Stop and unplug it. A hot or burning smell is one of the few sewing machine symptoms that warrants stopping immediately rather than investigating while running.
Work out which smell it is, once it is off and cool.
Hot rubber — a slipping drive belt, or the bobbin winder tyre left in contact with the handwheel. Look for a glazed shiny patch on the belt and check the winder spindle is disengaged.
Hot oil — usually harmless on a recently oiled machine, and it fades after a few minutes of running. Over-oiling produces it, and so does oil applied where the manual does not call for it.
Overheated motor — a warm, dry smell after a long session under load. Domestic motors are not rated for continuous heavy work; let it cool for half an hour. Recurring overheating on ordinary work is a fault.
Electrical, sharp and acrid — this one is different. A burning plastic or fishy chemical smell suggests wiring, the pedal or a board, and the machine should not be plugged in again until someone has looked at it. Check the pedal and the mains lead for discolouration or damage.
Then check for mechanical drag. Unplugged, turn the handwheel by hand. If it is stiff, the mechanism is being forced and the motor is heating as a result — clean and oil the hook area before anything else.
A machine that smells hot and has become noisy is asking for a service, not another seam.
Questions people actually ask
It only smells hot on heavy fabric.
The motor is labouring. Reduce speed, lengthen the stitch, fit a heavier needle, and accept that the fabric may be beyond the machine.
Is a faint oil smell after servicing normal?
Yes, for the first hour or so of running. Sew on a scrap first so any excess oil marks that rather than a garment.
Last reviewed 2026-08-11