What if I don't put in enough oil after I change the oil?

by Michael Panza
(Leesburg, VA )

I changed the oil in my Craftsman Model No. 921-153101 Air Compressor 3-gallon 1HP Oil Lubricated Air Compressor using the instructions provided by the manual.

I made sure that all of the old oil was removed.

I then refilled it using the oil that came with the air compressor up to the sight glass as stated in the manual. It seemed to take less oil than what I took out. I started using it and it worked fine for about 15 minutes give or take a few minutes.

I read a strange sound and immediately turn it off, but I did not check the oil level. I did not notice anything wrong, so I turn it back on, and then it just completely turned off by itself.

It is at this time that I noticed the oil was low and added more oil until it was the middle of the sight class, but it would not start. All it does is hum, but it will not start. Any suggestions?

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Bill says...

Michael, if the humming is related to a low oil condition, this may mean that your pump parts have changed somehow (warped) to the point that the motor cannot overcome the added load. If the motor hums for too long, it will overheat, and likely cause damage to the motor.

I'm not sure how you can fill the oil to the correct level, start the compressor, and have the oil level fall to a critical level.

Certainly, when I fill the oil to the correct level on my compressor, the oil level stays at the fill line for some time, until the oil is consumed or leaked out. (cheap compressor :-)

If no other conditions at or near where you use your compressor have changed (other items using power for example) you may have created a problem by running the compressor at a too low oil level. It's probably time to take it to the shop.

Sorry,

Bill