiltrated your oil reservoir, making your engine run hot.
  • It may be due to a lack of lubricant in your fuel or oil, leading to extreme friction on your engine parts, overheating things, and making your trimmer shut down early.
  • Also, it may be due to dirt particles getting into vital areas and grinding them down from the inside out, leading to more friction than normal.
  • Finally, it may be due to cutting dense grass or other plants over long periods without giving it any rest breaks.

Possible Causes and Solutions

The Stihl trimmer will run when cold but dies when hot. That’s not the way it should be, right? Well, there are a few reasons why this is happening.

1. Clogged or Dirty Carburetor

You may have dirty fuel lines or a clogged carburetor. The carburetor may also be flooded; you’ll know if this is the case when you see gas leaking from around the engine’s base. Finally, one or more parts in the carburetor could be worn or broken, including the diaphragm, gasket, needle valve, and float.

So to determine if your problem is a clogged or dirty fuel line or a clogged carburetor, try cleaning any dirt on the parts. First, drain all the gas from your trimmer and remove both spark plugs from its engine to clean out these areas.

Then spray compressed air into each end of both fuel lines to clear them out and wipe down any dirt on their surfaces with a soft cloth. If this doesn’t work, you can clean out your carburetor using some small brushes (available at most hardware stores) to scrub off residue deposits collected on its interior surfaces over time.

If none of these solutions helps resolve your issue, check whether one or more parts in your carburetor may be damaged. If they are, it’s often easiest—if not cheapest—to replace them altogether rather than repairing them individually with replacement parts that might actually cost as much as an entirely new kit.

Here are other possible causes of your Stihl dying when hot.

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2. Fuel

Before proceeding, it’s important to check that your fuel and oil are fresh, at the correct ratio, and in a clean container. Cleanliness is especially important here: if any dirt or other contaminants get into the tank or lines, it could be enough to clog up the filter or jets.

You don’t want impurities in your system! Make sure you’re using high-quality two-stroke oil so that your trimmer will perform at peak efficiency. Once you’ve got the fuel situation squared away, inspect all of your connections for leaks. If any hoses aren’t tight enough, tighten them (but not too much).

Use a good flashlight to illuminate dark corners and check every inch of the hose thoroughly—even a pinhole leak can cause problems if left unaddressed. Ultimately, if your STIHL trimmer continues to die when hot after checking all these areas and performing maintenance as needed, check the Fuel Filter on top of the carburetor.

You can still remove it with needle-nose pliers or similar tools, soak it in some clean fuel overnight, and replace it with a new filter available at your local equipment dealer.

3. Air Filter

A dirty or clogged air filter can cause a drop in fuel delivery, essentially “choking out” the engine. Definitely, when this happens, it will automatically die.

When was the last time you took a look at your trimmer’s air filter? If it’s been a while, we recommend checking for dirt and clogs now. Clean or replace if necessary. Finally, check your air filter every few months to ensure that you spot any defects before arising.

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4. Spark Plug

A damaged or clogged spark plug can also be a culprit of this. The spark plug is an integral part of your trimmer’s engine that ignites the fuel that powers it. Without a good spark plug, your engine will be unable to run at full capacity, forcing it to shut down when it overheats.

To check the condition of your spark plug, pull the wire off and remove the old spark plug from its socket near the cylinder. If you spot a black residue or a carbon deposit on the spark plug, consider cleaning or replacing it.

You can use sandpaper and an abrasive pad to rub any gunk on the electrodes (the spark plug part with metal prongs). And in case you see some wear and tear on your electrode—or if cleaning doesn’t fix anything—your go-by choice should be a replacement.

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In short, if this is happening to you, try to identify what else is different about the day your trimmer dies. Was it hot? Were you working in a humid environment? Was the weather particularly cold or rainy?

We’re not recommending that you overheat your trimmer on purpose to replicate the issue, but we think this could lead you to identify what may have been causing the defect. Ultimately, to be safe, let your trimmer cool off if you notice it’s overheating during use. If possible, avoid running the trimmer for extended periods in extremely hot or dry conditions.

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