KitchenAid mixer grinding noise: what it means and what to do

What the worm gear does

Inside the head, a worm gear passes the motor’s spin down to the gears that turn the beater. It is made of plastic, on purpose: it is meant to wear out or strip before the motor and the harder parts take the damage.

When its teeth strip, the motor keeps running but the beater turns slowly, stutters or stops. That is the classic sign.

Signs of a worn worm gear

• A grinding or whining noise that is new, or getting louder
• The motor runs but the beater stops or stutters, especially with dough
• Bits of plastic or metal shavings in the old grease
• An oil leak or dark grease showing at the same time

Other causes of a noisy mixer

Old grease that has dried out or broken down stops protecting the gears, and heavy dough loads and heat wear them faster. On an older machine other gears can wear as well. Some noise is normal, because these mixers are not quiet, so the key question is whether the sound has changed.

What to do

Our worm gear replacement and re-grease fits a new worm gear and gasket, cleans out the old grease and repacks the mixer with fresh food-grade grease, then test runs it under load. If you are not sure what is wrong, the diagnostic finds the actual fault, and its price comes off the repair if you go ahead.

1. Stop using the mixer and unplug it. Running it on can cause more damage.
2. Do not mix anything heavy while you decide.
3. Have it looked at. It is a repair many handy people do at home, but it means opening the gearcase, cleaning out the old grease and refilling it correctly.

Older mixers can grind too

Older machines such as the K45SS and K5SS can develop the same problem, and they are usually worth repairing. If you are not sure how old yours is, our serial number decoder will tell you when it was built.