air compressor breather 'smoke'

turbodog

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Have an air compressor that has a slight 'smoke' coming from the breather tube after it runs for a few minutes. Has done since new (3 years)

Cylinders will be barely warm, heads will be fairly hot but not too much so. Oil is new and in proper fill range. Does not get worse when I really work it for an hour or more straight running. No weird noises or other indications of failure. Oil level steady... not dropping.

Ideas?

I'm thinking maybe hot gas blowby that then condenses into 'fog or 'smoke'...
 
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bigburly912

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By any chance is it a Quincy?


Oh and does the smoke smell burnt or does it just smell like oily smoke?
 

TILL-22

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I think that's pretty standard across the board. I use a vacuum pump that also does it since new and the smoke colour hasn't changed after oil change.

Maybe try searching for the specific model and frequent issues just to be sure.
 

turbodog

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I've got a clear line through the wall for the drain. Every time I turn the drain valve I see a flash of orange water fly through the line at 100 mph. Handy tip... don't stand out back during this time.
 

bigburly912

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At one point on garagetalk a fellow had a Quincy QT-54 that did the same thing for no reason. People thought rings, intake reed but nothing really fit the bill because the oil wasn't burning and there was no milky white drain water. (Sign of bad rings)

Anyway, the fellow ended up getting a new pump and the tech that came out gave no real answer. At first Quincy was gonna give him a whole new unit just for the trouble!

If it doesn't smell burnt then it has to be blow by. The crank case may be just slightly overfilled.

Quincy recommends running their compressors for something crazy like 100 hours without a load for break in period, that's insane.
 
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turbodog

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I did about 8 hours... think that's all this one called for.

I don't have oil in the air nor in the tank. Not using oil... has to be humidity I guess?
 
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