I’ve got a pump running glycol from the chiller and it makes a weird buzzing noise. One pump does it and one doesn’t, so clearly something is wrong. I thought that there might be some air in the head, so I loosened the nut to vent it and the pump quieted right down - success! Unfortunately when I tightened the nut again the noise picked right back up.
Can anyone tell me what is going on and how to fix it?
Here is a pic of the head zoomed in for part numbers, the nut is on the left.
Totally uninformed and without specific knowledge but if bleeding air from the head made the noise stop but then it started again could there be a pin whole somewhere in the lines from the glycol storage unit that is adding air on that one pump?
I forgot to mention - when I loosened the nut and it was quiet, I could see a lot of air bubbles in the stream that was being returned to glycol reservoir. When I tightened the nut and the noise started, the air bubbles in the stream disappeared. :-\
Obviously the answer is to leave the nut loose. 
I know I whine when my nuts are tight.
Sorry.
Obviously 
But I am worried that if I leave it loose it will vibrate even looser, and that’s when the glycol starts shooting out all over the place. You don’t want to have to clean up a large glycol spill, it is a PITA and that stuff is expensive!
Duct tape. ;D
I think you might have a kink or blockage in your system. Because opening vent you relieved pressure making pump turn free. I would move and squeeze the lines and see if you hear a change in the pump.
Your pump does not look like a March pump, but I have heard that sometimes the thrust washer is left off of the impeller spindle allowing the impeller to rattle around a bit. Make sure all the pieces/parts are in place inside the pump head.
Can you describe the noise? A whine? Or a growl?
Contract Michael Winslow to do an impression!
Buzzing. Its weird.
Thanks, I’ll give that a try. It seems to flow pretty well though.
I suggest ear plugs or a sledge hammer. One or the other would work.
Sorry Tom…but I just couldn’t help myself.
On a serious note…have you tried contacting the manufacturer, this is assuming they are designed in an American speaking business. Noted: assembled in Mexico
Ehhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
says the pump after I move the hose all around trying to find a kink or blockage. 
Ear plugs - definitely. Sledge hammer . . . maybe!
Have you considered cavitation as a noise source? Make sure the inlet is free of kinks or obstructions. Can you mount the pump lower, so that there is more head on the inlet?
Does the motor have brushes? Or a place to put a drop of oil? Sometimes taking the brushes out and hitting them on sandpaper cleans the contact and helps. Is there a capacitor on the motor that could be going ( if so switch between motors and see if it still makes noise) Is the one making noise running hotter or if you can turn shaft harder. Good luck
I’ll check it out. It is definitely not working right (not chilling) despite the good flow of glycol through the system I saw last week. I’m going to need to take it apart again, and don’t have time today. I might not have time next week either, we start pouring in our second location next Thursday and there is a lot to do. Including replacing the ballast on a fluorescent light, which is somehow my job :
These are good ideas, but because the noise goes away when I loosen the nut on the pump head I figure it is something in between the inlet and outlet of the glycol system.
Is the noise coming from the motor or the pump? From what I can gather, the pump is a Procon Model# 111A100F11AA. It does not come with a motor. You have to attach one separately. Are you operating it above 150F? That’s it’s upper limit.
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