Blue Flame on air compressor motor

[kaiserwill]

Hey guys, what would cause this: Turned my 60 gallon Kobalt air compressor on and thankfully I stayed in the garage because after a moment or two it made a weird hiccup sound. It did it again and I saw a small blue flame on the electric motor. It did it once more before I could shut it down. When I took the top cover with capacitors underneath, this is why they looked like. What would cause this?

 

[The Cobbler]

when capacitors fail or are failing they often swell like that . I am not sure why they do, but it's a sign they are toast.

 

[908Jim]

when capacitors fail or are failing they often swell like that . I am not sure why they do, but it's a sign they are toast.

I'm not a components engineer but I'm pretty sure it's gas pressure build up from the breakdown of electrolytes in electrolytic caps. I don't think ceramic caps fail like this. Hoping somebody on GJ can explain it to us.

To OP, I agree that cap is toast however I can't say for sure if it was the root cause or a symptom of another problem. If you're going to replace the failed cap, it might be good to replace the other one as well. Probably not far behind.

 

[driftpin]

I had something similar happen with a 'curbside donation' 60 cu. ft. upright 240V compressor, when I was trying to fire it up, and once I saw a brief flame, and the motor quit, I didn't bother anymore w/it. It went to an acquaintance's scrap business for disposal. It worked for awhile when I made the initial attempt to get it functioning, it built pressure going towards 80 psi, but then the blue flame visible from the cooling holes of the motor. I removed the 240V plug I'd bought for it, and drove it to the scrapyard. The tank was rusty on its exterior, the drain was dry. Win some, lose some.

 

[rlitman]

I'm not a components engineer but I'm pretty sure it's gas pressure build up from the breakdown of electrolytes in electrolytic caps...

Technically electrolytic caps are DC components, though there is an electrolyte in these AC caps. Anyway, internal arcing creates plasma that builds up gases and pressure inside. In the silver run cap, the terminal end is supposed to dome up under this pressure, tearing apart the connection between the terminals and the innards. Start caps work a little differently.

Did that start capacitor have a bleed resistor across the terminals? They often have one factory installed, and I'm wondering if that cooked.

 

[stonesfan68]

Now you know the meaning of the phrase, "The motor let the smoke out." The capacitors are toast. It should be a pretty easy and inexpensive fix. You'll need to read the labels of the capacitors and match them up to get the proper replacements.

 

[Retired dozer fixer]

What he said….the smoke leaked out

 

[Sniper60]

What he said….the smoke leaked out

The "Magic Smoke", lol