Direct answer
For the LG WT8405CW top-load washer, residue, trapped moisture and a restricted drain path should be corrected before deodorizing. First, inspect the gasket, dispenser, filter and tub after removing laundry.
What this covers
- LG WT8405CW top-load washer (WT8405CW)
- LG top-load washer; ThinQ-enabled controls and menu paths vary by model.
- The specific fault this record addresses: smells musty, sour or like mildew
What it does not cover
- ×The same symptom on a different LG product line, which has its own record and its own cited source
- ×An on-screen error code whose meaning has not been checked against this exact model's manual
- ×Live electrical, gas, sealed-system, internal battery-cell or structural repair — a technician boundary, not a self-service step
Differential
What actually causes this, and how to tell them apart
These are ordered by how often each one is the answer, not by how easy it is to try. The point of the middle column is that two causes producing the same headline symptom rarely produce the same detail — that detail is what tells you which one you have before you change anything.
- 1
Residue in the dispenser drawer and its housing
What separates it Smell concentrated at the drawer, with visible slime or crust in the drawer recess.
How to confirm Remove the drawer entirely and clean both it and the cavity it sits in — the cavity is frequently missed.
- 2
Habitual over-dosing of detergent or fabric softener
What separates it Recurring odor with heavy residue everywhere, and suds problems on ordinary loads.
How to confirm Excess product does not rinse away; it becomes the food source for the biofilm — see suds-foam.
- 3
Wet laundry is being left in the drum after cycles
What separates it The smell transfers to the clothes as well as the machine, and is worst after a load has sat.
How to confirm Removing loads promptly resolves the clothing smell independently of cleaning the machine.
Before you touch a setting
Record this first — changing settings destroys the evidence
Every item below stops existing the moment a reset, re-pair or settings change is made. Written down first, they are what separates the causes above; recovered afterwards, they are guesswork.
- Where the smell is strongest — the door seal, the dispenser drawer, the drain filter area, or the clothes themselves.
- Whether the door and dispenser drawer are left open or closed between loads.
- When the drain pump filter was last cleaned.
- Whether the smell is musty and organic, or sharp and electrical — the latter is a different and more urgent problem entirely.
Remove the dispenser drawer and clean both the drawer and its cavity
ReversibleThe cavity the drawer sits in is routinely missed and holds residue.
Run the manufacturer's tub-clean cycle with the specified product
ReversibleDo this after the manual cleaning, not instead of it — a tub-clean cycle cannot reach inside the boot fold.
Model-specific
What is true of this model and not of its siblings
Generic advice for the product line fails here. Each item below is a property of this specific model family that changes which of the steps above apply to you.
- Model scope
- WT8405CW. LG top-load washer; ThinQ-enabled controls and menu paths vary by model.
- Type & capacity — TOP-LOAD
- 5.3 cu. ft. TOP-LOAD washer. The first thing to identify is whether your unit has a tall center AGITATOR post or a low-profile IMPELLER wash plate, because it changes correct loading and the 'clothes tangled / not cleaning' diagnosis: an impeller needs clothes loosely around the plate, not wrapped around a post.
- Motor — Direct Drive inverter (no belt)
- Belt-less Direct Drive inverter motor; noise/vibration is bearings and balance, not a belt.
- Top-load behaviour
- HE top-loaders use a low water level and sense the load, so 'the drum isn't full of water' is normal, not a fill fault. TurboWash 3D and ThinQ Wi-Fi feature on this tier. Lid-lock must engage before a spin; a spin that won't start is often the lid switch.
- Symptom boundary
- This record covers LG WT8405CW top-load washer when it smells musty, sour or like mildew. A different symptom on the same hardware, or this symptom on a different LG product line, has its own record with its own causes and its own cited source.
Stop boundary
When this stops being a self-service repair
Continuing past any one of these costs more than the repair saves — in safety, in warranty, or in evidence a technician needs.
- !A sewage smell rather than a musty one points at the household drain rather than the washer — check the standpipe trap rather than cleaning the machine further.
- !A sharp, acrid or burning-electrical odor is a different problem entirely: disconnect power and do not run the machine.
- !Never mix cleaning chemicals, particularly bleach with any acid or ammonia-based product, while cleaning a dispenser or seal that still holds residue.
Evidence ledger
Sources behind this answer
Visible sources support the visible claims. Home Product Support records the publisher, the fact used and the review date; community reports can suggest an issue but do not become a published fact on their own.
Where the manufacturer's article stops. LG publishes this as "[LG Washing Machine] Troubleshooting Musty Odors". Musty/sour/mildew smell and LG's gasket and tub-clean remedy. What that article does not carry is the model boundary — it is written for a product line, and WT8405CW is the scope applied here. Where a control label, terminal, indicator pattern or reset sequence differs on your unit, the manual for that exact model is the authority, not this page and not the article.
Exact questions
Common follow-ups
My LG WT8405 doesn't fill with much water.+
That is normal for a high-efficiency top-loader. It uses far less water than old machines and senses the load to add only what is needed, so you will not see the drum fill up — the clothes are cleaned by movement against the impeller or agitator, not by soaking. If it truly is not filling at all (a code, or bone-dry clothes), check the water supply valves and inlet screens.
My front-load washer smells musty no matter how often I run a clean cycle.+
A tub-clean cycle cannot reach inside the door boot seal's fold, which is where the biofilm actually lives. Pull the rubber boot's lower fold back by hand and clean the full circumference — you will usually find standing water and dark deposits there — then clean the drain pump filter housing and the dispenser drawer cavity.
Why do front-load washers smell more than top-loaders?+
They have more places that stay wet between loads: the door boot seal's fold, the drain pump filter housing and the dispenser drawer all retain water after every cycle. A top-load washer has no boot seal at all and drains more completely, so it gives biofilm far less to work with.
Does leaving the door open actually help?+
Yes, and it is the most effective preventative step available. Leaving the door and the dispenser drawer ajar between loads lets the seal, drum and drawer dry out, which removes the moisture the biofilm needs.
Does this answer apply to every LG model?+
No. It is scoped to WT8405CW. LG top-load washer; ThinQ-enabled controls and menu paths vary by model.
What should I record before troubleshooting odor or mildew or smell?+
Record the complete model identifier, exact message or indicator, software/firmware where visible, the operating stage and what still works.
Why is a factory reset not the first step?+
A reset can erase accounts, networks, maps, schedules or preferences without distinguishing odor, mildew, smell. The ordered checks preserve that evidence.
When should I stop and use qualified service?+
Stop for sewage backup, smoke, overheating or chemical mixing.
Answer for the exact device and software version shown above.