Question about Dewalt Heavy Duty 2 Brad Nailer Compressor Combo Kit

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Central Pneumatic 94667r 3 hp electric oiled compressor

Will only build to 20 pounds of pressure and refuses to go any further. It builds to 20 pounds quickly but no further. I let it run for over 20 minutes and it never went past 20 pounds. This is the first time I have tried to use this unit as I just purchased it 'as-is' the other day. I followed all the instructions in the manual. I did notice that the sound of the compressor is slightly different once it reaches 20 pounds. It reminds me of a pop-off valve coming into play some way, but I have no basis for this other than a gut feeling. One other odd thing is that there is quite a bit of air flowing out the oil fill cap when it is running. Maybe a back-pressure leak ?? Thanks for any guidance.

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Sounds like your check or reed valve is bad. when the piston pressurizes and pushes air into tank the pressure should not be able to come back into cylinder and thsi is what its doing and then that pressure is now going past rings into oil. look for the valve before the tank. a check valve.

Posted on Apr 23, 2009

  • just2tall65 Jan 05, 2011

    i have the same problem as daniel9913. my central pneumatic compressor keeps running but builds no more pressure once it reaches about 22 psi. where is this check or reed valve located?


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The diaphragm at the bottom of the black power switch box has a split in it. Remove the top of the black power switch box by removing the single philips head screw accessible through the hole next to the red switch knob. The switch/diaphragm can be removed by taking off the 4 bolts at the base of the switch. Using model # call Harbor Freight for a suitable replacement switch and gasket. I haven't been able to find the gasket by itself.

Posted on Nov 03, 2011


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Posted on Jan 02, 2017

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