Thread: Air compressor got water in the oil

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I have a small dayton 2 cyl compressor that had ran for 24 hrs with a water leak spraying right on top of it. It got so hot it burnt and broke an exhaust valve which I have repaired with all new valves. Compressor runs perfect now but the crankcase oil was milked from sucking in water vapor. I've drained and refilled twice but I'm having a hard time getting all the milk to disperse off the cranckcase walls.
So my question is, does anybody have any suggestions of something I could add to the oil to help with breaking up the moisture. It only uses a half qt. of non-detergent compressor oil. Thanks for any suggestions.

Unless you can get the crankcase hot enough to burn off the water, I'm thinking you just need to keep replacing the oil on a frequent basis until the milky color goes away.

Originally Posted by 34_40

Unless you can get the crankcase hot enough to burn off the water, I'm thinking you just need to keep replacing the oil on a frequent basis until the milky color goes away.

Yep, I'm thinking the same as you. I may do some fill and run time with some regular detergent motor oil and see if it helps to disperse the milky coating off the crankcase. Just looking for something to speed the process. I was thinking along the line of adding a bit of Marvel Mystery oil or something to help clean it up. The compressor oil is seven bucks a quart and I don't want to put it in service until I know the crankcase is clean. Its likely pretty sticky because it sat for over a year before I decided to repair it and give it to a friend. Crankcase barely gets warm after running for an hour or so. I may open the drain bleed and let it run for a few hours to get the crankcase hotter.

I honestly don't think I'd worry about it a whole lot. Put in fresh oil and run it, depending on the amount of runtime.. change it in 3 to 6 months.. then rinse & repeat.

Might be a crazy idea, but what about pulling the drain plug, letting it drain for several hours and then blowing some hot air through the oil filler, out the drain with a hair dryer or a heat gun on low? Just thinking that it might cook off a little of the moisture before you fill it again. I agree, I don't think I'd worry with it much.

You could always tear it down and overhaul it, but I don't think that's necessary. If it's building and holding pressure, and not knocking or making weird sounds, just put new oil in it and go, change the oil more frequently than usual - usually once a year under normal industrial use - for a while, I'd say every four months or so, and it will likely be fine.

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Thanks for the replies, I got it cleaned out now. On the third oil change I added about an ounce of MMO and the oil came out alot cleaner, then on the fourth change it drained out nice and clean. Filled her up with fresh oil and called it done. Just for general info, I started with buying quarts of compressor oil @ 9.99. I found a gallon @ O'Reily's for 12.99. In the past I used to buy straight 30w non detergent for compressors but you can't find non detergent oil anymore. Oh, I did stick an air nozzle in the fill hole on the last drain and it helped in pushing out all remaining oil. Thanks

Just a quick tip about water in oil in any application---
since water and oil DON"T mix ( yes they do become milky) a good way to start is to tip whatever its in to where the drain plug is the lowest point-------------after a while ( maybe several hours/days?) carefully take the drain plug out slowly letting the separated water to drip out first-may take a few times but not much reason for over spending $$$$$$$$$to change expensive oil several times.

Thanks for the end of the story. The good thing is that since it only holds 1/2 qt of oil you didn't spend too much of your Christmas money, and by finding the gallon at O'Reilly's you've got enough in reserve for the next five or six years Glad you got it done!