Richard wrote in: ” I have a craftsman 3-gallon, 1 hp, oil lubricated compressor with a sight glass for oil level. I filled it to proper level in sight glass (the top of the red dot) and used it once. Worked fine. Then it got tipped over and a little oil ran out the air filter. Now the oil level in the sight glass says it is overfull (actually completely full because there is no bubble to indicate oil level.) Have not turned it on since. I need to know what I should do before using it again. Will running it in this condition cause a problem? If so, what should I do to rectify the situation?”
I Tipped The Air Compressor Over
A few things need to be considered here, Richard and they apply to most any oil lubed air compressor.
“A little oil ran out of the air filter”. This happened because there has to have been some oil in the compressor pump cylinder over the piston, and the only way that could have reached that point from the sump under the piston is if the piston seals were allowing lube oil to bypass the piston. So, if this is a new compressor under warranty, that in itself is a reason to return it.
I expect that this compressor has a bunch of hours on it… yes? In the complete rebuild replacing the piston seals would be something you should do.
According to my understanding, the proper fill level with an oil lubed air compressor that has a sight glass is to the middle of the dot that is in the middle of the sight glass. That you filled the oil to a level equal to the top of the dot likely isn’t a big issue, though it does mean that the lube oil is approaching the overfill level, and overfilling the sump leads to compressor problems in it’s own right.
“No bubble to indicate oil level”. There’s typically not a bubble. Air fills up the sump until the level is visible, and as mentioned, you stop when the level reaches the middle of the dot in the center of the sight glass.
I suspect what’s happened here is that the oil, very viscous oil (sticks to everything) has coated the inside of the sight glass, and will not easily disappear. What I suggest is that you, with care as oil will come out, remove the plug under the sight glass and let all the oil drain out into a container.
Examine the oil. If it looks clean, and you can remember when you last did an oil change, consider reusing it. If this were mine, I’d safely dispose of it and use fresh oil.
The sight glass should be able to be screwed out of the sump housing. Do that, and clean the inside face of the sight glass. Replace it. Then, fill the sump to the middle of the dot.
What about the oil in the compressor cylinder?
That may be an ongoing issue. Oil from the sump is not clean, containing bits of metal debris etc. Whether or not the pump needs to be disassembled and cleaned is not something I can decide from here.
There is a bit of a risk using the compressor without dismantling the pump and cleaning out the area over the cylinder. Your call whether or not you do.
If you choose to go ahead, and if it were my compressor I would, after the oil level is correct with fresh oil, I’d start it up and see what’s what.
If you follow this advice and do so, would you mind leaving a comment on this page telling us what you found? Good luck, and thanks for writing in.