Why Your Hedge Trimmer is Smoking

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If you see smoke emerging from your hedge trimmer, turn it off now. This does not necessarily mean the machine is going to catch fire. However, it does indicate there is something wrong and needs immediate attention. There are many possible reasons and fixes in case this happens.

Dirt buildup, an overheated motor, wear and tear or an incorrect fuel mixture can cause a hedge trimmer to smoke. If the trimmer is battery powered, the connectors may be damaged.

The type of hedge trimmer you use determines what kind of smoke you could see, and how to fix it. There are two kinds of hedge trimmers: gas and electric. Battery powered hedge trimmers – both corded and cordless –are classified as electric.

There are three types of smoke you will see on a hedge trimmer: black, gray and white smoke.

  • Black and gray smoke appear in gas powered hedge trimmers.
  • White smoke can come from a gas, electric or battery powered machine.

How to Fix Black or Gray Smoke in a Hedge Trimmer

Smoke coming from a gas powered hedge trimmer will be gray or black. How you fix this depends on the cause.

The most common causes are:

  • Oil leakage
  • Dirty fuel system
  • Wrong fuel mix

When any of these occurs, a hedge trimmer will produce gray or black smoke. The first thing you should do is turn the machine off right away. Move the hedge trimmer away from any flammable materials.

Next, put on protective goggles, gloves and boots. Have a fire extinguisher nearby just in case as well as screwdrivers and wrenches to disassemble the engine if necessary. You might also need an engine cleaning kit. Now you can examine the trimmer closely and find out what is wrong with it.

Oil Leakage

Cause. Oil leaks usually come from a broken fuel line, so this is the first area you should check. Turn off the trimmer and let the engine cool down.

Fix. Examine the fuel lines for small holes, cracks or leaks. If there is a leak you will find oil all over it. Inspect the fittings if they are already worn out.

Damaged fuel lines have to be replaced. You can either buy and install these or take the hedge trimmer to a repair center. Make sure the replacements are compatible. If you have a Poulan Pro PR2322 hedge trimmer, the replacement must be designed for it.

Oil leakages can cause permanent damage or burst into flames. Find the source of the leak and replace the fuel lines as soon as possible.

Image Credit: Mark Hunter

Dirty Fuel System

Cause. Any engine that uses oil in its fuel mixture is going to get dirty with constant use. Fumes blacken and the carbon turns into soot, covering vital engine parts. The more dirt builds up, the harder it gets for the engine to run, forcing black or gray smoke out of the system.

Fix. Turn off the hedge trimmer and allow the engine to cool for a few minutes. Use a fuel system cleaning kit to remove the black soot. Follow the instructions provided with your kit. After cleaning, turn the hedge trimmer on again. It should run smoothly without any black smoke.

Wrong Fuel Mix

Cause. In some cases we get the mixture all wrong. This will make the hedge trimmer smoke and eventually stall. The good thing is this is easy to fix.

Fix. Check your owner’s manual for the correct gas and oil mixture. Most hedge trimmers use a 50:1 gas to oil ratio, but yours might be different.

Generally what you do is pour the gas first into a container followed by the oil. Cover the container and shake vigorously. Pour the mixture into the trimmer fuel tank. You will find more detailed instructions in your hedge trimmer owner’s manual.

How to Fix White Smoke in a Hedge Trimmer

White smoke can appear in gas and electric hedge trimmers because the cause is the same, an overheated motor.

Cause. The most likely reason for an overheated motor are:

  • Lack of lubrication
  • Worn out motor brushes
  • Battery connection problems

Worn Out Brushes

Cause. The commentator and the brushes generate friction, and over time this causes the motor brush to wear out. Because the motor brush performs an important role you have to repair this as soon as possible.

Fix. If the brushes are worn out, they have to be replaced. This will require you to remove the back plate and the motor, so if you are not comfortable doing this, take the hedge trimmer to a specialist.

Lack of Lubrication

Cause. Motors generate friction when they operate, and this will wear out its parts over time. If the motor is worn out from heavy use, it is going to overheat and produce smoke. This can cause serious damage or fry the electronics, so it must be fixed right away. We like the PlanetSafe AIM Hedge Trimmer Lubricant as it works very well with all kinds of trimmers.

Fix. Turn off the motor. Look at the blades and other parts if they are lubricated or not. If they are not lubricated, buy a motor engine lubricant and apply it to the blades and other parts. When you are done, turn the trimmer on again. If lubrication was the problem, the motor should be smoke-free now.

Battery Connection Issues

This is applicable to battery powered hedge trimmers only. Lack of lubrication and wear and tear can also affect these models. In addition to that you also have to look at the connection between the motor and battery.

Cause. The battery power supply connection can get damaged by water, misuse or wear out due to age. Cutting a lot of thick material including ivy can accelerate wear and tear.

When this happens it can short circuit the system. The battery will send an overflow of energy in the motor which results in overheating. This is what you see as white smoke coming out.

Fix. Shut the hedge trimmer down. Inspect the battery and motor connection. If it has corroded or damaged in any way, replace it immediately.

How to Prevent Hedge Trimmers from Smoking

The best way to prevent this is with proper maintenance and care. How you do this will depend on the type of hedge trimmer you have. This is a general overview of what you should do, but always check the owner’s manual for more details.

Electric and Battery Powered Hedge Trimmers

Electric and battery models should never be exposed to heavy downpour. Even if the product claims it is waterproof, there is always the risk of water getting into the battery compartment or electronics.

Battery overload. Battery powered hedge trimmers are not as powerful as electric or gas models. If you overload its system the motor will not be able to run. This will quickly result in overheating and all kinds of problems.

Safety guidelines. Anytime you use an electrical power tool, there is some risk involved. So take all necessary precautions.

  • Ensure the cord is properly connected.
  • Make sure the outlet is fully functioning.
  • Do not use a corded hedge trimmer in a wet, rainy environment.
  • Do not use old batteries, they could cause a lot of problems and damage some circuitry.

Gas Hedge Trimmers

Gas hedge trimmers have a lot of moving parts, and when dirt builds up can overwork the motor. The result could be black smoke everywhere, so regular cleaning and maintenance is essential. In particular, keep the following clean:

Air filters. Air filters keep dirt out of the engine, but if they collect too much debris, it will clog the engine. Without air an engine cannot run properly. If you see a lot of black smoke, it could be a sign of dirty air filter. Clean them regularly or if too worn out, just replace them.

Old oil. The fuel should be replaced on a regular basis, and never use old oil. If you are going to store the trimmer for months, empty the fuel tank. It is not a good idea to store any tool with a full tank because the oil will thicken and become unusable.

Running in extreme temperatures. Hedge trimmers can only run in certain conditions. The exact range is indicated in the manual. If it is too hot, the electronic circuits can fry or the motor can overheat. If the weather is too cold the fuel might not ignite.