Why is My Weed Eater Making a Noise (Grinding, Popping & Rattling)?

Why is my weed eater making a grinding noise?

The reason why your weed eater is making a grinding noise is because of a faulty clutch due to wear and tear due to repeated use or a faulty drive shaft which may have a micro-fracture or become bent. A clogged-up gearbox that has become contaminated with dirt or weeds could be another reason your weed eater is making a grinding noise.

Clutch problems

The clutch assembly consists of a metal housing and a pair of spring-loaded boots. When the engine is idling, the springs keep the boots together to prevent the head from spinning. However, once you engage the throttle, the boots are separated, and they contact the housing and cause it to spin. The house then drives the rotation of the drive shaft and, by extension, the trimmer head.

Like all mechanical parts, wear and tear of repeated use could cause damage to parts of the clutch assembly. In addition, damaged springs or fractures to any metal parts will produce a grinding noise when you engage the throttle. The erratic spinning of the head could also accompany this noise.

Drive shaft problems

The drive shaft transfers the rotation generated from the engine to the spinning head. It rotates inside the long hollow handle of your weed trimmer. Like all metallic parts of an engine, the drive shaft of your trimmer needs lubrication to run smoothly.

It generates vibrations if it is running poorly inside the tube. Also, if running dry for a long time, it could have some micro-fracture or become bent. In this case, you need to replace the shaft.

Clogged up gearbox

The gearbox is at the junction of your drive shaft and mowing head. It is responsible for the unspooling and spinning of the rope at the head of your weed eater.

If weed or dirt gets trapped in the gearbox, it will force the drive shaft and engine to work harder to produce the spinning. This could then cause the trimmer to make a grinding noise while using it.

How to fix a weed eater that is making a grinding noise?

You can clean out the gearbox, lubricate the drive shaft and replace the worn-out part in the clutch assembly to fix a weed eater that is making a grinding noise.

Clean out and grease the gearbox

A dirty and clogged-up gearbox could be why your weed eater is making a grinding noise. Follow these steps to remove and clean it:

Shut down the weed eater and lay it down on a flat surface; a table would be ideal.
If you recently used the trimmer, use a rag to clean off the dust from the head. Near the head, there should be two screws. One is for greasing the gearbox, while the other is for removing it.
Start by loosing the screw closest to the ropes.
Insert the tip of a weed eater gear grease into the hole.
Squeeze the tube of the grease while rotating the head.
If this doesn’t get rid of the grinding noise, go ahead to loose the second screw. The head of the weed trimmer should come right off.
In the center of the head, between the robe, there is a screw. Loose this screw to expose the wires loop and the three screws that secure the gearbox.
Loose these screws and clean the gearbox with compressed air or a lint-free rag.
Recouple the head using and secure the screws back in place.
Ensure you regrease the gearbox using the information above after cleaning it.

Lubricate the drive shaft

A drive shaft running dry could cause your weed eater to make a grinding noise. Follow these instructions to lubricate your drive shaft:

Switch off your weed eater and allow it to cool down.
Remove the head of the screw using the bolt closer to the shaft.
Remove the tiny bolt on the side of the lower end of the shaft. This is the greasing hole.
Insert the tip of a weed eater gear grease into the hole.
Squeeze the tube of the grease while rotating the shaft. This non-invasive method should get you going for a day to day use.
Twice a year (depending on the usage of your weed eater), gently pull out the drive shaft in the handle. It could be a flexible or rigid cable. The end of it will stick out from where you remove the head.
Remove the old grease present inside the metal casing.
Reapply new grease on the shaft and reinsert it. Ensure it sits right into the end of the clutch.
Reattach the head of the trimmer and secure it with the screws.

Repair the clutch assembly

Damaged springs or fractures to any of the metal parts of the clutch assembly could cause a grinding noise in your weed eater. Follow these steps to diagnose and fix this correctly.

Remove the bolts that hold the shaft to the engine.
Pull off the shaft and set it aside.
Unscrew the clutch cover.
If the springs are worn out, replace them with the appropriate springs for your weed trimmer model. They cost around $10 on Amazon.
If there is complete damage to the metallic surface or you notice any fracture. You need to replace the whole clutch assembly. They cost around $22 on Amazon.
Install the new clutch.
Fasten the shaft back onto the engine using the screws you removed earlier.

Why is my weed eater making a popping noise?

The reason why your weed eater is making a popping noise is because of a failing spark plug because of long time usage or a clogged exhaust screen. A clogged carburetor that has the wrong tuning or a loose connection could be another reason your weed eater is making a popping noise.

A failing spark plug

A spark plug is responsible for delivering electric current to the compressed fuel/air mixture to start the combustion process. Over time, this device could get spoilt. A bad spark plug could produce a lot of symptoms. Ranging from trouble starting, engine misfiring, and popping noise when you start the engine.

Clogged exhaust screen

The exhaust system of your weed eater consists of a muffler to reduce the noise and a spark arrester. The spark arrester is a mesh-like device (screen) that prevents debris from your engine from being released into the environment.

Continuous use of your machine causes the mesh to get clogged up. When this occurs, the particles ignite in the exhaust system and release black smoke while making a popping noise.

Carburetor problems

A clogged-out carburetor, wrong tunning, or a loose connection between the carburetor and the air filter can cause your weed eater to make popping sounds.

How to fix a weed eater that is making a popping noise?

You can change the spark plug, clean the exhaust screen, tighten the air filter or clean out the carburetor to fix a weed eater that is making a popping noise.

Change the spark plug.

A bad spark plug could cause a popping noise in your weed eater. Follow these steps to change the plug.

Ensure your engine has cooled off after shutting it down.
Remove the black wire at the end of the spark plug (spark plug boot).
Use a ¾-inch socket or a plug wrench to loosen the plug for removal.
Buy a replacement spark plug that meets your weed eater manufacturer’s specifications. They are available on Amazon for around $10 for a pair.
Thread the new spark plug into the cylinder. Tighten it with a socket.
Attach the wire back onto the spark plug.

Clean the exhaust screen

A dirty and clogged-up exhaust system could cause a popping sound in your weed eater. Follow these instructions to clean it:

Remove the covering of the air filter and set it aside.
Next, loose the two bolts that hold the engine cover in place. They should be present on the extreme ends of the cover.
Slightly tilt your weed eater, so the carburetor side is facing down.
Remove the three screws that hold the metal plate covering the spark arrester. You will need a T25 screwdriver to loosen them. The plate should be prominent as it is usually covered in dark soot.
Gently remove the mesh-like substance underneath the plate. This is the screen of the spark arrester that you need to clean.
Brush off the debris on it using an old toothbrush. Do that until the mesh is clean and you can see through its holes.
Once the screen is clean, replace the mesh, then the cover plate. Finally, hold the cover plate in place using those screws you removed.
Replace the engine cover and the air filter cover.

Fix carburetor problems

Carburetor-related problems could also cause the popping noise in your weed eater. Follow these step-by-step guides to fix it:

Locate the adjustment screws on the top of your carburetor. They should be labeled “Hi” and “Lo .”
Use a small Philip screwdriver to tighten these screws. Some models require using a carburetor adjustment screwdriver. You can improvise this by using the tip of the case of a Bic pen.
Turn the screws about one turn counterclockwise.
Turn on the engine, and slightly turn the “Lo” screw clockwise until the engine sounds evens out.
Then rev up the throttle. If the engine sputters or dies, turn the “Hi” screw counterclockwise until it evens out.
Do this until the engine’s sound evens out and you can no longer hear a popping sound.
If your air filter is starving your engine of cool air, it may cause the engine to overheat. First, remove the air filter cover by turning the knob on the end of the cover.
Assess the air filter for any tear or clogging.
Remove the old filter and install the new one. Air filters are available on Amazon for around $10 for a pack of 5.
Strap the air filter cover back onto your trimmer and secure it tightly.

Why is my weed eater making a rattling noise?

Your weed eater is making a rattling noise because the set screws that have become loose due to vibrations from the engine or worn-out clutch assembly.

Loose set screws

Your weed whacker is made up of several smaller moving parts. The shaft connects the engine through four screws. Screws also connect the shaft to the head of the whacker.

Vibrations from the engine can shake loose those snug bolts. The vibrations of such screws give off a rattling sound as you use your trimmer.

For this reason, Stihl recommends checking for loose screws and other parts after every use, so you can spot them early and tighten them. Check all of the screws connecting the shaft to the power head, the throttle control lever to the shaft, and the shaft to the gearbox.

How to fix a weed eater that is making a rattling noise?

You can check and tighten loose set screws or replace worn-out parts in the clutch assembly to fix a weed eater that is making a rattling noise.

Tighten loose screws

Loose set screws could cause the rattling noise in your weed eater. Follow these step-by-step guides to fix it:

First, ensure the engine has cooled off after switching it off.
Then, lay the weed eater on a flat surface.
Look for any junction where screws are used to secure the parts. Try to move it with your hand.
If it is movable, tighten it with your screwdriver.
Repeat this at least once weekly to keep your whacker nice and snug.

Fix clutch problems

Damaged springs or fractures to any of the metal parts of the clutch assembly could cause a rattling noise in your weed eater. Follow these steps to troubleshoot and fix this correctly.

Remove the bolts that hold the shaft to the engine.
Pull off the shaft and set it aside.
Unscrew the clutch cover.
If the springs are worn out, replace them with the appropriate springs for your weed trimmer model. They cost around $10 on Amazon.
If there is complete damage to the metallic surface or you notice any fracture. You need to replace the whole clutch assembly. They cost around $22 on Amazon.
Install the new clutch.
Fasten the shaft back onto the engine using the screws you removed earlier.