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Harbor Freight – won’t build pressure past 20 psi. It ran fine 12 hrs. prior.

by Don
(Fort Walton Beach)

I used it pm, it is like new few hours use, I left it plugged in turned off valve, next am heard it running, opened garage noticed oil on floor, unplugged pancake compressor.

Harbor Freight pancake style air compressor
Harbor Freight pancake style air compressor

I noticed their was no air in tank. Now after I refilled oil , it wasn’t empty, The compressor works but air won’t build, It is like a safety pressure switch opened up, although the pop off valve is working and is closed? Is there another safety? Or is there a component failure?

This is a oil type pancake 100 psi unit I bought from Harbor Freight. Why did it spew oil? It seemed to come from the fill tube? The compressor is compressing.


Don, it sounds as though it might have overheated by running too long, and that higher heat might have cause the oil to spill out of the sump.

When you checked the oil, if it was almost full as you said, that wouldn’t have been the problem.

You are on the compressor will not build pressure page. What checks did you perform to try and determine what has failed on your compressor? Surely, something has let go, possibly heat related, and once you do the checks, you’ll be able to better pinpoint he cause.


Harbor freight pancake compressor
by: don

Thanks for the response, although something blew air wise first , then compressor ran without enough pressure to trip the automatic shut off switch, and causing the heat and oil release. ? What component would release the tank and stay open? To cause the compressor to run all night? I checked the safety release and it is working as designed, and was closed. Something in the box near the hose connection? The hose’s were intact so it wasn’t a popped air line? I haven’t looked into it any further, I was hoping for direct advice first. Can I used 30 weight ND oil for the compressor?

An item that can jam open and possibly drain the tank too is the Unloader Valve. See that page for info on it. See the Oil Issues section on the site map page for info about compressor lube oils too.

More info? Add a comment please.