Lawn Mower Muffler is Clogged: How to Tell What to Do
The muffler is one part of a gas mower that no one really pays attention to or appreciates until something goes wrong with it. You see, a muffler’s primary job is to reduce the amount of sound that your lawn mower produces. Whenever anyone asks “how can I make my lawn mower run quieter?” the #1 suggestion I would give is to check whether the muffler is damaged. If it is, replace it. If not, can you upgrade the current one to a better one? The muffler also has a second (and very important) role, which is to prevent exhaust sparks that could potentially ignite any dry debris that has made its way into the engine.
Some of the most common signs that a lawn mower muffler is clogged are a sudden increase in the amount of sound your mower produces, leaking exhaust fumes, a sputtering engine, and increased fuel usage.
Symptoms of a Clogged Lawn Mower Muffler
Before I get to explaining what you should do if your mower’s muffler is clogged or damaged, you first need to determine that it is in fact clogged or damaged. Here are the main signs to look out for.
Sudden Increase in Noise Output
As mentioned, the muffler’s primary role is to filter out a lot of the noise that is produced on each exhaust stroke of the engine. The hot gasses that are pushed out of the cylinder on this stroke can make quite a racket.
If you’ve been out mowing recently and suddenly noticed that the sound your mower was making jumped by a few levels, there’s a very good chance that the muffler could be clogged or otherwise damaged. This is not that uncommon after 2-3 seasons of regular use.
Engine Sputters and Stalls
The exhaust fumes are pushed out of your mower via the muffler. If the muffler is clogged, these fumes are not removed as effectively, and if they build up as the mower is running, it can make life very difficult for your engine. It’s not uncommon to see it running a lot rougher than normal and it may even stall.
This kind of symptom could also indicate a problem with your carburetor being dirty/blocked too, so if you clean the muffler out and still see this issue, that’d be the next thing to check.
Mower Using Fuel
Honestly, the increase in sound is the main thing to watch out for, as it’s something you will notice instantly. But another symptom of a clogged muffler that you’ll see over a longer period is that your mower starts to use more and more fuel to do the same amount of work.
This is because with the build-up of exhaust fumes, the engine is forced to work harder and harder, and that requires more fuel. So fixing a clogged lawn mower muffler is not only good for your hearing and the health of your mower, it’ll save you money on fuel costs too.
How to Fix a Clogged Lawn Mower Muffler
You definitely don’t want to continue to run your mower with a clogged muffler, as things will likely go from bad to worse. Running your mower without a muffler is also not an option (without it, exhaust sparks are possible….). That means you’re left with just two options; you clean the muffler or you replace it.
Cleaning a Lawn Mower Muffler
You need to take all of the usual safety precautions before you attempt to inspect and clean your muffler. Let the engine cool down completely and disconnect the spark plug before you do anything else.
Next, you want to remove the muffler from your mower. What this entails will depend on the mower you have, as mufflers can vary quite a bit. On my mower, there are two bolts that have to be removed and then it can be detached.
When a lawn mower muffler becomes clogged, it’s usually the spark arrestor that is coated in soot that has built up through normal use. That part needs to be cleaned or replaced, and to do so you’ll need to disassemble the muffler to get at it. Once you’ve removed the spark arrestor, you can either clean it with a solvent (make sure you submerge it and fully soak it) or take a propane torch, heat it up and you’ll be able to simply knock the soot off afterward.
I have to say that this is not the most straightforward mower maintenance job, and if you’re not confident in what you’re doing, you might want to take it to a pro to handle instead.
Replacing a Lawn Mower Muffler
Once you’ve detached the muffler as per the instructions above, it’s worth taking a minute or two to inspect it to see if it’s actually worth cleaning, or whether a replacement would be a better option.
Honda Lawn Mower Repair – How to Replace the Muffler
First thing first. Shake the muffler and see if you hear anything rattling around. If you do hear something, it’s likely that this is an internal baffle that has broken off and is now blocking the muffler’s airways. This needs to be removed. Sometimes it can be removed using a set of pliers, carefully and patiently extracting it through either the inlet or the outlet. If this is not possible, the only option might be to cut the muffler along the seam, remove the loose baffle and then weld the muffler shut again.
As well as the “rattle test”, watch out for signs of the following things in the outer casing of the muffler:
If you spot one or more of these things, and it looks as though your muffler has seen better days, it may be a better idea to retire it and source a new one. Just make sure it’s compatible with your mower and install it carefully. The difference will be immediately noticeable once you fire up your mower.
About Tom Greene
I’ve always had a keen interest in lawn care as long as I can remember. Friends used to call me the lawn mower guru (hence the site name), but I’m anything but. I just enjoy cutting my lawn and spending time outdoors. I also love the well-deserved doughnuts and coffee afterward!
Комментарии и мнения владельцев
I just bought a used 2015 42-in cut yard machine with a power more 420cc motor and it runs good but is loud as hell should I replace the muffler and how hard is it to do
Hi Butch! I can’t find a lot of specific information about that model online but given the style of mower it is, you shouldn’t have too much trouble getting to the muffler to inspect it. Is there any obvious outside damage? As mentioned in the article above, any cracks or rusted-out sections usually indicate that the muffler needs to be replaced. If the outside appears fine, the next step would be to disconnect the muffler so you can inspect it thoroughly. Taking a moment to give it a cursory clean, using the steps mentioned above, can help highlight any “hidden” damage. If there are any “loose” or “rattling” sounds, that’s an additional red flag. If you do decide to go ahead and replace the muffler, replacing it shouldn’t take more effort than getting the original muffler off of your mower. In many cases, there are a few parts that slot together and two or four bolts holding everything in place. In rare cases, there may be a weld, especially if the muffler had been repaired or modified in the past. My mower, for example, only has two bolts. Replacing the muffler, even on a slow day, will only take 30 to 40 minutes. If you do intend to DIY this task, always make sure to disconnect the battery before you start work and ensure that your mower is completely cool and on a solid surface. I hope this helps!
A neighbor gave me a used mower, a Honda push mower 5.5 engine, that he said runs well. But he tried to remove the muffler for some reason and sheared the bolts off. So it was free to me to fix. Project has not gone according to plan and likely won’t accept new bolts now. But, mower does run, and there’s a muffler shield box that covers the muffler. Is there an alternative I could place in that shield box that could act like a muffler that would be safe? Any ideas? Thanks.
Hi Robert, There isn’t much you can do with the shield box, as this will likely disrupt the exhaust flow from the cylinder head and potentially cause issues. The best option would be to use a bolt extractor tool (around 10 from Amazon). This tool will get the old bolt out that has a broken head. Then if the threads are damaged and the hole won’t take a new bolt, you can use a tap and die set (around 20 from Amazon). A tap-and-die set will recut the threads. I’ve used this method a few times on older equipment, and it works perfectly. Best of Luck! Tom.
Lawn Mower Muffler is Clogged: How to Tell What to Do
The muffler is one part of a gas mower that no one really pays attention to or appreciates until something goes wrong with it. You see, a muffler’s primary job is to reduce the amount of sound that your lawn mower produces. Whenever anyone asks “how can I make my lawn mower run quieter?” the #1 suggestion I would give is to check whether the muffler is damaged. If it is, replace it. If not, can you upgrade the current one to a better one? The muffler also has a second (and very important) role, which is to prevent exhaust sparks that could potentially ignite any dry debris that has made its way into the engine.
Some of the most common signs that a lawn mower muffler is clogged are a sudden increase in the amount of sound your mower produces, leaking exhaust fumes, a sputtering engine, and increased fuel usage.
Symptoms of a Clogged Lawn Mower Muffler
Before I get to explaining what you should do if your mower’s muffler is clogged or damaged, you first need to determine that it is in fact clogged or damaged. Here are the main signs to look out for.
Sudden Increase in Noise Output
As mentioned, the muffler’s primary role is to filter out a lot of the noise that is produced on each exhaust stroke of the engine. The hot gasses that are pushed out of the cylinder on this stroke can make quite a racket.
If you’ve been out mowing recently and suddenly noticed that the sound your mower was making jumped by a few levels, there’s a very good chance that the muffler could be clogged or otherwise damaged. This is not that uncommon after 2-3 seasons of regular use.
Engine Sputters and Stalls
The exhaust fumes are pushed out of your mower via the muffler. If the muffler is clogged, these fumes are not removed as effectively, and if they build up as the mower is running, it can make life very difficult for your engine. It’s not uncommon to see it running a lot rougher than normal and it may even stall.
This kind of symptom could also indicate a problem with your carburetor being dirty/blocked too, so if you clean the muffler out and still see this issue, that’d be the next thing to check.
Mower Using Fuel
Honestly, the increase in sound is the main thing to watch out for, as it’s something you will notice instantly. But another symptom of a clogged muffler that you’ll see over a longer period is that your mower starts to use more and more fuel to do the same amount of work.
This is because with the build-up of exhaust fumes, the engine is forced to work harder and harder, and that requires more fuel. So fixing a clogged lawn mower muffler is not only good for your hearing and the health of your mower, it’ll save you money on fuel costs too.
How to Fix a Clogged Lawn Mower Muffler
You definitely don’t want to continue to run your mower with a clogged muffler, as things will likely go from bad to worse. Running your mower without a muffler is also not an option (without it, exhaust sparks are possible….). That means you’re left with just two options; you clean the muffler or you replace it.
Cleaning a Lawn Mower Muffler
You need to take all of the usual safety precautions before you attempt to inspect and clean your muffler. Let the engine cool down completely and disconnect the spark plug before you do anything else.
Next, you want to remove the muffler from your mower. What this entails will depend on the mower you have, as mufflers can vary quite a bit. On my mower, there are two bolts that have to be removed and then it can be detached.
When a lawn mower muffler becomes clogged, it’s usually the spark arrestor that is coated in soot that has built up through normal use. That part needs to be cleaned or replaced, and to do so you’ll need to disassemble the muffler to get at it. Once you’ve removed the spark arrestor, you can either clean it with a solvent (make sure you submerge it and fully soak it) or take a propane torch, heat it up and you’ll be able to simply knock the soot off afterward.
I have to say that this is not the most straightforward mower maintenance job, and if you’re not confident in what you’re doing, you might want to take it to a pro to handle instead.
Replacing a Lawn Mower Muffler
Once you’ve detached the muffler as per the instructions above, it’s worth taking a minute or two to inspect it to see if it’s actually worth cleaning, or whether a replacement would be a better option.
Homemade Exhaust MUFFLER For Lawnmower ?
First thing first. Shake the muffler and see if you hear anything rattling around. If you do hear something, it’s likely that this is an internal baffle that has broken off and is now blocking the muffler’s airways. This needs to be removed. Sometimes it can be removed using a set of pliers, carefully and patiently extracting it through either the inlet or the outlet. If this is not possible, the only option might be to cut the muffler along the seam, remove the loose baffle and then weld the muffler shut again.
As well as the “rattle test”, watch out for signs of the following things in the outer casing of the muffler:
If you spot one or more of these things, and it looks as though your muffler has seen better days, it may be a better idea to retire it and source a new one. Just make sure it’s compatible with your mower and install it carefully. The difference will be immediately noticeable once you fire up your mower.
About Tom Greene
I’ve always had a keen interest in lawn care as long as I can remember. Friends used to call me the lawn mower guru (hence the site name), but I’m anything but. I just enjoy cutting my lawn and spending time outdoors. I also love the well-deserved doughnuts and coffee afterward!
Комментарии и мнения владельцев
I just bought a used 2015 42-in cut yard machine with a power more 420cc motor and it runs good but is loud as hell should I replace the muffler and how hard is it to do
Hi Butch! I can’t find a lot of specific information about that model online but given the style of mower it is, you shouldn’t have too much trouble getting to the muffler to inspect it. Is there any obvious outside damage? As mentioned in the article above, any cracks or rusted-out sections usually indicate that the muffler needs to be replaced. If the outside appears fine, the next step would be to disconnect the muffler so you can inspect it thoroughly. Taking a moment to give it a cursory clean, using the steps mentioned above, can help highlight any “hidden” damage. If there are any “loose” or “rattling” sounds, that’s an additional red flag. If you do decide to go ahead and replace the muffler, replacing it shouldn’t take more effort than getting the original muffler off of your mower. In many cases, there are a few parts that slot together and two or four bolts holding everything in place. In rare cases, there may be a weld, especially if the muffler had been repaired or modified in the past. My mower, for example, only has two bolts. Replacing the muffler, even on a slow day, will only take 30 to 40 minutes. If you do intend to DIY this task, always make sure to disconnect the battery before you start work and ensure that your mower is completely cool and on a solid surface. I hope this helps!
A neighbor gave me a used mower, a Honda push mower 5.5 engine, that he said runs well. But he tried to remove the muffler for some reason and sheared the bolts off. So it was free to me to fix. Project has not gone according to plan and likely won’t accept new bolts now. But, mower does run, and there’s a muffler shield box that covers the muffler. Is there an alternative I could place in that shield box that could act like a muffler that would be safe? Any ideas? Thanks.
Hi Robert, There isn’t much you can do with the shield box, as this will likely disrupt the exhaust flow from the cylinder head and potentially cause issues. The best option would be to use a bolt extractor tool (around 10 from Amazon). This tool will get the old bolt out that has a broken head. Then if the threads are damaged and the hole won’t take a new bolt, you can use a tap and die set (around 20 from Amazon). A tap-and-die set will recut the threads. I’ve used this method a few times on older equipment, and it works perfectly. Best of Luck! Tom.
A smoking lawn mower is never a good sign. Whether the smoke is blue, white, or black, here’s how to identity and address the issue without the help of a professional.
By Glenda Taylor and Bob Vila | Updated Sep 24, 2020 1:40 PM
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Q: Recently, my mower started billowing smoke when I powered it up, so I shut it off immediately. Why is my lawn mower smoking? And is it a fire hazard? I want to know how to proceed so I don’t harm the machine.
A: Your lawn mower can emit smoke for numerous reasons—many of which don’t require the services of an expert. A homeowner can usually identify the reason for a smoking lawn mower by gauging the color of the Cloud coming around the engine, then fix it accordingly before lasting damage occurs. Keep in mind that all mowers with internal combustion engines contain the same basic parts, but the configuration of those parts varies widely, depending on manufacturer and model. Consult your owner’s manual if you’re unsure how to access a specific part of your lawn mower’s engine.
White or blue smoke may indicate an oil spill on the engine.
If you’ve recently changed the oil in your mower and the engine is emitting white or blue smoke, it’s possible that some of the oil spilled onto the engine. Similarly, you could’ve spilled oil on the engine by mowing on a slope greater than 15 degrees or tipping the mower on its side. The smoke may look disconcerting, but it’s completely harmless. Solve the problem by restarting the mower and allowing the spilled oil to burn off. If you tip the mower often for cleaning or maintenance, check your owner’s manual to determine the best way to reduce the risk of oil leaks.
An overfull oil reservoir may also cause white or blue smoke.
Ensure you didn’t overfill the mower by checking the oil level with the dipstick located on the reservoir. To do this, remove the dipstick cap, wipe off the stick with a rag, and reinsert it into the reservoir. Then remove the dipstick once again and determine the oil level in comparison to the recommended “fill” line on the stick. If the level is too high, drain the oil (consult your owner’s manual for instructions), then refill the reservoir with it. Start checking the oil level with the dipstick after you’ve added about ¾ of the amount recommended in the manual. Continue to add small amounts of oil until the level matches the recommended “fill” line. Also note that using the wrong grade of engine oil may cause blue or white smoke. Consult the owner’s manual for the exact type of oil recommended for your mower.
Black smoke may indicate that the mower is “running rich,” or burning too much gasoline.
Your lawn mower’s carburetor regulates the ratio of gasoline to air mixture. If the carburetor isn’t getting enough air, the mixture has a higher percentage of gasoline, which can create black exhaust smoke. It’s possible that a dirty or clogged air filter is preventing sufficient airflow into the carburetor. Try replacing the air filter. (Note: air filters vary by mower model; view example air filter on Amazon.) Next, run your lawn mower for a few minutes. If the black smoke still appears, the carburetor might need to be adjusted in order to increase airflow. Either take the mower to a professional or adjust the carburetor yourself with instructions in your owner’s manual.
Take your mower to a repair shop if necessary.
If the previous steps don’t correct blue or white smoke, your mower could have a more serious problem, such as an air leak in the crankshaft (the cast iron or cast aluminum case that protects the moving parts of a mower’s engine). Continuing blue or white smoke could also indicate that some of the engine’s components or seals are worn out and need replacement. Similarly, if black smoking still persists after you’ve replaced the air filter and adjusted the carburetor, you could be facing a more serious mechanical issue. All of these problems require the help of a professional. If your mower is still under warranty, check with the manufacturer for the location of the nearest servicing dealer; problems stemming from a factory defect or poor workmanship may garner free repairs. If your mower is not covered under warranty, a reputable small-engine repair shop should also be sufficient to get the job done.
Why Does My Honda Lawn Mower Backfire?
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When it comes to lawn mowers, Honda is among the most popular brands in the business. Occasionally during use, you might find that your Honda lawn mower backfires. A backfire is a pop or loud boom that occurs when gasoline ignites outside the engine’s combustion chamber; so, what causes a Honda lawn mower to backfire?
A lawn mower backfires when burning fuel enters the exhaust or the engine. This happens when s of unspent gasoline enter the engine or exhaust system before the valves close. Backfires occur due to Rapid deceleration, faulty components, and even incorrect fuel blend, among other causes.
Want to know more about why your Honda lawn mower is backfiring? Read on as we discuss proven ways to fix a backfiring lawn mower.
Causes of Engine Backfires in Lawn Mowers
Below are some of the leading causes of backfiring in Honda lawn mowers.
Decelerating Too Fast
Lawn mower backfires mostly occur during Rapid deceleration when the engine attempts to align its timing with the lowered throttle. In most cases, this tends to lead to excessive air in the mix, which in turn creates a lean blend. The lean blend is consequently forced into the lawn mower’s exhaust system, where it makes the infamous pop sound when it combusts.
Slowing down a small engine should be gradual. Therefore, if your Honda lawn mower is backfiring when you’re looking to shut it off, chances are you’re decelerating too fast. The engine speed increases when using a lawn mower, and shutting it abruptly means the engine could pump some stray gas into the muffler, which could lead to combustion.
To prevent backfires when turning off your Honda lawn mower, reduce the mowing speed gradually, and allow the motor to idle for roughly 20 seconds before turning it off.
Fuel Blend
Fuel blend is a crucial aspect to consider when dealing with small engines. You’ll find that some gasoline contains ethanol or alcohol as part of the fuel blend, which can prove troublesome over time. Most Honda lawn mowers struggle to burn this blend effectively, which often results in power loss and occasional backfires.
Since lawn mowers are designed to handle specific blends of gasoline, using a wrong blend can lead to system imbalances. Due to this, it is advisable to use gas containing zero alcohol levels. If zero-alcohol blends are hard to come by, go for blends that contain low levels of alcohol.
Copyright protected content owner: ReadyToDIY.com and was initially posted on 2020-08-14.
Water Contamination
Water is another major cause of backfiring and loss of power in mowers. To remove water from your Honda lawn mower, you’ll need to start by removing the spark plug. Afterward, carefully remove the carburetor and clean it thoroughly. You should also check on the combustion chamber’s moisture levels before adding some fresh engine oil to coat the walls of the piston chamber.
Water contamination is a serious problem that, if not addressed early enough, can lead to long term damage to fuel lines, the tank, and carburetor.
Lean Carburetor
The carburetor is crucial to the functioning of a lawn mower as it regulates the volume of gas and air required for combustion. The balance must be perfect for proper combustion. While some Honda carburetors come with an electrical solenoid to control fuel flow, most come with two adjustment screws that are usually mounted on the exterior. One screw is for controlling the mix, while the other is for idle adjustments.
If the carburetor produces a lean mix, chances as the lawn mower will backfire during deceleration or even during normal operation. The good news is that carburetors are easily adjustable. However, consulting with a professional is advisable if it’s your first time attempting to adjust your Honda lawn mower’s carburetor.
Dysfunctional Valves
Valves are essential parts of a lawn mower that need to function correctly for successful outcomes. The valves help to seal off the firing chamber or cylinder of a small engine. One valve allows air and gas to make way to the cylinder while the other opens to allow the exit of exhaust gases from the cylinder.
Copyright article owner is ReadyToDIY.com for this article. This post was first published on 2020-08-14.
If one of the valves malfunctions (even for a second), then the lawn mower will backfire. But fixing valves on your own isn’t recommended since they are internal parts of your Honda mower. Consider outsourcing the valve repair job to experienced service professionals.
Damaged Spark Plug
A damaged or worn out spark plug will create a weak spark that might fail to ignite the cylinder. This means that instead of igniting in the cylinder, the fuel might ignite once it reaches the exhaust muffler, which results in a backfire.
Also, an incorrectly set gap between the spark plug’s electrodes tends to result in weak sparks that make the mower unreliable. Replacing the spark is necessary if your Honda lawn mower is backfiring as a result of weak sparks.
Poor Airflow in the Engine Area
When the engine runs at a higher than normal temperature, your Honda lawn mower might gradually start to backfire. This explains why most lawn mowers require enough space in the engine housing to allow for adequate airflow.
Your engine needs enough air circulation for it to cool. Therefore, besides turning off the engine and allowing it to rest, you can consider modifying the engine’s housing to improve air circulation inside the mower.
Damage to Internal Components
Your Honda lawn mower shouldn’t backfire when starting, and if it does, then one or two components are not functioning correctly. You’ll find that a broken flywheel often leads to stuttering or backfiring when attempting to start a mower.
Luckily, the more sensitive areas of a lawn mower, such as the crankshaft, are usually surrounded by their inexpensive counterparts that cost a lot less to repair. Therefore, if your Honda lawn mower is backfiring when starting, you’ll need to call in a professional to identify and repair the damaged components.
How to Keep Your Honda Lawn Mower From Backfiring
Avoid Cutting Wet or Damp Grass
Mowing the lawn when the grass is wet or damp can damage your mower, consequently leading to long term problems. As mentioned earlier, you should remove water once you suspect either the tank or carburetor has been contaminated.
Read the User Manual Before Use
Lawn mowers function differently. Take enough time to read the instructions before putting your new Honda lawn mower to good use. Generalizing the function of different brands of lawn mowers can lead to backfiring or malfunctioning when wrongly used.
Clear Debris Before Mowing
Large stones, toys, twigs, and branches might damage your Honda lawn mower. Although most mowers come with adequate safety-enhancing features, exposing them to extra hard surfaces and conditions might lead to backfiring and even total damage.
Check the Fuel Blend
Gasoline with high alcohol concentration is more likely to lead to backfiring compared to using pure gasoline. Go for fuels with little to no alcohol concentrations to eliminate the chances of backfiring due to fuel.
Final Thoughts
While it’s normal for lawn mowers to backfire every once in a while, you should always take your time to determine the cause of backfiring. Factors such as fuel blend and water contamination can gradually damage your yard-maintenance device, leading to serious defects.
Although backfires aren’t dangerous to the engine or users, the large pop noises can be annoying. And to prevent a backfire when you’re done mowing, be sure to turn off the mower gradually, specifically 15-20 seconds after the blades have come to a halt.
Remember, since backfires tend to indicate underlying issues with your mower, you should consider reaching out to an expert if you can’t determine the cause(s) of backfires.
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ReadyToDIY is the owner of this article. This post was published on 2020-08-14.