The short answer
A new noise from a Bosch WTG dryer is a location problem before it is a parts problem, and the drum is where most of them are. On the seven models below the noise that arrives gradually is almost always a rotating support wearing, while the noise that arrives suddenly is almost always something that should not be in the machine at all. Those two stories separate in the first minute, without tools.
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 WTG family.
Causes, most likely first on the WTG family
- Bearings and rotating supports under load — First on the WTG family where the noise is load-dependent. A support that is fine empty and loud full is carrying weight it can no longer carry cleanly, and it will not recover.
- Belt and idler — Second. These give the characteristic squeal, they are worst from cold, and they can change week to week with humidity, which is why owners describe them as intermittent.
- Foreign objects and the drum seal — Third here rather than first, because a noise that changes with load is unlikely to be a loose coin. Still worth a look, since it is free.
- Cabinet, ducting and installation — Last. The noise is real but the fault is not inside the machine, and on the seven models below it is fixed by moving or levelling rather than by repairing anything.
Check in this order, and why
- First: establish whether the noise tracks rotation — Once per revolution is something attached to or in the drum; continuous is a support or the drive.
- Second: test cold and warm — Run the machine at the start of the day and again after a cycle. A noise that fades as things warm points at a belt or an idler rather than a bearing.
- Third: isolate and rotate by hand — Breaker off, drum turned slowly through several full revolutions. You are feeling for one rough spot per revolution as against a general roughness.
- Fourth: stop at the panel — Supports, belts and idlers on the WTG family sit behind fixed panels, and the drum has to be supported while they are reached. That is where this becomes a service call.
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 WTG family
Reference| Model number | Family key |
|---|---|
| WTG86400UC | bosch:dryer:wtg |
| WTG86401UC | bosch:dryer:wtg |
| WTG86402UC | bosch:dryer:wtg |
| WTG86403UC | bosch:dryer:wtg |
| WTG865H2UC | bosch:dryer:wtg |
| WTG865H3UC | bosch:dryer:wtg |
| WTG865H4UC | bosch:dryer:wtg |
When to call a technician
The line on the seven 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 WTG 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 WTG family
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
