Quincy 325 not building pressure

[lance8615]

Can anyone give advice on fixing my sick Quincy 325? I rebuilt it a few years ago and it has been working great. But lately the unloader function has become very slow...instead of a sudden rush of air it was just a very slow leak that took a while to unload to where the flywheel would turn freely. So I took off the hydraulic unloader, cleaned the little brass screens, put in new felts, and now the compressor won't build any pressure whatsoever! Any ideas on where to go from here? Any and all suggestions are much appreciated! Lance

 

[rustyjames]

I had a 325 that did the same thing occasionally. I would just tap on the valves with something metallic on top of the head and it would start pumping. I ran it for years like that. My guess is the valve(s) were sticking at times, typically when the weather was cooler.