Lawnmowers have a reputation for being loud machines, but over time, a lawnmower can get louder than usual to the point where it becomes difficult to use it. While we can’t do much about the engine’s normal sound, some noises, such as grinding sounds, squeaking, and knocking, are not normal and need to be fixed. Some common reasons why your lawnmower is louder than usual include:
- Your blade assembly might be loose, which creates a loud rattling noise
- The build-up of grass and debris under the deck of the mower and on the blade can produce a loud clunking sound
- The damaged or rusted muffler can increase the sound of the engine
- Not changing the engine oil regularly can cause a knocking sound from the engine
Any unusual sound coming from your lawnmower should be looked into immediately. If your lawnmower is running louder than usual, it can also cause permanent damage to your mower and reduce its life if you ignore the noises. That is why we will tell you about the causes of why your lawnmower has gotten loud and how you can fix them.
- 1 ● Loose blade assembly
- 2 ● Grass and debris buildup under the deck
- 3 ● Damaged or worn out muffler
- 4 ● Not changing the engine oil frequently
- 5 How loud is too loud for a lawn mower?
- 6 Final remarks
● Loose blade assembly
One of the most commonly experienced noises from a lawnmower is a loud rattling sound resulting from a loose blade assembly. If the blade assembly is loose, it will move around during startup and keep rattling as the lawnmower runs. Sometimes the blade itself can be bent or damaged, which can cause a lot of noise and put a lot of strain on the drive shaft itself.
Fixing a loose blade assembly
You can fix a loud blade assembly yourself by following these steps below:
- Step 1: Take precautionary measures: Disconnect the spark plug wire before you tip the lawnmower on its side and ensure that all power switches are in the off position. This precaution will ensure that the mower doesn’t start up accidentally when looking at the blade assembly.
- Step 2: Check the bolt tightness: Tip the mower on its side, get a wrench, and see if the bolt holding the blade is tightened up or not. If the bolt feels loose, get a piece of wood to jam the blade in place and turn the bolt clockwise until it is tight.
Note: If your blade assembly is not loose and the bolt is tight, but you still hear vibrations and rattling from underneath the lawnmower’s deck, then chances are your lawnmower’s blade is the source of the noise. If the blade is out of balance (one side is lighter than the other), you can use a mower blade balancer to balance both sides of the blade, or if the blade is severely bent or damaged, you might have to replace it.
● Grass and debris buildup under the deck
If you mow wet grass quite often, then grass and debris will build up underneath the deck and the blade itself over time. This leaves little to no room for grass to circulate as most of the deck’s space gets taken over by debris buildup. This grass buildup will deflect the blade as it spins, and a clunking sound can be heard from under the deck.
Getting rid of debris from the deck of the mower
You can use a pressure washer to clean the deck of most lawnmowers, but you should refer to the user manual which came with your mower to confirm if you can use water to clean the deck. You can follow these simple steps to remove debris from your mower’s deck properly:
- Step 1: Clean the debris by using the right method: Unplug the spark plug wire and tip the mower on its side to access the deck. If your mower’s user manual allows you to use water on the deck, use a power washer to loosen up the grass and debris buildup from the deck. If you can’t use water to remove the debris, you can use a scraping tool to remove built-up grass or compressed air to blow away the debris. Whatever method you use, make sure to get rid of all the debris from the deck and your mower’s blade.
- Step 2: Apply WD-40 to the deck: After cleaning the debris, apply some WD-40 to the mower deck to prevent debris from building up again.
Note: Ensure you don’t apply too much WD-40 because the excess lubricant will drip off onto your lawn’s grass.
● Damaged or worn out muffler
A muffler is used to suppress the engine exhaust’s sound, reducing the engine noise significantly. But if the muffler gets damaged or is not properly sealed with the engine, the noise will not be suppressed properly, and you will hear a lot more noise coming from your mower’s engine. Sometimes, the muffler’s damage may be visible in the form of holes or cracks, while other times, the muffler may not fit properly with the engine outlet. Luckily most lawnmowers come with easy-to-remove mufflers that are relatively cheap to replace and install. You can buy a decent muffler for your lawnmower for between $20 to $40, and replacing a worn-out muffler should reduce engine noise significantly.
Fixing a damaged lawnmower muffler
Since lawnmower mufflers are not too expensive, it is recommended to replace the muffler instead of trying to fix it because even if you put some sealant on the hole or crack, it will come off in no time. Replacing your lawnmower’s muffler is a pretty straightforward task, and it can be done in a few easy steps.
- Step 1: Let the engine cool: Before starting the muffler replacement process, ensure the engine is not hot. If you have just used the mower, it is wise to wait a few hours before replacing the muffler. Wear a pair of work gloves for protection and turn the muffler counterclockwise to make it loose. Keep turning the muffler until it comes off.
Note: Sometimes, the muffler may be stuck due to rust, and to unscrew it, you will need a pipe wrench to get it unstuck. Most lawnmowers can be removed by simply turning them, but some mowers have an exhaust pipe with the muffler attached to the pipe’s end. If the exhaust pipe itself is damaged, you will have to replace it as well, which is a bit difficult compared to removing the muffler, and you might need professional help to avoid damaging your mower’s engine.
- Step 2: Buy the new muffler: Don’t throw away the damaged muffler just yet because you will need to buy a matching muffler that fits your lawnmower. So take the old muffler to the store to find a similar new muffler to install on your mower.
- Step 3: Install the new muffler: Putting the muffler back on is as simple as taking it off. All you have to do is put the threaded end of the muffler into the engine’s exhaust outlet and turn it clockwise until it is nice and tight. With a new muffler installed, your lawnmower should run quieter now.
● Not changing the engine oil frequently
While lawnmower engines are small, they still require regular oil changes every 30 to 40 hours of use or twice a year. Engine oil lubricates different moving parts of your lawnmower’s engine; over time, heat and friction can burn up the oil. After a certain time, the engine oil loses its ability to lubricate the engine properly. This causes the engine’s moving parts to rub against each other, making the lawnmower louder than usual when running, and a loud knocking sound can be heard coming from the engine. Luckily some lawnmowers have a built-in low engine oil alert, which lets you know when to change the engine oil, but even if you have a mower that doesn’t have a low engine oil alert, you can easily check and change the engine oil using the method explained below:
Changing engine oil
You should change the engine oil of a lawnmower at the start of every mowing season and again during the mowing season if the mower engine starts getting noisy and the oil turns dark in color.
- Step 1: Warm the engine up: You will want to warm up the lawnmower’s engine before changing its oil because warm oil flows out easily.
- Step 2: Place an oil container: Place a pan underneath the oil fill to catch the old oil and tip the mower to its side so that the oil fill cap points downwards with the pan directly under it.
- Step 3: Drain the old oil: Now remove the oil fill cap with the lawnmower tipped to its side and let the oil drain out for a minute or two.
- Step 4: Add fresh oil: Pour fresh engine oil into the mower’s engine and make sure to pour the correct amount of oil into the engine.
Note: You can find the correct type of oil and the correct quantity of oil in the owner’s manual of the mower.
How loud is too loud for a lawn mower?
If your lawn mower is louder than usual, it will cause a lot of distraction in your society, especially if you’re mowing early morning, late evening, or weekend. If you ignore these sounds and allow yourself and your neighbors to be exposed to them for several hours, it will cause permanent hearing loss by killing some important cells inside your ears. The decibels of sound varies by the fuel, type, model, and size of your lawn mower.
Remember that humans talk at just 60 decibels and ensure that the surrounding sounds don’t exceed 85 decibels, which is harmful. I recommend installing sound measuring applications on your smartphone or using a manual sound meter. As soon as you notice that the sound of your lawn mower is over 85 decibels and you are exposed to it for over 90 minutes, it would be best if you use hearing protection. Personally, I would always wear it, also when the duration is much shorter.
If you find it challenging to use a decibel meter on your phone and don’t have a sound meter, you can also use this rule of thumb: if your lawnmower sound is such that you have to yell to talk to someone nearby, it is too loud.
Let me now categorize the average sound level of different lawn mowers based on the fuel that they run on:
- Gas-powered lawn mower: The normal sound of a gas-powered lawn mower is 85 decibels, so you must use properly licensed hearing protection if you plan to use it for a couple of hours or if you are working near a moving one.
- Electrical lawn mower: The average sound of a properly functioning and well-cared electrical lawn mower is just 75 decibels which is quite comfortable to use as compared to the gas-powered one. In the opinion of medical professionals, this level of sound will not harm your hearing.
- Riding lawn mower: This is the loudest type of lawn mower, producing over 100 decibels of sound, so exposure to it without proper hearing protection for just four to nine minutes can cause permanent hearing loss.
- Tractor: It produces 92 decibels, so you must not use it without hearing protection for 90 minutes. And if you are continuously around such a noise for eight hours, even with hearing protection, you are still at risk.
- Unpowered manual reel mower: It has no engine, so it makes minimum noise and is the safest option for those at a higher risk of hearing loss.
Ear muffs, canal caps, custom-designed ear plugs, reusable ear plugs, and roll-down foam ear plugs are all the best and most reliable ear protection gear, but make sure that they are produced by licensed manufacturers.
An alternative could be a suitable over-the-ear headset, which you can use to listen to music or a podcast while using your lawnmower.
Many states in the USA forbid homeowners to operate noisy lawn equipment before 7 a.m. or 8 a.m. and after 8 p.m. on weekdays and weekends. You will face penalties and other legal issues if you ignore these rules. Ask your neighbors if your task is unavoidable and discuss the time suitable to carry out such tasks.
With some care and proper maintenance, you can get rid of loud noises common in lawnmowers. Now that you know the possible causes, you can perform the necessary fixes by yourself. If anything is ambiguous or the noise persists, it is always better to consult a professional.