Air Compressor Motor

[Bill D 2,355]

I need a new motor for my air compressor.   Turned it on yesterday and it started smoking.  I got the compressor used, and it's 21 years old, so I guess its about time.

 

Found a good price online from a place called Electric Motor Warehouse.  $399 plus tax and free shipping.  Anyone here familiar with them?   @Pullstart?  Thanks.

 

Bill

[Pullstart 68,055]

I have not used that company before Bill, but $400 for a 5 hp motor sounds like a pretty good deal!  Is the replacement also an A.O. Smith?  In water heaters, I’d never recommend that company… but for electric motors they seem to be everywhere for a reason!

[Bill D 2,355]

20 minutes ago, Pullstart said:

I have not used that company before Bill, but $400 for a 5 hp motor sounds like a pretty good deal!  Is the replacement also an A.O. Smith?  In water heaters, I’d never recommend that company… but for electric motors they seem to be everywhere for a reason!

The replacement is a Century Motor, I don't see the AO Smith label on it.  Looks identical. 

[953 nut 61,985]

Just be sure the frame number is the same, not all five HP motors are the same.

 

[ri702bill 9,984]

Bill - one thing to check before investing $$$ on that unit.

What condition is the pressure vessel (tank) in?? Any signs of rust around the bottom from trapped moisture inside?? Take a good look around the drain.

Replacing a compromised tank is quite expensive....

[Bill D 2,355]

8 minutes ago, ri702bill said:

Bill - one thing to check before investing $$$ on that unit.

What condition is the pressure vessel (tank) in?? Any signs of rust around the bottom from trapped moisture inside?? Take a good look around the drain.

Replacing a compromised tank is quite expensive....

Thanks.  I've thought about that too.  I've been able to look in the tank and found nothing serious.  Pump works fine.  I'm comfortable throwing $400 at it.  The cheapskate in me would love to find a good used motor, but that's unlikely.

[ri702bill 9,984]

Another possibility - HFT has a 3 HP 230 volt NEMA 56 motor rated for continous duty, ie compressor.

I used the 2HP 115/230 one on my milling machine, after the original suffered a "thermal event" in the connection box. Mine was not a direct bolt in - OE was face mount, HFT was foot mount like yours. The OE was available for $1200, the HFT was $200. A little fabrication, it outperforms the OE.

Edited October 9 by ri702bill

[Bill D 2,355]

Spoke to my local motor shop.  I could bring it to them to see if it's repairable, but there is a $75 charge to look at it.  I'm going to risk $23 on new start and run capacitors before I buy a new motor.

[lynnmor 8,060]

3 hours ago, Bill D said:

Spoke to my local motor shop.  I could bring it to them to see if it's repairable, but there is a $75 charge to look at it.  I'm going to risk $23 on new start and run capacitors before I buy a new motor.

If it has a centrifugal starter switch, replace that as well.

[Bill D 2,355]

I put new capacitors in it and it's running fine now.  Centrifugal switch in the motor seems to be fine.  I'm trying to avoid taking the motor apart.  If something else fails it's time for a new motor.  It's 21 years old.

Edited October 15 by Bill D

[Wayne0 1,336]

Most of the time that is the problem with cap start motors.

[Bill D 2,355]

42 minutes ago, Wayne0 said:

Most of the time that is the problem with cap start motors.

It was actually the run cap that was bad.  Start cap was fine.  The motor did start smoking for about two seconds before I shut it down.   Not sure how much life is left in it now as a result of it overheating.   If anything else goes wrong I'll put a new motor on it.  It's already 21 years old with unknown hours. Pump is still good and so is the tank.  Pumps the tank up from 0 to 125 in 4 min.  Recovery from 90 to 125 is about a minute.   

[lynnmor 8,060]

It might be a good idea to change the compressor oil and see if there is any metal in it.  I had a piston seizing causing intermittent overload that seemed like a motor problem.

[Bill D 2,355]

42 minutes ago, lynnmor said:

It might be a good idea to change the compressor oil and see if there is any metal in it.  I had a piston seizing causing intermittent overload that seemed like a motor problem.

Pump seems fine.  It's due for an oil change anyway.   Good time to check for metal.

[Bill D 2,355]

Anybody use Amsoil in their air compressor?  Expensive, but I'd like the pump to last for awhile.

Edited October 17 by Bill D

[R Scheer 505]

I haven't tried the amsoil, but I am using Dewalts synthetic compressor oil.  It's supposed to be 30w equivalent but has anti foam ingredients to make the compressor happy.  The compressor seems to run quieter and cooler,  but I haven't made any measurements to prove this.

Edited October 19 by R Scheer
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[Lee1977 7,369]

I had to replace one of the capacitors on mine year or back. I took it down to a local electric shop they checked it out thought it need a new capacitor. Said I would have to pay for the capacitor if it didn't run.

I took the chance and and they hook it up and it went back to work,. I think the capacitor about the same price as yours. Old shop it has been there as long as i can remember.