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My air compressor is running, but there is a little bit air

I have a 125 PSI Craftssman air compressor, which is 1HP / 12Gal, for one year. I used it for nailing the doors and windows molding last Summer, and I left it in my strorage. Yesterday, I used it to blow the dust that it still had about 40 PSI in the tank. I turned it on, and it ran okay. After 30 minutes later, I checked the pressure gauge, the pressure gauge hand still stayed the same pressure as it was( 40 PSI ). Then I let it run another hour, and I came to check it again. It's still the same result. There was no leak. Therefore, I would like to know what is wrong with my air compressor?

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  • rjake Nov 18, 2008

    I have a Craftsman 125psi/3 gal/1HP air compressor that builds pressure to 20 psi and no more. The oil is good, no obstructions and the motor keeps running. What can I do?

  • skajaquada Jan 19, 2009

    I also have a crafstman compressor, but 60 gal type. It will only pump 92 psi into tank. Just runs and runs, never building enough pressure to fill tank completly. Pulled pump apart. replacing gaskets. Rings and cylinder walls look perfect. No leaks anyplace. Any help out there?

  • Anonymous Mar 26, 2014

    I think I ran the rental compressor we have out of diesel gauge says it's low but it's on a bit of a slant. It is a caterpillar 375 cfm unit is there a primer and if so where would it be



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Pistons may have lost their seals and not compressing the volume it needs. It's not turning off at 40 correct? That would be the pressure switch. Oil lubed probably like taking a small gas powered engine apart. Check the walls for scoring and such. If none to deep you can get an attachment for a drill to hone them. Auto parts will have that, parts depend on how old but should be at if you have like Sears Appliance repair stocks many different parts for what not. VERY expensive to let them do it but is an option for you. Make sure you have specs for torque and such for the bolts. And your sure no leak or pressure relief valve, yea you would hear that. I wish it was something else.But that's all I can think it would be if it's running continuously.

Posted on Nov 20, 2008


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