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Air compressor motor overheating - any thoughts to fix?

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Forum topic by Planeman40 posted 11-02-2017 12:38 AM 3331 views 0 times favorited 11 replies Add to Favorites Watch
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Planeman40

1201 posts in 2842 days


11-02-2017 12:38 AM

Topic tags/keywords: electric motor

I have a 2 HP tank-type air compressor with a capacitor start electric motor. I bought the compressor (for home workshop use) way back in early 1970s from Sears. It runs fine, but lately after about 15 min. of use it quits. The “overheat” button on the motor pops out. After letting it cool off, I can push the “overheat” button in until it clicks and all is well for about another 15 min.

Nothing seems wrong with the motor. But it does have some cooling openings. I am wondering if over time the coils have accumulated a lot of shop dust. I hate to open the motor up without some sense of what the problem may be.
Any thoughts from the gang here?

-- Always remember: It is a mathematical certainty that half the people in this country are below average in intelligence!


11 replies so far

View MrUnix's profile

MrUnix

6845 posts in 2280 days


#1 posted 11-02-2017 01:53 AM

Given the age of the machine, I would suspect bad bearings. I would also check the air inlet filter to make sure it’s not clogged. Since I don’t know the type of compressor you have, bearings inside the compressor may be suspect as well. The thing is 40+ years old… well overdue for some maintenance if you haven’t given it any in all that time.

If you suspect it may be clogged up with sawdust, opening it up and checking would also be the best time to check the condition of the bearings. Just saying.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

View playingwithmywood's profile

playingwithmywood

424 posts in 1678 days


#2 posted 11-02-2017 02:29 AM

it could be lots of things but I would check the check valve

View tomd's profile

tomd

2164 posts in 3851 days


#3 posted 11-02-2017 03:00 AM

Blow it out with compressed air and see if that helps.

-- Tom D

View bigblockyeti's profile

bigblockyeti

5170 posts in 1802 days


#4 posted 11-02-2017 12:00 PM

Blow the motor out good with compressed air to start. If it’s belt drive, remove the belt a d see if the motor and pump both turn freely. If it’s an oil lubed pump, when was the oil last changed? Do you have access to an ammeter to check the motor current draw loaded and unloaded?

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JCamp

785 posts in 632 days


#5 posted 11-02-2017 12:53 PM

probably a dumb question but is the oil level correct?

-- Whatsoever thy hand findeth to do, do it with all thy might

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Planeman40

1201 posts in 2842 days


#6 posted 11-02-2017 03:06 PM

I guess I will try blowing the motor out first. If that doesn’t work taking the motor apart will be next. I hate the thought of that. I kinda doubt it is a bearing problem as everything turns smoothly, but could be. It seems the care and upkeep of a shop is eternal. Sigh . . .

-- Always remember: It is a mathematical certainty that half the people in this country are below average in intelligence!

View MrRon's profile

MrRon

4917 posts in 3325 days


#7 posted 11-02-2017 03:59 PM

It could be any of the above or it could be the “overheat” sensor is faulty. Try running the motor with the belt removed and see if it shuts down. Also check if the belt is tensioned correctly. Tension is correct if you can deflect the belt 1/2” at mid span. A belt that is too slack or too tight, can raise the current draw of the motor, causing it to overheat. A motor that is 47+ years old is usually a much more robust beast than the newer motors.

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Planeman40

1201 posts in 2842 days


#8 posted 11-02-2017 04:18 PM

Interesting thought Mr. Ron! I will do that.

By the way. I keep up with your posts. I find you and I are cut out of the same cloth. About the same age (I am 77), same interests in both machining and woodworking, and I would guess have about the same machines and shop. Your post about growing up reading Popular Mechanics, Popular Science, Mechanix Illustrated, Science and Mechanics (the last two only you and I would know about : ) are what I did as a kid. If you ever come to Atlanta, GA, please look me up. We need t get a beer and talk.

-- Always remember: It is a mathematical certainty that half the people in this country are below average in intelligence!

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splintergroup

2203 posts in 1303 days


#9 posted 11-02-2017 05:47 PM

I’m with Ron here. Do a good blow-out and check/lube the bearings and compressor, but these pushbutton thermal/load breakers do wear out and or shift in their trigger points.

My Powermatic 16/32 began popping its breaker almost every time I used it (after about 1 year of use). I replaced the device with a new one, same ratings, and it’s been perfect ever since.

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playingwithmywood

424 posts in 1678 days


#10 posted 11-03-2017 05:16 AM

again check the check valve the unload valve

View jbay's profile

jbay

2488 posts in 980 days


#11 posted 11-03-2017 04:51 PM

Is the motor running longer than normal to fill the tank?
Possibly bad reed valves, or piston rings are shot.
If that’s the case the motor would have to run longer, possibly causing the overheating.

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