Why Are Lawn Mowers So Loud

Occasionally, we’ve all faced neighbors who wake early on weekends to spend hours mowing their lawn. Unfortunately, their lawnmowers are the noisiest examples known to man for unknown reasons.

If you have a lawnmower that throws out lots of lawnmower noise, you may be the neighbor they hate. In our guide, you can learn more about lawnmower engines and the lawnmower noise that comes out of them.

By the end, you’ll see why is your lawnmower louder than usual and what you can do to fix the issue with lawnmower mufflers. (Read Milwaukee String Trimmer Problems)

lawn mower green

Why Are Lawn Mowers So Annoying?

Mowers make so much noise because most engines use cheap primary absorptive mufflers on the exhaust system, which creates little gas flow restriction. Such a design is wonderful for powerful lawn mowing but terrible for noise.

Manufacturers in the lawn care industry could make a mower quieter, but they don’t want to compromise on pricing or engine power.

A voluntary noise target of 95dcb for mowers was established by the Outdoor Power Equipment Institute (OPEI) in 1974.

Mower Noise and Solutions

The engine creates most of the noise, but a spinning blade makes a startling amount like a helicopter’s rotors.

When you see an electric lawn mower, stop and listen. The blade cutting through air and grass is the primary source of the noise.

Mower noise arises from four primary causes; various treatments for excessive lawn mower noise are described below.

Mower Muffler

Exhaust/Muffler – Exhaust heat shields come loose, as does the baffle inside. To test, tap the muffler with a screwdriver handle and listen for the rattle.

Damaged Muffler

Check your muffler for damage; mower exhaust systems get hot and fracture and corrode, as well as make lots of sound.

Mowers cause a lot of vibration, so it’s a good idea to inspect your mower for loose parts frequently. Unfortunately, they also lack the noise reduction silencers of a car exhaust system.

Exhaust Gasket

Gaskets join the muffler and the engine. They form a seal, which breaks down, causing noise and smells. Gaskets are replaceable and can be done in a few minutes, reducing a mower’s loudness considerably. (Learn Why Does Grass Turn Yellow)

Blade

The blade noise generated by spinning blades compared to size is extremely loud. Blade tips cut through the air at speeds of over 200 miles per hour, and most lawn tractors feature two or three blades.

Bare Deck

Mower decks are freshly painted on the underside. The sound of debris flung against the deck echoes and creates a high noise level.

You may do this yourself by purchasing a spray-on bed liner from an auto parts store, which adds sound deadening and metal protection to your deck.

Also, try fastening sheets of self-adhesive bitumen car sound deadening material to the deck’s topside in a few areas. You can find these in the auto parts store, and they are effective in your mower, producing less noise.

lawn mower engine

Mower Engine

The engine makes a lot of noise. Besides the fan on top of the engine, you could have valves and rockers that are damaged.

You can help reduce noise by checking for valve lash. Fix this annually, and it will do a better job of keeping the noise level down and improving gas consumption.

Mower Engine Fan

Because most small engines are air-cooled, they require a fan to move cool air over the engine, and fans are noisy.

Another way to assist minimize noise is to use engine oil. Oil becomes thin as it ages, causing engine rattling. Your mower requires a tune-up at the start of each season and yard work.

Mower Body Rattles

The engine and blades will cause the body panels and deck connections to rattle and creak. Greasing all-metal deck arm contact areas with WD40 also helps minimize noise.

Check your hood and seat rubber stops and replace them as needed. Use a blade to cut old rubber hose for rattling hoods. (Read Fastest Growing Grass Seed for a Great Lawn)

Is There Such a Thing As A Quiet Lawn Mower?

There are two types of exhaust mufflers: absorptive and reflective. Most mowers have absorptive mufflers. Here’s the difference between muffler types.

Absorptive Mufflers

A simple absorptive muffler is not cleverly engineered and does not reduce noise well. Spark arresters are a mesh screen that collects sparks that may exit the engine.

This muffler restricts gas flow very little, which is why racing cars are extremely loud. Most lawnmower engines have this type of muffler.

Reflective Mufflers

Compared to the above, reflective mufflers would be super quiet lawn mower muffler. Their clever engineering kills noise. Sound waves are channeled via perforated baffles into resonating chambers where destructive interference eliminates some noise.

A particular acoustic suppression temperature resistant material (like rock-wool) is sandwiched between the chambers and the outer exhaust casing to suppress noise further.

Small mufflers don’t kill noise as much as a more oversized muffler. Hence the reason big cars have large mufflers.

Unfortunately, there is a downside, and that is flow restriction. Baffles and chambers cause restriction to gas flow, leading to back pressure, which reduces engine power.

Quiet Lawn Mower Mufflers

Some companies offer a modified muffler that should reduce exhaust noise even further. However, fitting a new muffler hoping you can kill all the noise doesn’t make it appear worthwhile, as it won’t reduce sound waves from the cutting blades.

electric mower

Go Electric

You can also get an electric mower instead of a gas-powered mower. Unfortunately, even though an electric motor is quieter than a gas engine, an electric mower is still rather loud.

Electric mowers can still be loud because the engine creates not all sounds.

The blades moving quickly provide a lot of the sounds a mower makes. The engine’s whirling blades operate as a blower pushes grass clippings in a bag.

Buy a Push Mower

You can acquire a push mower to solve the noise problem. The push mower blades are driven solely by your muscles and make very little noticeable noise.

Downsides are effort as the amount of energy required to turn the blades on this mower depends on the grass thickness.

Why Are Small Motors So Loud?

You may now wonder why lawn mower manufacturers do not make larger mufflers for their engines to reduce the loud roar. For starters, larger mufflers cost more. And manufacturers have understood that most people expect the noise of a lawn mower.

As a result, manufacturers do not invest in larger mufflers to reduce noise in lawn mowers because they would have to charge more than competitors for their lawnmowers.

Although the technology exists to reduce lawn mower noise, lawn mowers remain loud because of safety.

An extremely silent lawn mower may fool the user or a passer-by into believing it is not running. With blades capable of severing fingers and toes, everyone surrounding should be attentive when a lawn mower is running.

How Can I Make My Lawn Mower Quieter?

Here are other ways to ensure your mower is as quiet as possible.

Tighten Nuts Bolts and Screws

Loose components rattle more than they should, increasing noise coming from your mower. Before reassembling the body, check for any loose screws.

Fix or Replace Muffler

A muffler is a device attached to an exhaust pipe to reduce noise. Multiple chambers and insulation decrease noise while increasing engine pressure for efficiency.

Your lawn mower’s muffler will eventually fail because of normal wear and tear. In addition, sound can escape through fractures or crevices, reducing its efficacy.

The gasket seal between the exhaust and the muffler may also be damaged, allowing sound to escape.

Here’s some steps to check your muffler:

  1. When the lawn mower is entirely cool, unscrew the exhaust pipe.
  2. Remove the exhaust to access the muffler, which may be concealed within the lawn mower’s body.
  3. Remove the muffler totally by undoing the mounting bolts.
  4. Inspect it both inside and out for signs of damage. Cracks may only be visible on one side, so check both sides.
  5. Minor cracks can be filled with a product made expressly for this purpose.
  6. Replace it if there is any evidence of rust or cracks that appear deep.
  7. It’s also an excellent opportunity to replace the gasket.
  8. Before repairing the exhaust pipe, check it for damage.

If you need to replace the muffler, remember longer mufflers reduce noise levels more than shorter ones, so if you want a quiet lawn mower, this could be a smart option, yet you’ll lose power.

Change Engine Oil

To keep lawn mowers running smoothly, change the oil regularly. In the long run, engine oil can become clogged with particles. (Read Lawnmower Wont Stay Running – What To Do)

Change the oil every spring and potentially fall, depending on how often you mow.

Oil changes should be done soon after use as warm oil flows better.

  1. Place the lawnmower on a raised surface and tilt it.
  2. Put a pan beneath the oil fill cap.
  3. Remove the lid and drain the oil.
  4. Refill with fresh engine oil. Car brands are typically acceptable, but the owner’s manual will provide you with the correct information.

It is advisable to disconnect the spark plug before doing any work on your mower. Even when adding sound deadening material, you need to ensure your mower can’t start.

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