View Full Version : Lubeing an Electric Motor

06-04-2012, 10:10 PM
I picked up an old wood planer the other day. The motor Is a 3 hp Marathon 110/220 VAC. It is TEN inches in diameter. It must be an honest 3 hp. ;)
The motor turns free, but I doubt it has been lubricated in the past 40 years. The bearing housings have slotted screw covers that are threaded similar to Alemite fittings. I can't tell if the lube is oil or grease.
Does anyone have a suggestion as to the proper lube to use?



06-04-2012, 10:14 PM
Check that the bearings haven't been replaced with shielded or sealed sometime in the past.

If it has the orginal bearings and oil cup fittings, 20W non-detergent is typical. Grease access point can either be for the bearings or just to put grease in the gap between the bearings and the shaft at the end cover (to keep moisture/dust out).

if you desire, sheilded bearings are cheap and easy to replace.

Forrest Addy
06-04-2012, 11:20 PM
Careful. It's an old motor. It might be ball bearing but it may be sleeve bearing. When sleeve bearings were employed they use an oil reservoir and wick. Another option was oil reservoir and an oil ring - a loose ring which rode the shaft around to dip in the reservoir and drag up oil.

The motor is old. It's probably a good idea to open it up to vacuuming the windinga. At that time look at the bearings - ball or sleeve - and procede as required. BTW, ball bearings? 40 year old grease is 40 years old. A bare metal cleaning and re-pack is probably a great idea.

06-05-2012, 03:02 AM
Look again and see if that bearing housing has such a plug top and bottom. If so the plugs should be removed and the top one replaced with a grease fitting. With the motor running add grease at the top until clean grease exits the bottom. Replace the plugs and you are probably good for the next ten years.

06-05-2012, 09:53 AM
I have an ancient "Leland" motor with those brass bottom plugs , always wondered what they were for. The top has no plugs, instead it has "Gits" oil caps.
These motors are really built to last , the bearing/bushing housing on each end ,(i ,m pretty sure these are bushings, ) has to be at least 2 inches long.

Well built stuff.

06-05-2012, 10:21 PM
It looks like you get the prize. I didn't notice the bottom plugs. Any special grease or just standard bearing grease?

Thanks for all responses.


Ohio Mike
06-05-2012, 11:43 PM
Mobil SCH-100 Electric Motor Grease

Enco Part No 505-1239