The short answer
Rumble, squeal, thump and rattle are four different faults on a dryer, not four descriptions of one. On the three models below the first is usually a support, the second a belt or a bearing under load, the third something loose in the drum or the load itself, and the fourth something that has fallen where it does not belong. Name the noise first and the diagnosis gets short.
What you observe on these models
- A low rumble that rises with the drum — Regular, tracks rotation, and gets worse over weeks rather than arriving in one day.
- A squeal or chirp that comes and goes with load — Loudest when the drum is heavy, quieter when it is nearly empty.
- A rhythmic thump once per revolution — Something attached to the drum, or a load that has bunched into one mass.
- A metallic rattle that is not in time with anything — A coin, a button or a clip in the drum seal or the air path.
- NEAR MISS - a hum with no drum movement — That is a drive or start fault and belongs on the no-start page for the WQB family.
Causes, most likely first on the WQB family
- Drum supports: rollers, glides or bearings — First on the WQB family. They carry the whole weight of a loaded drum through every rotation, they wear gradually, and they give exactly the rising rumble owners report. The wear is slow enough that owners adapt to it and only call when it has become obvious.
- Foreign objects in the drum seal or the air path — Second, and the most satisfying to find because it costs nothing. Coins and clips work past the drum edge and then rattle at a frequency that has nothing to do with rotation.
- Belt, idler or drive components — Third. A belt that has hardened or an idler that is stiffening produces a squeal that changes with load, and it tends to be worse when the machine is cold.
- Installation: levelling, feet and cabinet contact — Last as a cause of true noise, but first as a cause of what owners describe as vibration. It is worth ruling out early because it needs no parts at all.
Check in this order, and why
- First: name the noise — Rumble, squeal, thump or rattle. Everything below branches on this, and a recording made on a phone at the machine is worth more to a technician than any description.
- Second: turn the drum by hand with the machine isolated — Switch it off at the breaker first. Roughness, notchiness or a grinding feel confirms a support before any panel comes off.
- Third: run it empty, then run it loaded — Noise that scales with load is a support or a bearing. Noise that does not is usually loose material or installation.
Before you open anything
Safety
Switch the dryer off at the breaker before reaching into the drum to feel the seal, and before turning the drum by hand; a capacitor can hold a charge after the power is off. Do not run the machine with a panel removed to locate a noise. A drum that is supported on worn parts can move unexpectedly once a panel is off, which is why this particular job is not an owner job past the inspection stage.
Models in the WQB family
Reference| Model number | Family key |
|---|---|
| WQB235B8AU | bosch:dryer:wqb |
| WQB245AXUC | bosch:dryer:wqb |
| WQB245B0UC | bosch:dryer:wqb |
When to call a technician
The line on the three models below is whether the noise survives an empty drum and a properly levelled machine. If it does, and particularly if it has grown over weeks, the machine needs opening. Stop using it if the noise is a grind: a support that has worn through damages the drum it carries, and that turns a modest repair into a larger one.
Sources — The symptom-report corpus recorded against Bosch WQB dryer pages for this fault is cited below. No share is quoted from it anywhere on this page: the snapshot reaches this page as a provenance chain without values, so every ordering here is technician judgement rather than a measured proportion.
Documented- amazon-reviews — amazon-reviews, fetched 2026-09-02
Other faults covered for the WQB family
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
