I have an old medium sized 1/2 HP electric [motor]. On the bottom, on both ends, there is a small (couple millimeter) hole blocked with red plastic plugs. They are on the same side as the mounting rig, on what I would call the bottom of the [motor] (the info plate is right side up when the plugs face the floor).

Looking online I see some engines have drainage holes that come stoppered with plastic plugs (you remove all of the ones that end up facing the floor). But I have been told that these [motors] sometimes come with similar stoppered holes for oiling. How would one go about telling the difference?

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  • You see, in your description, you talk about "engine". In most cases when I see the word "engine" I automatically think of an internal combustion engine. Electric "engines" are most often called "motors". I'm very happy you've provided pics, as it should make this much easier to answer. Commented Mar 6, 2017 at 21:45
  • Engine = gas/diesel fueled, pistons, crankshaft, carburetor, oil changes, ......... Motor = electric fueled, windings, slip rings, squirrel cage, armature, brushes, wiring diagram, etc. Commented Oct 30, 2017 at 18:51

1 Answer 1


I'm going to go with an educated guess here and say these are condensation drains. This is based on two things:

  1. These holes are on the bottom. Usually when they are lubrication holes, they are on the top of the motor. (I'm guessing you have the motor upside down so you can take better pictures of it? If not, please correct me.)
  2. Location, location, location. The points which get lubricated on motors are usually the bearings. The bearings are located on the two end caps. If these were indeed lubrication ports, they wouldn't be located to the inside on the body of the motor.
  • 1
    And also, on the label it says "pre-lubricated ball brgs"...
    – Solar Mike
    Commented Mar 7, 2017 at 8:24
  • @SolarMike - It's the little things, eh? Thanks for pointing it out! :o) Commented Mar 7, 2017 at 14:09
  • There is nothing that 100% says which side is up, as it could be attached to a ceiling or wall as easily as a floor. But the main sticker is aligned such that the plugs face down, with respect to it.
    – Jonathon
    Commented Mar 8, 2017 at 13:03

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