Compressor Noise

[Logoman]

Quincy Compressor makes a knocking noise periodically. Someone suggested it may be the Pressure Relief Valve on top of Compressor. When I purchased the part from Quincy distributer they told me that if this did not fix it then it would be the Valve Plate needing to be replaced. Replaced the Valve Plate and it still makes the noise. Any ideas?
Thanks
Pete

[screenxpress]

Google search with "Quincy Compressor makes a knocking noise" brought this up:

https://www.quincycompressor.com/whats-wrong-with-my-air-compressor/#excessive-noise

[Logoman]

Thank You

[screenxpress]

I hope it points you to the fix.  GL

[Binkspot]

Is it a knocking or burst of air you are hearing. Assuming it's a 310 and knocking it could be one of the valve cartridges or the unloader piston. Sometimes the inlet valve will get stuck and could hit the piston. There is an o-ring on the unloader valve, when that goes bad you can hear it clicking along with excessive time to close.