Originally Posted by John_Kunkel
The unloader is usually operated via a centrifugal valve in the crankcase but I think what you're seeing is the compressor head over-pressure relief valve which opens at a much higher pressure than the tank relief valve. Is the escaping air a steady stream or does it pulse?


It is a steady stream. There is a small hole on the face of it where you see the black sticker but that is not where the air is coming out. It's coming out on the side or from the threads where it screws into the pipe.