Thread Number: 46090  /  Tag: Pre-1950 Vacuum Cleaners
Mid 1930s Hoover model 25 Motor Smokes 		[Down to Last]
Post# 475512   2/11/2025 at 12:25 by vacuumheaven05 (Frederick, MD)        

Hi there, I recently acquired and restored for the most part, A mid 1930s Hoover model 25. It has the original wheels, bumper, and rubber handle grip which is brittle. It has a factory original bag and cord from a hoover model 28 which are both in mint condition, but it's close enough.
Unfortunately, since I tried to service the motor and lubricate it to spin freely, whenever I run the machine, the motor tends to smoke a lot, within 10 or so seconds. The thing is that, even though it seems that the vacuum runs at pretty much normal speed and the brush roll spins freely without issues, the motor still smokes. Even when I unhook the belt from the fan shaft and run the machine for more than a few moments, the motor still smokes, and I immediately notice a burning electrical smell.
It's a shame because I serviced the motor by lubricating and oiling the armature shafts and bushings in each bearing. Though the armature and fan spin freely, the motor still smokes, so I now think that somehow the windings in the armature shorted out. If that's the case, I don't know where to get a replacement armature, which has intact windings. Either I'll end up finding a spare hoover 25 motor that runs good, or I'll have to get the entire armature rewound. I don't know if someone has a spare hoover 25 motor that runs good, that can be for parts. I'm not really sure what the best thing to do is at this point?

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Post# 475515 , Reply# 1   2/11/2025 at 20:10 by Hoover300 (Kentucky)        

hoover300's profile picture
Did you by any chance run this backward?

Also those motors use grease not oil.

Post# 475527 , Reply# 2   2/12/2025 at 19:49 by vacuumheaven05 (Frederick, MD)        
Reply

 How does one run a vacuum, such as my hoover 25 in reverse? Do you just simply plug the cord into the outlet in reverse, or the opposite way? I'm not sure

Post# 475529 , Reply# 3   2/13/2025 at 03:56 by kirbyklekter (Concord,Ca.)        
Smoking motor

 I'm wondering if you might have gotten some oil on the windings, or maybe over oiled and it's getting there while running, possibly on the carbon brushes too. I would inspect the armature and wipe it down if it appears oily with alcohol or contact cleaner, making sure it's dry with no residue remaining before running it.Hopefully that's all that's making it smoke. Good luck!

Post# 475537 , Reply# 4   2/13/2025 at 11:50 by vacuumheaven05 (Frederick, MD)        
I'm Wondering

 I did put oil on both parts of the armature which fit through both bushings of each bearing. Is there supposed to be any oil at all in each bushing or is adding oil to the bushings the direct cause of why the motor is smoking? The thing is I do know that both bearings in my hoover 25 are ball bearings, However, they are sealed bearings, meaning they cannot be repacked with grease. Maybe because I added oil to the bushings, some of it may have gotten on the windings, which is causing the smoking. Is one supposed to add oil to the bushings in those sealed bearings, or are the bushings supposed to be completely dry? Nonetheless I will inspect the armature and try to remove and clean up all oil in the motor.

Post# 475538 , Reply# 5   2/13/2025 at 11:52 by vacuumheaven05 (Frederick, MD)        
Something to mention

 Would cleaning the armature shafts with WD-40 work for removing oil residue, besides alcohol?

Post# 475605 , Reply# 6   2/17/2025 at 06:12 by kirbyklekter (Concord,Ca.)        

Are you removing the armature to clean the windings? If so ,there are many products you can use. I've heard people use liquid dish soap like dawn or grease removers like 409 or simple green. Contact cleaners for electronic equipment like stereos or circuit boards etc would work. You don't want to use anything that could melt the protective coating on the wiring on the armature or the field wires. It should be easy to remove any oil that got there since it would be fairly new, it's not like your trying to remove old baked on grease from an oven!

People use WD40 for a lot of things, I don't know if it works for cleaning wiring. I was told it was originally formulated for the removal of moisture in locking mechanisms. It's not the first or second thing I'd reach for. Don't forget to check your carbon brushes for any oil that may have reached them.

On bearings that were originally greased I don't try to use oil as doing so will thin out any existing grease causing a messy leak and a bearing failure.

Post# 476131 , Reply# 7   3/19/2025 at 12:13 by kirbyklekter (Concord,Ca.)        
Smoking Motor

 Have you made any progress with the smoking motor? If so can you share what the problem was and what you did to correct the situation? Thanks!


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