Oil in tank when draining condensate

by mike
(ohio)

I have found oil in the bottom of my Campbell Hausfeld 60 gallon tank when I drain the condensate.

Basically its just a few drops. When checking things over, I found that if I put my hand over the breather on one cylinder it has suction. The other cylinder doesn't. Any thoughts?

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Bill says...

Hey Mike, nice to hear from you.

An oil lubed compressor uses lubricating oil to allow the mechanical parts to run freely. That oil is often "splash lube" meaning that it's the movement of the system parts themselves that move the lubricant from the sump up onto the items to be lubricated. Or, in larger systems, there's an oil pump that does the same thing, in much the same was as the oil pump in your car works.

That oil gets up under the piston and onto the cylinder walls.

The piston rings align the piston, provide some lubrication function depending on the type, are a wear element, and also wipe the cylinder walls, this to keep the oil from below the piston from getting up into the air that's being compressed.

Despite the best efforts of the rings, there is some wicking of oil up the cylinder wall, and I suspect that it's this oil that's getting into your tank.

A few drops in the drain water are to be expected, and shouldn't be cause for alarm. An increasing amount of oil should set off your alarm bells as this may indicate that the piston rings are wearing, and in time, if not repaired, the piston may score the cylinder wall, a whole new issue to deal with.

As to the lack of suction in the cylinder, when the piston drops down - or retracts - inside the cylinder, a valve in the cylinder head should open, allowing free air into the cylinder. When the piston compresses - moves up - that valve should close, thus forcing the air into the flow path to the tank.

If your cylinder port isn't pulling in air when the compressor is cycling, I think that you've either got a bad valve (plugged - dirty - jammed - broken etc.) or the piston rings are worn to the point where air isn't drawn in on the retract of the piston, or, you've got a gasket failure somewhere in the head.

If you aren't comfortable with tearing down your compressor, you might consider visiting the Repairs page to find a repair depot near you.

Cheers,

Bill