Ask MAKE: Cleaning an old motor?

Ask MAKE is a weekly column where we answer reader questions, like yours. Write them in to mattm@makezine.comor drop us a line on Twitter. We can’t wait to tackle your conundrums!


Andy writes:

Recently I acquired a vintage Leslie speaker cabinet. The speaker cabinet uses ac motors to turn baffles and horns to create a Doppler effect. Upon opening up the speaker, I found that the motors were working, but very dirty and coated with gunk. What is the best way to clean a motor with an excess of build up?

Congratulations on your acquisition! Since the motors seem to be working fine, my guess is that it might be best to clean them cosmetically, but not to try and take them apart and rebuild them. Even though they are electrical devices, you should be able to clean them like anything else, using some form of solvent and a brush. Just make sure to let them dry out completely before you power them up!

I would start a mild detergent (soap and water). If that doesn’t do the job (which it probably won’t), try mineral spirits or a specialized electric motor cleaner. The biggest things I can think to look out for when using a solvent to clean the motor are that it doesn’t damage the varnish on the motor windings or get into any greased bearings. The varnish is used as a coating on the motor windings, to keep them from touching each other and shorting out, so removing it would not be a great thing to do. If the motor does have greased bearings, you might want to lubricate them as well.

I’ve taken apart a few motors, but admittedly don’t have a lot of experience in this field. Does anyone have a favorite technique or solvent that they use to restore vintage machines like this?