Quincy 325 Air Compressor Unloader Valve not working.....

[IQRaceworks]

I have a 5hp Quincy 325 air compressor on an 80gallon horizontal tank. I rebuilt it several years ago....and it's always worked great. Just recently the unloader system on it has stopped working.

The way it's supposed to work is that when you first turn on the air compressor there is a valve on the high pressure side of the compressor that is held open to unload the pressure until the oil pressure builds to a certain level, then the valve is closed, and the compressor starts building pressure.

For some reason, my compressor is acting like the valve is stuck shut...it never unloads, even when I first turn the compressor on and there is no/low oil pressure.

I've taken the cap off on the unloaded that's on top of the head, and everything seems to be moving freely...nothings stuck.

Can someone give me some ideas on what could be wrong with it?

Thanks!!

 

[redmondjp]

Have you checked the oil pressure? The unloader is oil-pressure-activated - if you don't have any oil pressure, the pump stays unloaded.

If you do have oil pressure, the next thing to check would be the hydraulic unloader valve to see that it is not stuck in one position.

Also, have you downloaded the "Quincy QR-25 Series Instruction Manual" from the Quincy website yet? It has a detailed explanation of how the unloader works and a troubleshooting section.

 

[IQRaceworks]

Have you checked the oil pressure? The unloader is oil-pressure-activated - if you don't have any oil pressure, the pump stays unloaded.

If you do have oil pressure, the next thing to check would be the hydraulic unloader valve to see that it is not stuck in one position.

Also, have you downloaded the "Quincy QR-25 Series Instruction Manual" from the Quincy website yet? It has a detailed explanation of how the unloader works and a troubleshooting section.

Yes, I have oil pressure....but not until about 30 seconds after the motor starts running. That's the time when it should be unloading....but it doesn't. It never unloaded at startup......and it used to.

No, I don't have the manual....I will have to hit the Quincy website and download it. Thanks!

 

[redmondjp]

30 seconds before oil pressure buildup is waaaaaayyyy too long - you need to look into that. It should be up to pressure in a few seconds - check youtube videos for 325s in action - some videos show the oil pressure gauge during startup.

 

[IQRaceworks]

I did a little more trouble shooting on the hydraulic unloading valve. It seems like the valve is clogged up or plugged....when I have pressure in the tank going to the valve, and no oil pressure.....the valve should be open, allowing air pressure to flow to the unloader tower....but when I take the fitting off on the exit side of the valve...nothing.

I took the valve off, and manually worked the valve in and out (open/closed)....but I never could get any compressed air to flow though it.

According to the manual and parts diagram, there are a few check balls, a plunger, and a spring in that unloader valve. I'm guessing that something could be stuck?

I guess I will have to pull it all apart and see what I can find.

 

[IQRaceworks]

Well, I found out what was going on. There is a small little brass screen, and some type of fiber filter pressed into the in and out port on the hydraulic unloader valve that mounts to the side of the compressor. The little fiber filters were so gummed up, hard, and full of junk....that they were not letting any air into, or out of the valve. After I cleaned the screens...and tossed the fiber filters.......the valve started working like it's supposed to.

It was an east fix!

 

[redmondjp]

Awesome! Thanks for posting an update with the resolution - the can be very helpful for future readers who may have the same problem.