First, take everything out of the drum, including the lint screen, and listen to one minute of the empty drum spinning. If the thumping is rhythmic and tied to drum rotation, the issue is internal (rollers, belt, idler pulley, or blower wheel). If the thumping is irregular and happens during loads but not empty, the most common cause is uneven loads or a foreign object that's still loose in the drum. The internal causes are mostly appliance technician work, but the load and foreign-object check is something to do first because it's free.
Quick checks
- Is the dryer level on the floor?
- Empty the drum and listen. Does the thumping continue?
- Check pockets of recent loads for coins, keys, lighters, screws, or coin batteries.
- How long since the last load (a dryer unused for weeks can flat-spot the rollers and thump briefly)?
- Any squeaking or scraping mixed in with the thumping?
- Recent move or vibration from another appliance nearby?
If the empty drum still thumps
The thumping is mechanical. The most likely sources:
- Worn drum support rollers. Two or four small rollers under the drum let it spin freely. They wear flat or develop cracks over years. Symptoms: rhythmic thumping that matches drum rotation, gets worse over months. Replacement is appliance-tech work that involves opening the cabinet and lifting the drum.
- Failing idler pulley. The idler pulley keeps tension on the drive belt. It usually announces itself with squeaking first, then thumping or scraping. Replacement is also appliance-tech work.
- Drive belt damage. The drum belt can develop hard or split sections, especially with age. A piece of belt slapping the drum makes a regular thump. Belt replacement requires opening the cabinet.
- Blower wheel issue. The blower wheel sits in a housing behind the drum and moves air through the dryer. If lint or a small object lodges in the blower, or the wheel works loose on its shaft, you can get a thumping that changes with airflow.
- Loose drum baffles. The plastic or metal fins inside the drum can crack or come loose. Easier to spot visually with the drum empty.
You can sometimes localize the noise by turning the empty drum slowly by hand with the dryer unplugged. A rough or thudding rotation often points to rollers or a foreign object trapped between drum and outer cabinet.
If the empty drum is quiet
The thumping is load-related, not mechanical. Common causes:
- Unbalanced load. A single heavy item (rug, blanket, jeans) clumped to one side of the drum makes a regular thump every rotation.
- Wet load. Clothes that came out of the washer with too much water (washer spin problem) drip and clump, which sounds like thumping.
- Items in pockets. Loose change, keys, a stray screw, a small electronic. Walk the floor near the dryer first; a coin can fall out and roll around the drum for an hour before exiting through the lint slot.
- Foreign object in the drum but not visible. Things that slip between the drum and the front bulkhead can rattle. Check the lint screen slot for anything trapped.
If the dryer was unused for weeks
When a dryer sits, the drum's weight rests on a small area of the support rollers. The rollers can flat-spot in that area, which causes thumping when the dryer starts up. After 5 to 10 minutes of running, the flat spots usually round back out and the thumping stops. If it doesn't fade after 10 minutes, the rollers are likely worn and replacement is needed.
If you hear a metallic clink with the thumping
Something metal is loose. Common: a screw from the dryer cabinet that backed out, a piece of a broken baffle, a forgotten item from a previous load. Stop the dryer, unplug it, open the drum, and look. If nothing visible, that's an appliance-tech call to open the cabinet.
What not to do
- Don't keep running a dryer with a sharp metallic noise. Loose metal in the blower can puncture the venting or damage the heating element.
- Don't open the cabinet on a gas dryer unless you know how to disconnect and reconnect a gas line safely. Service it.
- Don't ignore a rising vibration. Excessive vibration can loosen ducting, gas connections, or electrical terminals.
When to call for service
- Empty-drum thumping that doesn't fade after 10 minutes of running.
- Squeaking, scraping, or grinding mixed with the thumping.
- Burning smell along with the noise.
- Any visible cabinet damage, scorching, or wiring issues.
- Gas dryer with mechanical noise (don't open the cabinet yourself).
- Repeated load-related thumping with no obvious cause after pocket and load checks.
Good maintenance rhythm
- Every load: clean the lint screen. Don't dry plastic, foam, or anything sealed against the drum surface (it can flat-spot the rollers).
- Every load: check pockets before starting. Coins and screws are the most common cause of mystery clinks.
- Every 6 to 12 months: pull the dryer out, level it, and vacuum behind it.
- Yearly: clean the full dryer vent path. A vent that runs poorly makes the dryer run longer, which wears the belt, rollers, and pulley faster.
- After hearing squeaking: schedule a service visit before it becomes thumping. Catching the idler pulley before it fails fully is cheaper.
- Track the dryer's age. Drum rollers and belts commonly need replacement at 8 to 12 years on a dryer that gets daily use.