The short answer
Look for hardware before parts. On an Alliance commercial dryer the leading noise source is pocket debris in the drum, the lint compartment or the blower — a machine loaded by many people collects it daily. Worn drum rollers come second as a duty-cycle wear item, the belt and idler third, and a loose blower wheel or an unsecured machine last.
What you observe
- A metallic rattle that rises and falls with speed — Something loose in the blower path.
- A steady rumble that grows over weeks — Drum support rollers wearing out.
- A squeal at start-up that fades when warm — The idler pulley or a glazed belt.
- The machine rocks or knocks its neighbour — Not levelled or not secured in the bank.
- NEAR MISS — a roar that is simply airflow — A commercial blower is loud by design.
Causes, most likely first on this class
- Coins, buttons or keys in the drum or blower path — First because the machine is loaded by people who did not check their pockets, every day, all day. It costs nothing to find and it explains most metallic noise on this class.
- Drum support rollers worn by duty — Second: rollers are consumables on a machine running most of the day, so a growing rumble is a maintenance interval arriving rather than a failure.
- Belt glazed, or idler pulley worn — Third, and heard as a squeal that fades as the machine warms. Again a duty item, and the usual companion to worn rollers.
- Blower wheel loose, or machine not secured — Last: a wheel slipping on its shaft or a dryer unlevelled in a bank hammers everything around it, and both need a service visit.
Check in this order, and why
- Isolate the machine and empty the drum and lint compartment — Free, fast, and the top cause on this class.
- Note whether the noise is metallic or a rumble — Metallic means hardware; a rumble means rollers.
- Listen at start-up for a squeal that fades — That separates the belt from the rollers.
- Check the machine is level and secured in its bank — Left until here because it needs the noise identified.
What an owner can safely check
- Isolate power and gas, then sweep the empty drum by hand — Feel around the drum lip and the baffles.
Tools: gloves, torchAbout 20 min
- Pull and clear the lint screen and its compartment — Coins collect below the screen more often than in it.
Tools: gloves, vacuumAbout 25 min
- Run the machine empty and classify the noise — Metallic, rumble or squeal, and whether it changes when warm.
About 30 min
- Check the machine sits level and is secured in the bank — It must not rock, walk or touch its neighbours.
Tools: spirit levelAbout 25 min
- STOP HERE if the noise means opening the cabinet — Rollers, belts and blowers are behind a gas train.
Before you open anything
Safety
If you smell gas, do not operate any switch and do not touch the machine: leave the building and call the gas emergency number from outside. Otherwise isolate the machine at its disconnect and close its gas cock before opening any panel; a capacitor can hold a charge after the power is off. Never bypass a door or lid interlock to run a machine with a panel open. Gas connections and the gas train are for a qualified engineer only.
When to call a technician
Call when the drum and lint compartment are clear and a rumble, squeal or knock remains — rollers, belt, idler or blower are then the answer and all of them sit behind panels carrying a gas train. Book it as maintenance rather than waiting for a breakdown, because these are duty items. Stop the machine and call the gas emergency number from outside if you smell gas.
Nearest pages of this class
What this page does not cover
This page is written for the brand and the appliance class, not for one family or model line. Where a family- or model-specific page exists for your unit, that page is the more specific answer and you should start there. Deliberately absent: roller, belt and blower part identifiers, drum capacities, duct sizes and fault-code meanings, all of which differ between the single-pocket, stacked and tumbler families.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
