Compressor motor diagnosis assistance, please.

[KinzeMech]

I have a 60 gallon, single stage, craftsman air compressor. It has a devilbiss pump on it. It has given me a fantastic service life, until yesterday.

It starts, and runs, ok, but within about 15 seconds of starting up, begins to emit smoke from the motor. Opening up the motor found several mud dauber nests in it (of course). One in a position that could have obstructed the start switch.
Removing the mud dauber nests had no effect. It still emits the smoke after a short period of time.

Is there anything to check before determining this motor to be unsalvageable?
My repairs of electric motors has been limited to bearing replacement, repair of faulty electrical connections, and capacitor replacement. If it's possible this could be a capacitor, or capacitor switch issue, I may be able to do something about it, but if it's in the windings, this thing is probably junk.

It uses an oddball pivot mount motor, so I can either pay the inflated price for the special motor, or invest time in fabricating a motor mount adaptation to this compressor, if it comes to motor replacement.

 

[Davefr]

It starts, and runs, ok, but within about 15 seconds of starting up, begins to emit smoke from the motor. Opening up the motor found several mud dauber nests in it (of course). One in a position that could have obstructed the start switch.
Removing the mud dauber nests had no effect. It still emits the smoke after a short period of time.

What you describe is a sympton of the start winding staying energized after the motor is up to speed. The motor will run very hot and eventually the start winding could burn up.

Take another look at the centrifical switch and/or starting circuit.

 

[bran1har]

DaveFr gave perfect advice, do that, but don't let is catch fire or the laquer on the winding will be toast.

 

[KinzeMech]

I think it's too late.

The start capacitor switch had a contactor burned up, and the switch assembly had welded itself shut, so the startup capacitor/windings were staying energized.

I disconnected the line feeding the startup capacitor by pulling it's wire off the junction board at the switch, and started the motor (no load) without the use of the startup circuit. Even without the startup circuit energized, the motor began emitting smoke within about 30 seconds, so while this problem started with the startup circuit, it looks like it has now damaged the windings, which puts repair of this motor outside the reach of my skills.

Thanks to those who offered diagnostic advice.
I suppose now I am off to shop online for the best replacement for this oddball motor.