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Brand New Motor never ran, but has a rusty rotor and stator coils

Isaiah4110

Plastic
Joined
Dec 5, 2023
I was given a brand new motor that has unfortunately sat outside for multiple years. It still spins freely but has a bit of a "Crunchy" sound while spinning. I took it apart to find a good bit of rust on the Rotor and the Stator coils. Everything else looked really good.
Question for the community..
Can you lightly sand with some very fin grit sandpaper to get the rust off? Obviously one needs to be very careful around the laminated wire coils, but how about the surface of the rotor and and inside on the metal of the stator?

Been doing some reading on some of the forums and this seems to be acceptable. I would like to clean it up and maybe donate it to my University. I imagine it runs just fine.

Any words of caution or wisdom would be much appreciated. Merry Christmas.
 

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You can remove the rust as you describe. ScotchBrite pads are easy and less likely to score the wires. Light rust that isn't flaky or loose isn't a huge problem anyway. Sometimes the laminations are also laquered but that's already gone if they've rusted.
 
We had a refinery customer who had a 14,000HP 3600RPM motor...very finely built to the highest standards. The big flood came during one of the hurricanes, and the plant was shut down for a couple months while they cleaned up all the mess. Once they started back up, they called and said the motor was vibrating a good deal 'all of a sudden'. After some questioning, they assured us the motor had not seen any flooding so they sent it back for inspection and fixing. Once it arrived...we could clearly see a water line inside about halfway up the motor. Hmm. Pulled it apart and the rotor had rusted pretty heavily on the lower half. Unlike the low voltage motor shown above, there is no way to clean rust of of all the cooling slots and vents. New $650K rotor needed.
 
You can carefully remove the rust, but the bearings are the only thing that matters. If it runs, it will be ok. There are new motors with more rust than that.
 
Brush on some phosphoric acid on the rust areas. Works like nothing else.
I use EdFed from Ace Hardware. What I see in the picture is no big deal.
 
Yep, I see the rust on the bearing shield.
The grease inside the bearings may have inhibited rust inside.
Give the two bearings a twirl and listen for your crunch sound.
 








 
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