Old GE motor - is 130F overheating?

[Tereci]

Hi,

I have an old GE 5XBH00D D motor with 1/3HP 6.8A 1725RPM on a used lapidary saw I recently bought. The saw is from the 70ties, not sure about the motor. I noticed that it's getting pretty hot while running. It gets to 125F in about 5 minutes when running even without any load (without a belt attached).

According to my friend who has a bunch of lapidary equipment this seems to be too hot especially with no load. I figured I'll get another opinion before I start fretting about it. Anybody knows if this temperature sounds ok or not and what I could do about it?
The only thing I did to the motor after I bought the saw is dripping a few drops of zoom spout oiler into the oiling ports and replaced old power cable.

I'll attach some pictures.

Thank you,
Tereza.

 

[ramsy]

The only thing I did to the motor after I bought the saw is dripping a few drops of zoom spout oiler into the oiling ports..

The Nameplate says "REOIL WITH SAE 10"

What SAE is zoom spout oiler?

 

[Tereci]

It's some super light oil that was recommended to me on this forum for this motor previously. It doesn't have SAE marking on it. It says "Zoom Spout Oiler. Finest all-purpose oil. Good for cooler bearings, motors, ..."

This one https://www.homedepot.com/p/DIAL-4-oz-Evaporative-Cooler-Zoom-Spout-Oil-5714/100128593

In comments on home depot somebody asks about the weight of the oil and the reply is "It is equivalent to a 10 weight, non-detergent oil."

 

[LarryFine]

It says "Good for cooler bearings ..."

Does that mean for bearings in coolers or for cooler-running bearings?

 

[Hv&Lv]

That doesn’t sound high at all.
UL says 158 degrees for stuff like bench grinders, saws, etc. stuff you would normally touch while using it.
a general purpose motor should be designed to run hotter than that

 

[paulengr]

No fan. I’ve seen large industrial motors easily up in the 200-250 F range. If it blisters paint or the oil gets burned it’s too hot.

Often on single phase motors running hot is a sign the run capacitor is starting to fail. As it does the power factor drops so the motor pulls more amps and runs hot. Or it could be early signs of bearing issues. Either way in this size diagnostics is more expensive than replacement.

 

[Jraef]

How do you know the temperature? Are you using an infrared gun? If so, see if the end with the sheave (belt attachment) is hotter than the other end by a great amount (+10% or more). If so, it could be an indicator of the belt being too tight or the bearings going bad.

"Hot" is a subjective term though. In general, small cheap motors like that would likely be using what's called Class B internal winding insulation and we assume worst case that it has a 1.0 Service Factor, would be rated for a maximum temperature RISE (over ambient) of 80 degrees C, plus a 10C "hot spot" and if we consider ambient as 40C , the windings can get as hot as 130C (which would be 266 degrees F!). As a general rule, the surface temperature on the outside will be 30C lower than the interior, so 100C, which is 212 degrees F. Bottom line, unless the surface is above 200F, I would but get too worried.

 

[Tereci]

@Jraef Yes, I am using infrared gun. I'll check the temperature in the different spots as you suggested, great idea, thank you!

I ran the motor for a longer period of time and it seems to stay around the 130F so hopefully that is good.

Thank you all for your help!

 

[Jayd3]

If shaft turns freely and it's not heating more as you run it no load or with normal load I'd just run it. If bearings or rotor are draging then you need to fix what is draging. Dont over oil use 10 drops of in each port is the rule of thumb.