I have a C2006 Type 4 Porter Cable pancake compressor which will build pressure all the way up to 150psi then cut off as it should but there will be a loud hissing and pressure drop until the cut on pressure is reached then it will restart and build pressure to the cut off and repeat the whole process all over again. I can get the loud hissing to stop by manually turning the compressor on and off which will start and then quickly stop the compressor motor. However even after doing such pressure will have leaked down to zero over night. Why does this loud hissing continue after the compressor motor has stopped and why does the pressure still leak down? Is this the sign of a bad check valve or, regulator, or motor? Will either or all have to be replaced? Can either or all be cleaned or repaired? Thank you in advance for your assistance
Air Tools & Compressors - Porter Cable - C2002 150 Psi 6 Gal Compressor
Answers & Comments
First you have a reciprocating pump and the hissing you ear probably comes from the unloading valve on the pressure switch(it will look like a bike tire valve)if there is air coming out the valve when the compressor is off it probably means you have a bad check valve.This valve is use to unload the pressure inside the pump for an easy start .a motor always drive more amps on start up if you cant unload this pressure you will trip the overload(you probably have a reset button on your motor)check the specs on your pressure relief valve ,its a small pump maybe its just adjusted to high.in this case your pressure relief valve will open .If the pressure is fine and there is air coming out the relief valve then you have to replace it!to adjust your pressure turn the screw on your pressure switch clockwise to increase and counterclockwise to decrease .usually you have a 30 psi between cut-in and cut-off called the pressure differential.It can be adjusted on some pressure switch.be sure you put some teflon tape on the treads if you replace something to avoid air leaks.hopes this help!
I have a 2006. At the top of the head there is little hole about the size of a pencil and goes no where, but in that hole is a little hole about the size of a pin, that is where I am losing air. Is it supposed to be there?
I have the same compressor with the same problem. If the hissing is coming from inside the plastic case where the compressor motor is, then it is probably coming from the pressure relief "hole" in the top of the compressor head. This is a smooth pencil-point-shaped hole in the top center of the head that relieves the pressure inside the cylinder when the compressor is not running, which enables easier starts without overloading the motor. Before you panic, this is NOT a problem. That hole is SUPPOSED to be there, and is the source of the hissing you hear for a second or two each time the compressor motor shuts off when the compressor is operating normally.
The problem is the one-way check valve where the rubber hose from the compressor motor meets the tank (part number 8 on the parts diagram). If that one-way valve fails, pressurized air that is supposed to remain in the tank flows back up through the hose and exits the pressure relief hole in the compressor head (path of least resistance). The cure is to replace the one-way valve (less than $20 from most sources).
In the meantime, you can continue to use the compressor. The compressor fills the tank faster than the pressure relief in the head releases air. The downside is it will hiss constantly, it will bleed down when not being used, and the compressor will run much more often, which will reduce its service life.