A rhythmic thump-thump-thump from the dryer, or a loud bang that makes you jump, is hard to ignore. We hear about it a lot from Calgary homeowners. Sometimes the cause is as simple as a pair of running shoes. Other times it is a worn part inside the cabinet that will get louder with every load and eventually stop the drum altogether.
The trick is to listen carefully. When the noise happens, how often it repeats, and whether it changes with an empty drum all point to different parts. Here is how to tell the difference, what you can safely check, and when a thumping dryer needs a technician.
Start with what is in the drum
The most common thumping noise has nothing to do with the dryer. Shoes, heavy jackets, a single wet towel balled up, or sheets that have wrapped themselves around the rest of the load will thud against the drum as it tumbles. Try running the dryer empty for a minute. If it is quiet, the load was the problem.
For sneakers and boots, use the drying rack if your dryer came with one, or let them air-dry. For bulky items like duvets and winter coats, add a couple of dry towels to spread the weight, and stop the cycle halfway to untangle sheets. Zippers, buckles and toggles on jackets also knock against the drum; zip them up and turn the garment inside out.
Match the sound to the cause
Once the drum is empty, the pattern of the noise tells you a lot. This table covers the sounds we hear most on service calls.
| What you hear | Likely cause | Who fixes it |
|---|---|---|
| Thud only with certain loads | Shoes, tangled or heavy items | DIY: change the load |
| Steady thump, even when empty | Flat-spotted drum roller | Technician |
| Slap once per belt turn | Damaged belt or worn idler | Technician |
| Rocking knock, dryer moves | Dryer not level | DIY: adjust the feet |
| Rattle or bang from the base | Object in the blower | Technician |
| Single bang as the burner lights | Delayed gas ignition | Technician, stop using it |
Worn parts inside the dryer
Flat-spotted drum rollers
If the dryer thumps even when empty, the most likely cause is a drum roller with a flat spot. Rollers are rubber wheels that support the back, and on many models the front, of the drum. When a dryer sits unused for a while, or a roller's rubber hardens with age, a flat side can form. Every time the roller turns over that spot, you hear a thump. The noise is steady and keeps time with the drum, and it often fades a little once the dryer warms up.
Worn rollers often squeak before they start thumping. If you are hearing both, read dryer squeaking and squealing noises too. Rollers are normally replaced as a set, along with their axles if those are worn.
The drive belt
A belt with a lump, a frayed section or a damaged seam can make a thumping or slapping sound once per belt turn. Belts also wear and stretch, and a belt that is close to snapping often gets noisy first. If it does break, the motor runs but the drum will not turn. See dryer drum not turning: broken belt, and our dryer not spinning repair page for what we check when the drum has stopped.
Idler pulley and drum glides
The idler pulley keeps tension on the belt. When its bearing wears, the pulley wobbles and lets the belt slap against the cabinet. Drum glides, the felt or plastic pads the front of the drum rides on, can wear through and let the drum drop and knock as it turns.
Levelling and how the dryer sits
A dryer that is not level rocks as the drum turns, and that can sound like thumping or knocking. The drum and its rollers also wear unevenly when the cabinet sits at an angle, so a levelling problem can turn into a roller problem over time.
Basement and closet floors
Basement slabs often slope toward a floor drain, and laundry closets sometimes have a lip or a seam in the flooring right under one foot. Check that all four feet touch the floor and the dryer does not move when you press on opposite corners. Most dryers have screw-in front feet you can turn by hand or with a wrench, and some have self-adjusting rear feet that settle when you tip the dryer forward slightly and set it down. Rubber anti-vibration pads under the feet can also help on hard tile.
Stacked units
Stacked units need to be secured with the manufacturer's stacking kit. Without it, the dryer can creep across the top of the washer during spin and knock with every turn of the drum. If yours is shifting, stop using the pair and have it looked at. Our stacked dryer repair page explains what we check.
Other causes of banging
- Loose items in the blower. Coins, buttons or a sock that got past the lint screen can bang around inside the blower housing.
- A loose or cracked baffle. The fins inside the drum can come loose and knock with each turn.
- The vent duct knocking against a wall or joist as air pulses through. Noisy, but usually harmless.
- A worn motor bearing or motor mount, which gives a deeper rumble or knock that follows the motor rather than the drum and often grows louder over a few weeks.
- A loose rear panel or cabinet screw, which buzzes and rattles more than it thumps.
On gas dryers, a single loud bang or whoomp when the burner lights is a different matter. Delayed ignition is not something to live with, so stop using the dryer and call. Our gas dryer repair technicians deal with burner and ignition problems.
Safe checks before you call
Unplug the dryer before you touch anything inside or behind it.
- Run the dryer empty for a minute to rule out the load, then unplug it again.
- Check the drum for coins, keys and buttons, and shine a flashlight into the lint screen slot.
- Make sure the baffles inside the drum are tight and not cracked.
- Put a level on top of the dryer, front to back and side to side, and adjust the feet.
- Turn the drum slowly by hand. Feel for a bump or catch once per turn, and note whether the drum feels loose or drops at the front.
Do not remove panels while the dryer is plugged in, and on gas dryers leave the gas line and valve alone. If you ever smell gas, leave the house and call ATCO Gas emergency at 1-800-511-3447.
When to call a technician
If the thumping continues with an empty, level dryer, a roller, belt, idler or glide is likely worn. Catching it early usually means a simpler repair, because a failing roller can damage the drum or snap the belt if it is left too long. If your dryer is older and the noise is one of several problems, our guide on whether to repair or replace a dryer can help you decide. Fast Appliance Repair fixes noisy dryers of all brands, from Calgary SW to Strathmore and Airdrie. Ring (587) 779-6919 for same-day service. You pay a flat diagnostic fee, get a full quote before any work, and every repair comes with a 90-day parts and labour warranty.