Why is My Lawn Mower Making a Noise (Grinding, Whining, Chugging, & Tattling)?

Why is my lawn mower making a grinding noise?

The reason your lawn mower is making a grinding noise is because of worn bearings that needs to be lubricated, or a bent crankshafts that can happen if the blade accidentally hits a stone. A broken plastic gear starter can also cause your lawn mower to make a grinding noise.

Worn bearings

The lawnmower system consists of a mandrel with two bearings, which, when not lubricated, can make a grinding sound. The mandrel is a steel cylinder that holds the lawn mowers deck cutting blades.

Bent crankshaft

Your Lawnmower’s crankshaft can bend while mowing if the blade accidentally catches a stone or a stump in tall grasses. A bent crankshaft can make your lawn make a grinding noise as the crankshaft acts as a bridge between the piston and the flywheel.

Broken plastic starter gear

When the plastic starter gear of your lawn mower is broken, your lawn mower might stop in the middle of the mowing process and die. When you restart it again, it can make a loud grinding noise. Grinding noises notify you that your lawn mower’s plastic gear is broken.

How to fix a lawn mower that is making a grinding noise?

To fix a lawnmower that makes grinding sounds, you can replace the mandrel assembly if it’s worn, replace the crankshaft if it’s bent, or replace the ground plastic gear starter.

Replace worn mandrel assembly

You should check the mandrel bearings immediately when your lawn mower starts making a grinding noise. If the bearings are worn, replace the mandrel assembly. The mandrel assembly includes the blade shaft and bearings. Follow the steps below to replace worn mandrel assembly.

Park your lawn mower on level ground and use the parking brakes to prevent it from moving. Then turn the ignition switch off.
Put on a working glove to protect your hand during the maintenance practice.
Disconnect the spark plug wire to prevent the engine from starting unintentionally.
Remove the lawn mower deck.
Put a wood block between the blade and the lawn mower deck to prevent the cutting blade from moving.
Next, remove the pulley mounting nut and detach the pulley, then pull out the wood, flip the lawn mower deck over, and put the wood block back in place.
Loosen the nuts holding the blade with an appropriate wrench and pull off the cutting blade.
Remove the wood block and flip the deck upright.
Loosen the bolt holding the mandrel with an appropriate wrench and pull the mandrel out from under the deck.
Go to the nearby local auto store and purchase a new mandrel. It costs about $27.
Install the new mandrel following the procedure outlined in the owner’s manual.
Reinstall the mower, reconnect the spark plug and lower your lawn mower back upright.

Replace bent crankshaft

You have to replace a bent crankshaft of your lawn mower to prevent your lawn mower from making grinding noises. Follow the steps below to straighten your lawn mower crankshaft.

Prepare your Lawnmower by draining the fuel from the fuel tank and the oil from the motor to prevent fuel and oil from spilling.
Disconnect and remove the air filter and the fuel tank.
Remove the engine cables and throttle cable out using a Philips-head screw.
Remove the metal casing on the engine and disconnect the spark plug wire.
Strikes the starter clutch with a rubber hammer carefully until it’s loosened, then remove the clutch.
Remove the flywheel and the housing by loosening the bolt and holding it with a flat blade screwdriver.
Tap the flywheel with a rubber hammer and gently pry loose with the screwdriver blade.
Pull off the shear pin of the crankshaft and remove the blade using a wrench.
Return your lawn mower upright position and disconnect the engine’s bolt. Put out the motor and set it aside.
Locate the valve spring cover and disconnect the screw holding the cover in place. Place the valve spring compressor tool on the valve spring, and then push it down on the spring. Move the metal washer up and off while the spring is compressed, and carefully let go of the spring. Repeat on the other side with the second valve spring.
Slide the case of the blade and pull out the camshaft gear. Push down on the tabs where the rods are connected and unscrew the bolts to remove the rod end cap.
Push down on the connecting rod and move the rod up until the cylinder piston moves to the top, then turn the crankshaft slowly and move the crankshaft off the engine.
Now, straighten the bent crankshaft. Place it on a hard surface, and then insert a heavy pipe over the bent section of the shaft.
Hammer the pipe over the shaft two to three times, and then remove the pipe. Check the straightness of the shaft and repeat the hammering process until the shaft straightens.
Reverse the disassembly process to put your mower back together.

Replace ground plastic starter gear.

When the plastic starter gear of your lawn mower is ground, you will have to replace it. Follow the steps below to replace your lawn mower’s ground plastic starter gear.

Park your lawn mower on level ground and engage the parking brake. Then turn off the ignition key.
Remove the spark plug wire and disconnect the battery cables.
Remove the red battery cable at the bottom of the starter by turning the nut and holding it using a pair of pliers.
Next, pull the solenoid wire off the starter. A solenoid is a small wire that connects to the starter’s top.
Remove the oil dipstick tube by loosening the nut that connects it to the engine using an adjustable wrench.
Hold the starter with one hand and remove the top two bolts mounting it to the engine using an adjustable wrench. Then pull the old starter out of the engine.
Purchase a new starter from your nearby local auto shop—a new starter costs around $ 58.
Align the bolt holes on the new starter and tighten them with an adjustable wrench.
Reconnect the red battery cable and tighten it using a pair of pliers.
Reattach the spark plug cable.

Why is my lawn mower making a whining noise?

The reason your lawn mower is making a whining noise is because of lack of lubrication that can happen if the engine oil level is low, or a worn starter that can be detected if the starter doesn’t engage the flywheel. A baffling belt that can happen if the belt is loose or damaged can also cause your lawn mower to make a whining noise.

Lack of lubrication

A low level of engine oil can suddenly make your engine protest with a whining noise before it dies because of a lack of proper lubrication.

Worn starter

When your lawn mower starter is worn, the starter will spin, but it won’t engage the flywheel causing it to make whining noises as the starter is sticking or spinning backward.

Baffling belts

When the belts powering your lawn mower become loose or damaged, it can cause a whining noise.

How to fix a lawn mower making a whining noise?

To fix a lawn mower that makes whining sounds, you can refill the engine oil if its level is low, replace the starter if it’s worn, or replace the belt if it’s damaged.

Refill the engine oil

Check the engine oil level. If it’s low, fill the reservoir to the fill line. Follow the steps below to refill the engine oil.

Prepare your lawn mower by placing it on level ground and engaging the parking brakes.
Extract the dipstick, wipe it, and insert it back into the fill opening. Remove it to check the oil level and cleanliness of the oil. If the oil appears clean but is low, add the oil.
Insert the funnel’s nozzle into the fill opening, and then pour a small amount of new motor oil (recommended by the manufacturer) into your lawn mower crankcase to the fill line.
Screw the fill plug back into the crankcase. Now, you are ready to mower your lawn.

Replace worn starter

When your lawn mower starter is not engaging the flywheel, you will have to replace it as it’s worn. Follow the steps below to replace a worn starter of your lawn mower.

Park your lawn mower on level ground and engage the parking brake. Then turn off the ignition key.
Remove the spark plug wire and disconnect the battery cables.
Remove the red battery cable at the bottom of the starter by turning the nut and holding it using a pair of pliers.
Next, pull the solenoid wire off the starter. A solenoid is a small wire that connects to the starter’s top.
Remove the oil dipstick tube by loosening the nut that connects it to the engine using an adjustable wrench.
Hold the starter with one hand and remove the top two bolts mounting it to the engine using an adjustable wrench. Then pull the old starter out of the engine.
Purchase a new starter from your nearby local auto shop—a new starter costs around $ 58.
Align the bolt holes on the new starter and tighten them with an adjustable wrench.
Reconnect the red battery cable and tighten it using a pair of pliers.
Reattach the spark plug cable.

Replace worn belt

Examine the belt of your lawn mower. If worn, frayed, or broken, replace it to restore the mower to working order. Follow the steps below to replace your lawn mower’s worn drive belt.

Place your lawn mower on level ground and engage the parking brakes to prevent it from moving while you’re working.
Detach the spark plug wire to prevent it from starting during lawn mower maintenance.
Remove the cutting deck and the battery.
Loosen the large nut holding the transaxle pulley.
Disconnect the spring from the anchor bolt on the left side of the lawn mower using a spring puller to relieve tension on the upper drive belt.
Remove the upper drive belt and the mower belt guide.
Take the belt off the variable pulley.
Remove the belt keeper that surrounds the engine pulley.
Remove the belt holding the crankshaft pulley using a wrench. As you remove the engine pulley, note the position of each part for reassembly.
Remove the lower drive belt from your lawn mower by pulling it.
Install the new drive belts (lower and upper drive belts).
Reverse the disassembly process to put your lawn mower back together.

Why is my lawn mower making a chugging noise?

The reason your lawn mower is making a chugging noise is because of old or wrong fuel that needs to be drained, a dirty air or fuel filter that is clogged with dirt and debris. A dirty lawn mower deck can also cause your lawn mower to make a chugging noise.

Old or wrong fuel

The gas you purchase at your local gas station can be wrong as it contains about 10% ethanol. Its advantage is that it is cheaper than pure gasoline, but the disadvantage is that it’s of low quality. The ethanol in the gas burns rapidly and can potentially melt the plastic parts, causing your lawn mower to make a chugging noise.

Moreover, the gas will go wrong if your lawn mower stays in your garage for a couple of months, causing your lawn mower to make a chugging noise when you start it after that long storage period.

Clogged or dirty air filters

Check your lawn mowers air filter regularly as it gets clogged with time after repeated mowing. The air filter traps dirt and debris, preventing them from reaching the engine during mowing. If the air cleaner is dirty, the engine is denied enough air, causing your lawn mower to make a chugging noise.

The air filter is either a paper or a form filter. The foam air filters can be removed and cleaned in warm, soapy water, whereas the paper filer needs to be replaced.

Dirty fuel filters

You need to check your fuel filters regularly. The fuel filters protect the engine’s critical parts by screening out contaminants such as dirt, dust, debris, and rust particles from the fuel. You, therefore, need to clean your fuel filters regularly as they get clogged with time, interrupting a regular flow of fuel and causing a lack of enough fuel needed for the engine’s proper functioning.

This imbalance of fuel in the engine can cause your lawn mower to make a chugging noise.

A dirty mower deck

While mowing tall grasses, they get trapped and cake on the mower deck, causing your Lawnmower to make a chugging noise. Check the underside of your lawn mower; you will see excess grass.

How to fix a lawn mower that is making a chugging noise?

To fix a lawn mower that makes chugging sounds, you can use ethanol free gas and drain the fuel if it’s old, clean or replace the air filter if it’s dirty or worn respectively, clean the fuel filter if it’s clogged or clean the dirty mower deck.

Use ethanol-free gas and drain the old fuel.

If you have been using ethanol gas, you should start using pure gasoline. It would burn cleaner and enable your lawn mower to start on the first pull and roar smoothly.

Also, you can drain the old fuel if your lawn mower stays in your garage for a couple of months without being started. Follow the steps below to remove old gasoline from the gas tank of your lawn mower.

Collect the required tools, which include a gas-resistant drain container, two plastic horses (a short and long one), which are easily found at many stores selling lawn mowers supplies. It would be best if you also had a rag at hand.
Park your lawn mower and use the parking brakes to prevent it from moving.
Disconnect the spark plug cable to prevent the engine from starting unintentionally. Then turn the ignition off and open the fuel cap.
Place the empty container next to the lawn mower’s gas tank on the ground. Ensure the empty container collecting the gas is lower than the tank’s bottom for perfect siphoning to happen.
Insert the longer plastic horse deep enough into the mower’s gas tank to be immersed entirely in the petrol. Then place the opposite end of the longer container into the drain container.
Place the shorter plastic horse some inches into the gas tank such that the two tubes lie side by side. However, the shorter tube should remain suspended and not touch the fuel inside the tank. Its function is to develop a channel between the tank and the atmosphere.
After that, the next step is to seal the fuel cap, through which the horses were inserted, to ensure that air flows inside only through the shorter tube, thus helping develop an air pressure gradient that pushes out the liquid fuel. You can use a piece of old wet rag to seal the connection. The wet rag is used as it sticks and seals properly.
Now, on the open end of the plastic horse, you can blow hard to push the air in the tank. You can also use an air compressor to make work easier. You will notice that fuel starts flowing through the plastic tube after several blows, though some will remain.
To remove the remaining gas, run your lawn mower. Take the plastic tubes out of the opening, close the tank and collecting container, and store the fuel well for future use. Reattach the spark plug and turn on the ignition.
Take the lawn mower out of the garage and run it till it dies. You will now have fully drained all the gas.

Clean or replace dirty air filters

You have to check the air filters regularly. The air filter traps dust, dirt, grass, and sand, preventing them from reaching the engine as the air filter gets clogged. Paper air filters must be replaced, whereas you can generally clean foam air filters. Follow the steps below to clean a form air filter.

Remove the air filter cover.
Separate the form air filter from the plastic cage.
Place the form filter in a basin with soapy water and scrub the dirt while squeezing.
Rinse it with clean water.
Let it dry under the sun.
Pour the oil evenly over the filter.
Reinstall the air filter and the cover.

Follow the steps below to replace the paper air filter.

Loosen the screw holding the cover using a screwdriver.
Carefully remove the cover, ensuring the screws holding the cover in place don’t fall off.
Carefully remove the paper filter from the air filter housing and dispose of it carefully.
Install the new paper air filter and fix it properly in the air filter housing.
Reattach the cover and tighten the loose screw holding the cover using a screwdriver.

Clean fuel filters

You need to clean the air filter regularly, regardless of whether it’s making chugging noises or not, as part of the routine maintenance practice. Follow the steps below to clean your lawn mower fuel filter.

Park your lawn mower and use the parking brakes to prevent it from moving.
Next, remove the fuel pump fuse.
Now release the pressure from the fuel system by letting the engine run for about two minutes.
Disconnect the battery terminals, preferably the negative terminal, to prevent the engine from starting on its own or to prevent gas fumes from igniting in the fuel system.
Next, you disconnect the fuel lines using a screw wrench.
You now eject the fuel filters.
Now, you can clean the clogged fuel filter. You start by draining all the fuel or dirt debris by tapping the filter on both ends.
Use a good cleaner, and then tap both ends once more. Then leave the filters under the sun to dry for about two hours.
Reinstall the fuel filter in the same seating when you removed it. Next, connect the fuel line and tighten the screw using the screw wrench.
Connect the battery terminals, and lastly, return the fuel pump fuse.

Clean the mower deck

You should check your lawn mower deck as the grass gets caked on the underside. You should wash it preferably after mowing your lawn. Follow the steps below to clean the deck of your lawn mower.

Empty the gas tank and then disconnect the spark plug wire.
Stand the mower up on its side.
Take the garden hose, and spray the deck till some dirt and caked-on grass loosen.
Scrub off the rest of the remaining debris using a brush, soap, and hot water.
Rinse, and then allow the metal deck to dry for about one hour.

Why is my lawn mower making a rattling noise?

The reason your lawn mower is making a rattling noise is because of loose bolts and nuts that needs to be tightened, or a loose blade assembly that can happen if it moves around during start-up. A worn lawn mower deck spindle can also cause your lawn mower make a rattling noise.

Loose bolts and nuts

The engine vibration loosens the nuts and bolts over time. Loose nuts and bolts cause some parts of your lawn mower, such as the engine cover, the wheels, the deck, and the handles, to become loose, causing your lawn mower to make a rattling noise.

Loose blade assembly

If the blade assembly of your lawn mower is loose, it will move around during start-up and can cause a rattling noise as your lawn mower runs. The blade itself can sometimes be bent, and can cause a lot of rattling noise.

Worn lawn mower deck spindle

A worn lawn mower deck spindle makes your lawn mower vibrate and can make a rattling noise—a lawn mower spindle assists in transmitting the engine’s power to the blade. A spindle has an inner part that connects to the pulley and the blade.

How to fix a lawn mower that is making a rattling noise?

To fix a lawn mower that makes rattling noises, you can tighten the loose nuts and bolts, repair the lawn mower deck spindle if its bearings are worn, tighten the blade assembly if it’s loose, or replace the blade if it’s bent.

Tighten the loose nuts and bolts

You should go over your lawn mower to check for the tightness of each nut and bolt. Tighten the loose nuts and bolts using the correct spanner size. Follow the steps below to tighten the loose nuts and bolts.

Locate the loose nut or bolt.
Fit the spanner onto the nut.
Hold the shaft of the spanner and turn it clockwise. Keep turning till the nut is too tight to be turned quickly.

Repair worn lawn mower deck spindle.

As soon as your lawn mower makes rattling noises, stop the engine and check the lawn mower deck spindle. You can repair the spindle by replacing the worn bearings if the spindle is worn. Follow the steps below to repair your lawn mower deck spindle.

Remove the deck from the lawn mower to make it easy to remove the spindle.
Remove the blade and the pulley from the worn spindle.
Next, remove the worn spindle from the deck.
Now, take apart the spindle assembly to replace the worn bearing.
Reinstall the pulley nut onto the spindle shaft.
Then, hit the nut with a single sharp hit from a small sled.
Now you will be able to remove the shaft from the spindle casing. You will be left with the spindle casing with the top and bottom bearing exposed.
Now use a screwdriver to remove each bearing from its seat.
Go to your local auto store and purchase a new, correct number of bearing as indicated on the side of the old bearing. A single bearing costs about $56.
Clean all the parts well.
Place one of the new bearings into the lower bearing seat. Then place the upper bearing.
Reinstall the shaft to the spindle.
Using a pipe, press the retaining sleeve onto the spindle.
Put the repaired spindle back onto the deck.
Reinstall the deck back onto your lawn mower.

Replace bent blades

You should always check the blades, and if broken, you should replace them. Follow the steps below to replace your lawn mower blade.

Disconnect the spark plug wire to prevent the engine from starting.
Then turn your lawn mower on its side.
Put on heavy gloves to avoid being cut by sharp blades.
Hold the lawn mower blade by lodging a wood block between the blade and the mower to hold the blade in place.
Next, use an appropriate wrench to loosen the fastener holding the blade to the drive shaft.
After removing your lawn mower blade assembly, go to your local auto stores and purchase a new blade, the same size, and shape as the old one. Then sharpen the blade using a metal file. Depending on the type and brand, a lawn mower blade costs between $12 and $31.
Assemble the blade assembly, following the owner’s manual procedure.
Take off your working gloves. Remove the wooden block, and tighten the bolt using an appropriate wrench.
Connect the spark plug wire and flip your lawn mower back upright.